Posts by louis

louis · Human missions

Hi GW -

Wasn't querying your calculations - just puzzled as I'd read the Musk (mis)quote. Thanks for the clarification.

I think they should sacrifice 2 or 3 Starships on the surface. to establish a base, and develop a small lander-ascent vehicle to create the link between the surface and lunar orbit, which I presume will cut down dramatically on the need for tanker loading.

I see the lunar base as mostly an opportunity for tourism with some associated science. It's not going to be an independent civilisation as the Mars community will ultimately become.

Ultimately, Space X might be better advised to create hydrogen engines for their lunar rockets. We know there is plenty of water on the moon but processing carbon could be a real problem from what I've read.

GW Johnson wrote:

"Wasn't Musk saying though that the Starship could get to the Moon and back on one tank from launch?"
No, he never said that.
Orbital mechanics says that an unrefueled Starship lunar landing mission has a total delta-vee in the 8-9 km/s range from Earth departure orbit, while the one-way voyage to Mars has a total delta-vee nearer 5-6 km/s from Earth departure orbit.
The rocket equation says the mass ratio for ~6 km/s is one whale of a lot easier to achieve than one for 8+ km/s. It ain't linear, it's exponential. That would be at engine Isp's in the vacuum Raptor range.
Musk said a Starship could get to the surface of the moon and back, unrefueled, from an Earth departure orbit (and he said it was elliptical, not circular). He didn't say exactly how, or with what payload. I found ways to make that Musk statement true, using the best numbers we have for the expected production designs.
I cannot be that far off from what Spacex themselves are calculating. Remember, I used to do this same sort of thing or a living, about a quarter century ago. I do really know how to figure this stuff.
Lunar payloads are smaller than Mars payloads, and the number of tankers is really high, unless you pay very careful attention to exactly how you go about executing the mission.
The only ways I could find to do this lunar landing mission at all, will penetrate quite deeply into the Van Allen radiation belts, before departure from an elongated elliptical departure orbit. Cargo MUST therefore be radiation-hard, and any crew or passengers WILL require a substantial and effective radiation shelter! There is NO way around that requirement!
But it can be done, and I found a way to do it with only one (!!!!) more tanker flight than is required to fully refill the mission Starship in low circular Earth orbit, not double or triple. I did that without any computer software or orbit or trajectory programs on any computers. I thought that accomplishment in itself was quite the remarkable finding!
BTW, that says NOTHING about tall skinny landing stability, or the bearing pressure on soft soils. Those, and many other fatal problems we have already begun to see in prototype test flights, remain to be solved, before any such missions will ever fly!
GW

louis · Human missions

Interesting stuff!

How difficult would it be to simply sacrifice a Starship on the lunar surface and use something similar to the Apollo lunar ascent vehicle to
rendezvous with a lunar orbit Starship? We know the LAM was used very successfully on - what? - 7 occasions. The designs are out there. Shouldn't be that difficult to put together.

Wasn't Musk saying though that the Starship could get to the Moon and back on one tank from launch?

GW Johnson wrote:

Following upon what I said in post 985 above, I have been working on the Spacex tanker issue. Specifically, the departure orbit requirements and approaches to refilling, for lunar landing missions. Those are considerably more demanding than one-way Mars missions, because there is no propellant manufacture on the moon.
I could not make lunar nearside landings feasible unless I used elongated elliptical departure orbits, with apogee altitudes well into the Van Allen radiation belts. I sort-of bounded the problem with 75 tons to the moon and 0 tons returned, from a 300 x 7000 km altitude departure ellipse, and 59 tons to the moon with 32 tons returned, from a 300 x 10,000 km altitude departure ellipse. The base of the Van Allen belts outside the South Atlantic Anomaly is considered to be about 1400 km altitude. Radiation exposure before lunar departure is a very serious issue for these kinds of missions.
I looked at dedicated tanker designs, and at using ordinary Starships as tankers by flying at zero payload to have excess propellant left over. They're not that different in capability, as it turns out. The ordinary Starships can deliver about 192 metric tons of usable propellant to low circular orbit, and the dedicated tanker with extra tankage volume about 230 tons. All that assumes these designs can be made to work right at only 120 tons inert vehicle mass.
Tanker capacity to the higher-energy elliptic departure orbits is around 5-10 times less. For refueling a max-payload Starship in low circular orbit, I found 6 dedicated tankers and 7 ordinary tankers, because the Starship arrives there dry of all propellant except an emergency landing reserve of 21 tons, out of a capacity of 1200 tons. The number of tankers needed to fly directly to the elliptic departure orbit and refuel the Starship there fell between 15 and 21 flights, depending upon which orbit, and which tanker version.
The next idea I pursued was to fly at only the lunar payload to low circular, and fully refill there. Then move to the departure orbit, and top-up from tankers sent straight there. Again, tanker capacity to the elliptical orbits was low, leading to around a dozen refueling flights. Or more.
The next idea was to refill both the mission Starship and one tanker in low circular, where tanker capacities are high. Then move the refilled Starship and that one refilled tanker to the elliptic departure orbit. There, the tanker tops-up the Starship, holding back only its landing reserve. I was afraid it might take two, but preliminary results seem to indicate I can get away with just one extra tanker that way. Which looks sort of like 7 dedicated tankers or 8 ordinary tankers to run one of these lunar missions.
There is very, very definitely a distinct advantage to maximizing the number of operations done in low orbit. The "tyranny of the rocket equation" has definitely struck again.
GW

louis · Science, Technology, and Astronomy

kbd

I think this article answers some of the points you make:

https://www.theguardian.com/world/2020/ … rst-flight

The real attraction for operators will be the lower running costs of electric aeroplanes - maybe 40-70% lower according to the article, which sounds about right to me.

Everything has to start somewhere - modern planes started with the Kitty Hawk. The 9-seater looks viable for short island hopper flights.

I don't think you understand the relative significance of EROI or how it relates to green energy.

Try this thought experiment. You are a clever engineer who creates a magnificent set of algorithms which allows solar powered robots to function in the asteroid belt, mining materials, refining raw materials, constructing factories and making things. These robots are so clever they can even build rockets. Now, you being so clever have built into these robots' algorithms that they will always want to serve you and bring you finished products at no charge. The robots built a nice rocket landing pad near your home and periodically bring you lovely products entirely free of any charge.

Now, it is clear these robots are using huge amounts of energy to operate in the asteroid belt and make the products they do. But it is equally clear from this experiment that they have no reason to levy any sort of charge, despite the prodigious amounts of energy being used.

What really creates the need for price is human labour input. It isn't the fact you use x KwHs in making a product that determines its price, it is that in order to use x KWhs, z number of people are employed in helping get that energy to a point where it can be used in the making of the product. This applies though only where people are free because free people will not work without reward. If we look at slave labour, again there is no need to generate price. On a Roman villa farm lots of activities would take place and products would be made - all involving slave labour - but at no cost to the slave and land owner. Same on slave plantations in the past in the Americas. Yes, the slave needs to be fed and otherwise minimally maintained, but that is like the energy used by the robots.

Your point about energy budgets for activities is of course a truism. If an activity is not generating energy, then it cannot continue indefinitely without additional energy inputs.

The error I think you fall into is assuming that EROI is the key factor to energy budgetting, It isn't. The key factor is relative ubiquity. The point about energy resources like wind, solar and geothermal is they are pretty much ubiquitous across the planet. To take solar, the energy from the sun transported to the planet is huge, enough in one hour to power humanity's needs for decades. More than that, it is readily available all around us, not concentrated in a few locations. So even if solar let's say had an EROI of only 5% of coal's EROI, if we have the right technology - meaning in effect the right price - we can easily build up a larger energy surplus from solar than from coal. So while it's true - in this case - that for every 1 energy unit put into coal I get 100 and I only get 5 from solar, solar is all around and easily available to use if you have the right technology whereas coal is unevenly distributed and its extraction involves mature technologies that are not going to deliver major cost reductions. With solar you have a scenario where you can just invest the 1/4 of your energy surplus back into solar and you can continue to grow your energy surplus at a prodigious rate. With coal, if you did that you would soon strip all the more easily accessible coal deposits. But with solar we can go on and on, and if we get the technology right we can exploit solar power beyond the narrow confines of Earth e.g. with solar power satellites.

kbd512 wrote:

Louis,
First, a quick correction. I keep calling the converted battery powered DHC-2s (Beavers) operated by Harbor Air in Canada, as part of a commercial / for-profit passenger ferrying service, DHC-3s (Otters / Sea Otters if they're float-equipped). That's wrong. The battery converted airframes are in fact DHC-2s, not DHC-3s. The DHC-2s are better known in aviation circles as Beavers, a truly superb Canadian designed / built STOL or "bush" cargo aircraft that has withstood the test of time, and is built like an anvil. Once upon a time, the US Army and USAF-sponsored Civil Air Patrol used a number of Beavers for a variety of missions. In total more than 1,600 DHC-2s have been built, and nearly all of them are or were used for commercial or military operations. Harbor Air operates a number of float-equipped Beavers and Sea Otters, with most DHC-2s powered by P&W R-985 "Wasp Junior" radials (AVGAS burning WWII-era utility aircraft engines made by the thousands) and all DHC-3s powered by P&WC PT-6A gas turbines (JET-A burners). A handful of the DHC-2s had their radials replaced with MagniX electric motors and Lithium-ion batteries for very short 15 minute hops across the bay that Harbor Air operates out of. That said, I could've sworn I saw photos of an all-electric DHC-3 in Harbor Air livery with a MagniX motor as a replacement for its PT-6A. Again, these were intended for very short haul flights between mainland Canada and small islands around the coastline.
I believe there are also some British designed / built Britten-Norman BN-2 Islanders that do 10 minute hops between islands that have also been or are being converted to use electric motors for very short haul flights between islands. Batteries do not pose any kind of engineering problem (read that as a weight penalty over a full gas or kerosene fuel tank) for 30 minutes hops, so they make a lot of sense for very short haul flights to reduce fuel and engine maintenance costs. However, if you need to fly for longer than 30 minutes, then you have a serious engineering problem if you intend to retrofit existing light aircraft with electric motors and batteries. The electric motors are not the problem, as they already greatly exceed the power-to-weight ratio achievable with gas turbine engines and are already 96% to 98% efficient at converting electrons into torque / power. Unfortunately, the low energy density of current batteries remains an intractable problem.
louis wrote:
Real price of oil hasn't changed much in 50 years.
https://www.macrotrends.net/1369/crude- … tory-chart
Real price of goods like fridges, cars, furniture, household goods and so on has declined. Real price of food has declined.
Manufacturing cost, which ultimately ties back to energy cost, sets the minimum cost for a good or service. The cost can never organically be lower than what it cost to produce something, in terms of energy / materials / labor. If you need to produce at least ten times what you did before, then total cost increases, even if per-unit price drops. The total cost still has to be paid by someone, so there's no point in arguing whether or not producing 10 tons of steel costs more than 1 ton of steel, because it clearly does and that's not changing to appease anyone's ideology. There can be artificially manufactured market scenarios that reduce cost below that point, but those events are always very short-lived and tend to destroy demand, which increases the price of the available supply. Absent government interference (and governments absolutely love to interfere in commerce), it's a mostly self-limiting and self-regulating system, that's dependent upon demand (someone actually wanting to buy something and being willing to pay for it) driving the cost and availability of the supply (determining prices through meeting consumer demand).
The price of oil has never been tied to what it cost to extract it from the ground. That has always been the case for as long as I've been alive, but what we're talking about is total cost and EROEI. Total cost and EROEI matters at a global scale, because money (the conversion of units of economic output, or the conversion of energy / capital / labor into something that a consumer needs or wants to purchase, into a tangible / fungible medium of exchange for the buying and selling of things of tangible value to consumers) can only be devoted to a limited set of priorities (the self-limiting and self-regulating feature of capitalism for consumers; if you spend all or most of your money on energy, then far less is available for education or construction). Anyway, as an example, the oil wells that were drilled in the 1950s in the Middle East allowed us to lap up entire lakes of crude oil after a comparatively minimal energy / capital / labor expenditure to get at it. That's no longer the case. It takes significantly more energy these days, for less return. There's no shortage at the present time, but the reserves won't last forever, because all resources on Earth are finite.
Refrigerators, motor vehicles, and household goods became faster to produce with less labor as more assembly line optimization and robotics were incorporated into manufacturing, which ensured that less touch labor, therefore manufacturing time, was necessary to assemble finished goods. We also moved the manufacturing of many of those goods to countries where wages are purposefully kept artificially low. The materials and manufacturing methods of the past were not nearly as optimized for mass-production. Basically, we kept finding faster and therefore cheaper ways to make things. I would like to point out that this doesn't change the energy requirement to produce 1 ton of concrete or metal raw material, nor the economy with which the required energy can be supplied to do that. We're not going to demand an order of magnitude greater materials input for the electricity generation industry, or any other industry for that matter, without sacrificing something elsewhere (increased emissions and cost of whatever the industry is supplying, such as electricity in this case, taking materials away from construction and transport and/or manufacturing of other goods).
Certificated aircraft, however, are still assembled by hand through complex multi-step processes, sometimes spanning months, that generally involve expensive specialized tooling and machining methods, from high-cost materials such as Aluminum and CFRP or GFRP, with high scrap rates due to the multi-curved component shapes being fabricated, typically using lots of touch labor and hand tools requiring considerable skill to use properly. There's really no such thing as semi-skilled labor in aircraft assembly. You don't need much formal education to do it, but lots of job experience is required to do it efficiently. Unfortunately, as the price increases there are fewer and fewer laborers devoted to building new airframes, so the marginal production costs continually increase while the supply of new airframes and engines decreases. That's why the price keeps going up!
Model Year 1958 Cessna 182 Sale Price: $14,350
Model Year 2019 Cessna 182 Sale Price: $515,000
The 2019 model year Cessna 182 has a Garmin touchscreen-enabled glass cockpit that cost approximately $30,000 to $50,000, dependent upon whether or not the aircraft is equipped for VFR or IFR flight (most are IFR-equipped). The older models had steam gauges for flight instruments, such as the 172 models I fly from the early 1980s, but even those setups will run north of $20K these days for an IFR equipped bird, and they're frequently less reliable than the solid state computers without routine maintenance. The empty airframe weight has increased by approximately 300 pounds from the first 1956 year model to the present day. The originals had a 230hp Continental IO-470 six cylinder engines equipped with carburetors, magnetos, and a vacuum pump for the flight instruments. The newer models have 235hp Lycoming IO-540 six cylinder engines equipped with the same or very similar carbs, mags, and vac pump. There's no electronic or computer-controlled anything on the engines from 1956, nor the ones from 2019. The components are made on CNC mills these days and take less time to produce, but the parts sheet hasn't changed in a long time. Both engines were certified in the 1950s and have remained in production ever since. I have steel cables that connect to / control the throttle, fuel mixture, and propeller pitch setting, and this is standard in virtually all piston-engined light aircraft. In nearly every other respect, apart from a handful of parts that were beefed up over the years to deal with various structural failures, the airframe is almost identical to the first models that rolled off the production line more than half a century ago. I believe you can take the wing off a 1956 model and attach it to a 2019 model, for example, not that FAA would allow you to do that. The fuel tanks on the newer model are larger (65 gallons for the earlier models vs 92 gallons for the newest models). As of about 10 years ago, they're now equipped with 26G impact protection seats and inertia reel harnesses to better protect the occupants in a crash. The 1958 model would burn ~11.9 gal/hr at economy cruise. The 2008 and onwards models equipped with the slightly larger displacement and more powerful engine, which are also about 300 pounds heavier on average, burn ~12.9 gal/hr at economy cruise. TBO and maintenance for the engines are also nearly identical.
The Continental IO-470 in the 1950s was a $3K to $5K engine, dependent upon options. That same engine today is a $70K to $80K engine. A certificated Lycoming IO-540 is about the same price, maybe a bit less. A non-certificated IO-540 (experimental aircraft engine, but made on the same production line, using the exact same tooling and quality control checks, by the exact same personnel, without the magic paperwork to keep the FAA happy- the "sprinkling with holy water" as we call it) is around $50K (and also makes 260hp vs 235hp). The cost increase is tied to increased labor and materials costs (that achieve the exact same end result using the exact same materials), paperwork tracking, and ultimately, the army of lawyers that the paperwork is being generated on behalf of (because it wasn't always this way).
You really think you're going to make a substantially heavier battery powered aircraft made from the same high-cost materials, with even more touch labor (composites fabrication labor ain't cheap), but somehow cost less money? I suppose anything's possible, but all previous industry experience says that won't happen. A battery equivalent aircraft will cost at least twice as much to purchase as a gas powered equivalent, and at least 8 times as much for equivalent range, because batteries, motors, and CFRP tooling and fabrication aren't cheap.
A battery powered Cessna 182 would cost $1M (with a lot less range), as compared to a $500K AVGAS powered variant. For you to spend as much on fuel as the increased purchase price of the aircraft, you'd have to fly for close to 11,000 hours. Most private pilots who are owner-operators fly their machines 100 to 200 hours per year, so at 150 hours per year, you'd have to fly for 72 years to recoup the cost difference between a gas and battery powered aircraft. I don't know many 88 year old pilots (guy or gal received their PPL at age 16 and then flew continuously for the next 3/4 of a century). Even if we allocated $40K for 4 engine overhauls for the Cessna 182, every 2,500 hours, we're still talking about multiple decades of continuous use before the battery powered version actually "costs less" to own / operate.
louis wrote:
I really don't think there's any evidence for material shortages pushing real price increases. There were commodity price increases around 2008 but that reflected really a credit boom that had got out of control, followed by a credit crunch.You can't expand things that require 30 years investment off the back of a credit boom.
I really don't think Calliban said there was. Both of us asserted that there would be at least an order of magnitude more material consumption associated with wind and solar, as compared to nuclear. This is pretty hard to argue since the wind and solar manufacturers frequently make it a point to brag about how much steel / Aluminum / Copper / concrete it took to make their products. We also know how much concrete and steel went into nuclear reactors that we've already built. Unless the materials suddenly cost ten times less, then someone, somewhere, has to pay for the increased materials consumption. That person is the rate payer in all cases. That's why electricity rates in Germany are 3X greater than in America, on average. More consumption of materials to provide equivalent energy always costs more money, with or without materials shortages.
I asserted that there would be Silver shortages if we tried to make every on-panel PV interconnect using Silver. All of the panels on my roof use Silver, for example. Commercial panels use Silver. I've explained why they use Silver instead of Copper at least a half dozen times now, so I won't repeat it again. Silver recycling will be mandatory for there to be a new generation of panels in 25 years time, assuming we start adopting current PV technology on a global scale. I presume that we will make what we actually know how to make, and this is what we know how to make. We can presently make macro-scale CNT wiring as conductive as Copper with appropriate doping, but not Silver, apparently. This was a bit of a bummer for me as well.
I also asserted that there's not enough Lithium in known reserves to give everyone on the planet an electric car with a 200kWh Lithium-ion battery pack, much less provide grid-scale storage. If someone can improve the energy density by an order of magnitude, then at least we can give everyone a car, but we still can't do grid-scale storage, beyond a handful of non-repeatable publicity stunts.
This is just simple math that anyone can do with a handheld calculator or pencil and paper, and a computer to "Google" the known reserve figures, how much Lithium is in a battery, current consumption rates, projected consumption rates, recycling rates (essentially zero), etc.
There's no shortage of steel and probably never will be, but that wasn't the point. The point is that at least an order of magnitude more steel / concrete / Aluminum would have to be devoted to wind and solar farms than with nuclear, and to re-power the entire world in 20 years, it's a non-trivial increase in the quantity of metals and concrete that we're talking about, meaning it will affect the ability of other industries to consume the materials for other useful purposes such as construction and transportation, along with emissions and the environment.
louis wrote:
I've been through a few countries' graphs and there seems no increase in commodity prices in the last 40 years. Take China for instance:
https://data.imf.org/?sk=2CDDCCB8-0B59- … 210D5605D2
Green energy for me is total sanity, not madness. How it's been implemented is another matter. I see it more as a public good like building freeways, which in the USA and UK were provided free to people, or like water in the Roman Empire which was provided free to people.
Here in America, all freeways are constructed and maintained using state and federal tax money or private capital, as are most water and electric utilities. When roads are funded by the tax payers, states and the people they hire can take years or even decades to build new roadways. When roads are built using private capital, strict timelines are adhered to and it's rare for them to be more than a month behind schedule, with most delays being caused by weather / manufacturing of materials / transport issues, rather than caused by politicians or unions collecting paychecks while thumbing their noses at the tax payers who are paying them. In any event, there's nothing "free" about any of the infrastructure we've built and there never has been.
The "madness" that I see in "green energy" is building something that lasts for 10 to 20 years at most, at considerable cost (energy / capital / labor) for the energy it returns, that will never be an acceptable substitute for a real electric generating station that predictably produces energy, 24/7/365, and then having to rebuild a substantial portion of it all over again, into perpetuity. I'm not opposed to building solar thermal power plants because those at least have the possibility of being 24/7 power plants with sufficient molten salt storage. That form of energy storage is integrated into the plant design rather than being a separate add-on, so it's much cheaper than batteries since both salt and steel are plentiful and inexpensive (so there's at least the possibility of global scalability and continued use into perpetuity), and the salt isn't subject to serious degradation over time. The steel can corrode, but we can recycle all types of steel and produce new steel that's every bit as good as or even better than the virgin steel, and we do that on the regular at a global scale. On that note, the mirrors used aren't really subject to meaningful degradation over time, either.
I've spoken with a PhD in chemistry at some length about Lithium-ion battery technology. She told me that the firm she works for has literally gone through more than a million different chemical compounds in an attempt to arrest the growth of dendrites that ultimately render the battery unusable, but all of them had other deleterious effects on other aspects of the battery's performance (weight or storage capacity or achievable charge / discharge rates), which is why none of them were ultimately pursued further. Everything is a compromise. I presume other researchers have also tried every little trick that they can conceive of, but we're basically stuck with minor variations on current technologies, with little meaningful improvement. She said that they were basically refining the fabrication methods of current technologies to the nth degree, which is the only reason why cell energy density continues to improve, but that there were limits to what was practically achievable by doing what they were doing. At this point, she said they were putting more effort into other cell chemistries besides Lithium-ion, since most real progress to date has been manufacturing process control improvements (still very important, but not a game changer). Unless they can engineer solid state batteries to the point of being production-ready, or make use of nano-materials to drastically increase the surface area of the active materials while suppressing dendrite growth, there won't be any remarkable improvements to the energy density of existing jelly roll designs. As such, the solution to all energy storage problems is highly unlikely to be a battery, and grid scale storage will remain absurdly impractical, if not utterly impossible, using existing technology. The more we understand about the basic physics of how batteries work, the less likely that appears. Other researchers have stated as much in presentations they've given. They'll continue to pursue anything that looks promising, but very little of what "looks promising" in a lab setting will ultimately find its way into production cells, because nearly all of what they find is ultimately a dead end. Coming up with a practical light bulb filament was child's play, by way of comparison. They're also using AI to try to predict active material interactions / behavior, but even the AI has yet to come up with something usable, so it's an exquisitely tough nut to crack.
Let's say a company like QuantumScape truly can "deliver the goods" and Volkswagen can readily produce a 0.5kWh/kg / 1kWh/L solid state Lithium-ion battery that can be manufactured at some reasonable cost. It still only lasts for 1,000 cycles at 80% DoD, before retained capacity falls to 80% of its initial capacity. It can charge and discharge much faster, which is very helpful, but what have we really accomplished? Kerosene / Diesel / Gasoline are still around 13kWh/kg and Methane is more than 15kWh/kg. Power plants and large aircraft engines can extract 50% to 65% of a hydrocarbon fuel's energy content, so we're still more than half an order of magnitude away from the energy density of those fuels. No aircraft in the world can carry 6 times as much "fuel" weight, in the form of batteries, and still perform as it did using hydrocarbon fuels. We could have electric trucks that still retain 3/4ths of their payload capacity.
Photovoltaics are semi-conductors with insanely high scrap rates. 1kg of usable semi-conductor material has around 100,000kg of scrap or kerf associated with it. Granted, they're very lightweight, but after you scale up to a global level, that kerf rate starts to matter a lot. That level of inefficiency would be insurmountable for nearly any other industry. Modern batteries are very complex electro-chemical devices that degrade substantially over time, despite the high energy / labor / capital costs to build them, and use a slew of materials that are not so plentiful or cheap. Making a battery is relatively easy, and many of us did it in grade school as kids. Making an energy-dense battery with consistent performance is absurdly difficult, to the point that we're now expending non-trivial amounts of super computer resources on computational electro-chemistry to try to tell us how to improve the things beyond where we're already at. Once they're sufficiently degraded, we don't have a good way, or any way at all in some cases, to recycle them to produce new photovoltaics and batteries. The only types of batteries with good recycling rates are Lead-acid batteries, but the latest incarnations of those batteries also make recycling or refurbishment far more difficult.
louis wrote:
We've recently just wasted an utterly incredible £400 billion on a range of ineffective responses to the Covid pandemic in the UK. If we had invested just half of that over the next 20 years in green energy, we could slash people's energy bills, improve air quality and secure our nation's energy independence. The problem with green energy is it requires substantial upfront capital investment. So far the public have had to bear that upfront cost.
Yeah, so now that £400B isn't available for other purposes, because the broken window logical fallacy is exactly what the name implies- a logical fallacy. You can't save money by spending money. That's not how "saving money" actually works, never has, and never will. Does any university on the planet still teach Economics 101 or Introduction to Business? You can claim that you're "investing in the future" (and we can debate the end results of investing in X / Y / Z technology) by spending more money, but you can NEVER claim that you're "saving money", because the dictionary definition of what you're doing is... SPENDING MORE MONEY! I wonder if Calliban and I were the only kids in school who weren't "out sick" the day they taught the fundamentals of economics in high school and college.
louis wrote:
Canada has big distances and not many people. In Europe about 300 million people are within 2 hours' flying time of each other. Obviously electric planes are not going to supplant conventional planes over night but I can see them getting a cost advantage over big jets for city to city passenger flights in Europe. Viable commercial flights might not be that far away:
Good for Europeans. Now you "just" (that filthy four-letter word keeps popping up all over the place) need a battery that weighs more than the max takeoff weight of a Cessna 182 (3,100 pounds) to transport yourself there using current battery technology. The fuel may be cheap, but an airframe that's double the weight of the 182 won't be. How many of you are willing to part with a million dollars to purchase a battery powered aircraft with Cessna 182 speed and less than 1/3rd of the range of the 182, when you could buy a small turboprop with the kind of money involved, and fly more than twice as fast? I could simply mix in the words "battery" and "electric" into any particular application and then our "green energy" people suddenly become incapable of basic math when it comes to estimating performance achieved per dollar spent.
Americans can buy American-made electric light aircraft at this very moment:
Bye Aerospace eFlyer 2 electric trainer - $349,000 for the base model
Bye Aerospace eFlyer 4 electric trainer - $449,000 for the base model
Europeans can buy Slovenian-made electric light aircraft at this very moment:
Pipistrel Alpha Electro electric trainer - $142,000 for the base model; $7,400 to $15,800 for the charging station
Yet... Very few people are actually doing that, because none of those birds can stay in the air for 2 hours at any significant speed, much less 4 to 8 hours. I can go on Trade-a-Plane at this very moment, purchase a $25K Cessna 172, throw about another $20K worth of repair work at it, and then I can pay for AVGAS or MOGAS at any airport in America and fly for 4 hours straight to wherever I want to fly to.
louis wrote:
"Engineers are currently trying to build a 180-seat fully electric jet that can fly for around 500km. The budget airline EasyJet has partnered with the aviation start-up Wright Electric to design and develop such a prototype plane that, if successful, could enter commercial service as early as 2030. Its travel routes would be limited – Paris to London for instance, not much further – but narrow-body aircraft that fly short-haul routes of 1,500km or less make up around a third of aviation emissions, according to management consultants Roland Berger."
https://www.bbc.com/future/article/2020 … ver-to-fly
Given the fuel costs are so much lower, and I believe maintenance costs will also be a lot lower, then I think electrical airplanes could soon dominate the short haul flight market in Europe and N America.
A fully-electric Boeing 737 or Airbus A320 like-kind replacement REQUIRES* a battery energy density of roughly 2,600Wh/kg (presuming the batteries weigh the same as the JET-A fuel that they completely replace).
* Definition of "REQUIRES" (in this context) - an utterly non-negotiable pre-condition to achieve the same range as a kerosene powered airliner (and no, increasing weight is NOT an option, because that requires more power to lift more weight, which creates more induced drag, which in turn requires more engine power to overcome the additional drag, and even if you fly a bit slower, that means you're in the air for a longer period of time, which also means you need more energy storage)
The "engineering solution" to the problem is to increase battery energy density by a little more than a half order of magnitude over what this new solid state Lithium-ion battery can achieve, presuming it makes its way to production, which has yet to happen.
Those strange-looking little "pods" on the tips of the empennage of the Wright Electric / EasyJet "all-electric aircraft" artist's rendering are, according to Wright Electric, turboshaft engines (a type of gas turbine engine) that spin electric generators (VFGs, actually), all examples of which are presently powered by kerosene. An all-electric jet is merely their goal, and Wright Electric stated as much.

louis · Science, Technology, and Astronomy

Yes I did look at the chart. We're talking about real, indexed prices here.

The price range in the 1970s was $21.47 to $107.42 and in the 2010s it was $37.43 to $133.18 and while I am not going to waste time analysing it further to get averages you can see with your own eyes that most of the time in both decades it was bobbing up and down in the middle of those price ranges, so with much the same sort of prices. There is no evidence of material shortage producing large price increases. None at all.

Between 1994 and 2019 oil production increased by what looks like about 20%. It did not decline.

https://www.bp.com/content/dam/bp/busin … tsr-bp.svg

So again, nothing to support your theory.

While you might be right that it now costs more energy to get oil out of the ground - it certainly costs far less to get it from A to B thanks to huge improvements in shipping and transportation generally and I am sure there have been energy efficiencies even in drilling.

As already explained you have to examine how much material is being used by an energy system in a lifetime. It would be a complex calculation but you cannot arbitrarily cut off the analysis at the initial investment stage. If the average nuclear power station is using a couple of tons of stuff a day then that has to go into the tonnage account - and over 25 years it is over 18000 tons. You don't like the idea of taking account of the tarmac in the staff car park but if that tarmac is being used by the nuclear power industry it is not available to anyone else for any other purpose.

Calliban wrote:

Louis, did you look at the chart you posted?
The price of oil has changed a very great deal over the past fifty years. In fact, there is a definite increase in real prices since the 1970s and also, greater volatility. It is the second factor that is in many ways more telling. The reason the price goes up and down a lot is due to boom-bust cycles, leading to changes in oil affordability. This is a tug of war between two opposing factors. Production costs have increased in the non-OPEC world, which has gradually pushed the profitable oil price upwards. Populatiin has grown explosively in the Arab world, meaning that OPEC nations need a higher price to fund public services. Rising oil prices tend to stoke inflation, because oil is used in the manufacture of many things and the transport of literally everything. Central banks raise interest rates to bolster the value of their currencies against inflation. This results in strengthening of the currency, but also debt default, expensive money and puts the brakes on the monetary conditions needed for economic growth. Wide scale defaults, unemployment and defered investments, then reduces the price that consumers can afford to pay, leading to lower oil prices. This is exactly what happened between 2003-2009 and it ended in the Great Recession. Notice also an oil price spike around 1990. Not long before the recession of the early 90s that forced Thatcher out of power. A coincidence? The sort of boom and bust conditions since the 1980s are exactly what one would expect from an economy that is approaching production constraints of a resource that is not readily substitutable.
I would argue also, that prices are not necessarily a good indication of material abundance. They are an equilibrium between production costs and what the consumer can afford to pay. If net energy available to civilisation is declining due to declining EROI of the dominant energy sources, then many commodity prices may go down. This does not indicate increasing abundance. It is destruction of demand. This explains why oil demand in OECD countries has fallen since 2009. It wasn't because we suddenly invented something clever that allowed us to do more with less. It was because people started getting poorer. The disposable income of most consumers is declining and wealth distribution is becoming increasingly unequal. Exactly what would be expected in a thermodynamic energy collapse of an industrial economy.
https://economicsfromthetopdown.com/202 … ffordable/
The problem we are facing is that what we call 'the economy' is a collection of processes that follow the laws of thermodynamics. As such, the economy produces wealth by using high grade energy to carry out work (in the physics sense) on matter. Waste products are produced in the form of heat and amorphous materials, that would take more energy to recycle. We need to invest a greater proportion of our net energy, every year, just to maintain our energy production as depletion reduces production in existing wells. Until about 2000, the western world was able to stay ahead of depletion, by taking advantage of increasing geographical reach (Middle East, North Sea, Alaska, Africa, Canada, etc) and by using new technology to access new resources (i.e. deep drilling and offshore). We were however, living on borrowed time, as conventional oil discoveries peaked in the 1960s. Since discovery must precede production, it was only a matter of time before oil faced production constraints and conventional oil production ( i.e the affordable stuff) peaked around 2005. The Great Recession followed not long after, as rising interest rates, designed to quash oil-induced inflation, pushed marginal debtors to bankruptcy.
https://www.bloomberg.com/news/videos/2 … since-1947
By the turn of the century, there were few regions left on Earth to explore, at least for conventional oil and gas. At this point, new technology, such as horizontal drilling, hydraulic fracturing, CO2 and salt water injection, could only mitigate the effects of depletion. The US was able to dramatically increase oil production by using new horizontal drilling technology to develop tight oil contained within sedimentary shale strata. What technology could not and can never do, is change the nature of the resource. It took zero effective interest rates and huge sums of money to make the tight oil boom possible. Even with rates close to zero, it was unprofitable for most companies involved and production has scaled back. Would any company seriously invest in a resource that required such enormous rates of drilling, if abundant, low cost conventional oil were available?
Since 2008, monetary policy has taken some truly unprecedented turns. Interest rates have been cut to effective zero now for over 10 years in OECD countries. Bond yields are extremely low and quantitative easing has been used to inflate the quantity of currency to fund spending, to the tune of trillions. This sort of behaviour would have been unthinkable to most economists in the year 2000. These are clearly quite desperate attempts by central banks to foster the new growth needed to pay off existing debts. What sort of an economy needs to price credit beneath inflation and print money out of nowhere to cover persistent budget deficits? An economy that can no longer grow in real terms without such assistance. An economy in which marginal energy costs have risen to the point where further economic growth is impossible. An economy in which so much energy budget is consumed in powering present day consumption, that little remains for reinvestment.
What is interesting about this situation, is that the price of commodities may not rise, even as they grow more scarce. If energy supply constraints are resulting in consumers becoming poorer, then commodities may experience price declines as fewer and fewer customers are able to afford them. Widespread deflation is possible at this point.
Why is it important that wind and solar power use 1-2 orders of magnitude more metals and concrete than nuclear power plants of the same energy output? Because it takes energy to get those resources out of the ground and process them into something useful. That energy requirement incidentally, is dominated by fossil fuels because mining and transport require liquid fuels and steel and concrete manufacture need high temperatures and reducing agents. We generally exploit the most profitable resources first. That means the most concentrated ores; the ones in easy to access areas, with low transportation costs and those available with open cast mining. Only a limited proportion of materials invested in making anything are recyclable at an affordable cost. In summary, it is possible to run out of metals and other raw materials, even though none of the atoms have left the Earth surface. The entropy of those materials increases, meaning that the energy cost of producing them increases with time. This happens at the same time as the abundance of surplus energy is decreasing. Hence, materials costs increase, even as their affordability declines, due to declining surplus energy. And because consumers are getting poorer and can afford less, prices may actually decline. Note that the total number of atoms of any element on the planet stays the same. And gross energy production may even increase. We still end up at the point where civilisation collapses, because surplus wealth after the essentials of life are paid for, falls below what is needed to maintain infrastructure and maintain materials production. This describes the thermodynamic energy collapse of a complex society. We are quite a long way down that road already.

louis · Human missions

Felix produces high quality videos on Starship development. His latest is no exception.

I didn't realise though that Space X have a target date for orbital flight of 1 July. Anyone else know about that?

https://www.youtube.com/watch?v=irw9t_R7-8M

louis · Human missions

Yes, I guess a belly lander would make a lot of sense for a rough field landing. But not so much for take-off. Must surely increase the risk of damage to the rocket?

Quaoar wrote:

louis wrote:
I expect the TAF factor cuts both ways - it allows them to adopt fresh approaches to long standing issues that sometimes work better (and a lot cheaper). That's the sort of approach that allowed Tesla to get a lead in EVs - they didn't just bolt on batteries to an existing vehicle model.
On the subject of legs, I was wondering about a supplementary stability set up. So you keep the stubby legs but at the bottom of the rocket you have three or maybe five extendors that follow the rounded contours of the rocket (so not like the Falcon 9 with its fold down legs going up the rocket body). As the rocket lands, these extendors, connected to the rocket body by hinges move out from the rocket body and stabilise the rocket on landing. With a circumference of over 28 metres to play with 5 of these curved legs could each be 5 metres in length. But that might be too much. I'm thinking (intuitively and probably wrongly!) perhaps 3 metres would place less strain on the hinge. Just another thought as well - if they were on springs and held back mechanically, leg deployment might used far less energy - just a case of moving 5 bolts out of place. There might need to be mechanism to lower the legs slightly so they make good contact with the ground.
You might be able to fire all the bolts with pyrotechnics which I understand have proven to be a very reliable technology in rocketry over the years, to effect mechanical movements.
Probably, now it's too late to change the design, but wouldn't it better to build a belly-lander with main rockets on the tail, landing/take
-off rockets on the belly, plus four landing legs?
A belly-lander is much more stable and would be a more practical surface habitat for the astronauts, who don't need to take a complex elevator every time they return from an exploration, but a simple ramp with steps.

louis · Human missions

I expect the TAF factor cuts both ways - it allows them to adopt fresh approaches to long standing issues that sometimes work better (and a lot cheaper). That's the sort of approach that allowed Tesla to get a lead in EVs - they didn't just bolt on batteries to an existing vehicle model.

On the subject of legs, I was wondering about a supplementary stability set up. So you keep the stubby legs but at the bottom of the rocket you have three or maybe five extendors that follow the rounded contours of the rocket (so not like the Falcon 9 with its fold down legs going up the rocket body). As the rocket lands, these extendors, connected to the rocket body by hinges move out from the rocket body and stabilise the rocket on landing. With a circumference of over 28 metres to play with 5 of these curved legs could each be 5 metres in length. But that might be too much. I'm thinking (intuitively and probably wrongly!) perhaps 3 metres would place less strain on the hinge. Just another thought as well - if they were on springs and held back mechanically, leg deployment might used far less energy - just a case of moving 5 bolts out of place. There might need to be mechanism to lower the legs slightly so they make good contact with the ground.

You might be able to fire all the bolts with pyrotechnics which I understand have proven to be a very reliable technology in rocketry over the years, to effect mechanical movements.

GW Johnson wrote:

Quaoar:
The answer to your question is "they themselves have not done it before". Most organizations refuse to learn from prior experiences of other organizations, especially those outside their very restricted experience base and engineering discipline. It is often a fatal mistake.
Spacex got caught by that lack once before, when they first started flying Falcon-1. It nearly bankrupted them before they got it right. What they knew well was liquid rocket engines, that being the Merlin kerolox engine still used in Falcon-9 and Falcon-Heavy. What they did NOT know (that they didn't know) was anything about the flying of staged supersonic vehicles.
That lack caused 3 collisional failures due to the drafting effect, which is quite strong in supersonic flight, despite the thin air at staging altitudes. They got it right on the 4th flight, which averted bankruptcy. And they have gotten that part right ever since. But that is NOT the only thing that they know little-to-nothing about.
What they don't yet know that they don't know is what it takes to be stable against easy tip-over from statics 101, and also what it takes for soft dirt to support a heavy object, which actually comes from civil engineering foundation design, nothing to do with aerospace. The reason they don't yet know about these things is that they have never landed anything, on anything but a flat reinforced concrete pad or a flat steel deck.
It is precisely a "technical arrogance factor" that prevents them from learning the already-known lessons about static stability and soil bearing strength from the experiences of others. They are not alone in that technical arrogance factor, which is fundamentally also a technical ignorance factor. Most big organizations suffer from it. (Including outfits like NASA that ought to know better.)
GW

louis · Science, Technology, and Astronomy

Real price of oil hasn't changed much in 50 years.

https://www.macrotrends.net/1369/crude- … tory-chart

Real price of goods like fridges, cars, furniture, household goods and so on has declined. Real price of food has declined.

I really don't think there's any evidence for material shortages pushing real price increases. There were commodity price increases around 2008 but that reflected really a credit boom that had got out of control, followed by a credit crunch.You can't expand things that require 30 years investment off the back of a credit boom.

I've been through a few countries' graphs and there seems no increase in commodity prices in the last 40 years. Take China for instance:

https://data.imf.org/?sk=2CDDCCB8-0B59- … 210D5605D2

Green energy for me is total sanity, not madness. How it's been implemented is another matter. I see it more as a public good like building freeways, which in the USA and UK were provided free to people, or like water in the Roman Empire which was provided free to people.

We've recently just wasted an utterly incredible £400 billion on a range of ineffective responses to the Covid pandemic in the UK. If we had invested just half of that over the next 20 years in green energy, we could slash people's energy bills, improve air quality and secure our nation's energy independence. The problem with green energy is it requires substantial upfront capital investment. So far the public have had to bear that upfront cost.

Canada has big distances and not many people. In Europe about 300 million people are within 2 hours' flying time of each other. Obviously electric planes are not going to supplant conventional planes over night but I can see them getting a cost advantage over big jets for city to city passenger flights in Europe. Viable commercial flights might not be that far away:

"Engineers are currently trying to build a 180-seat fully electric jet that can fly for around 500km. The budget airline EasyJet has partnered with the aviation start-up Wright Electric to design and develop such a prototype plane that, if successful, could enter commercial service as early as 2030. Its travel routes would be limited – Paris to London for instance, not much further – but narrow-body aircraft that fly short-haul routes of 1,500km or less make up around a third of aviation emissions, according to management consultants Roland Berger."

https://www.bbc.com/future/article/2020 … ver-to-fly

Given the fuel costs are so much lower, and I believe maintenance costs will also be a lot lower, then I think electrical airplanes could soon dominate the short haul flight market in Europe and N America.

kbd512 wrote:

Louis,
You didn't read what Calliban actually wrote, else you'd know he never claimed that we were running out of materials. He stated that the cost associated with exploiting the cheapest forms of energy, fossil fuel energy, is increasing, because all of the cheapest-to-exploit reserves have already been exploited, so total output units of energy, per unit input of energy, is declining. That means everything else that depends upon cheap energy, which quite literally is "everything else", will increase. We deliberately haven't provided a like-kind replacement, because we've been entertaining this "green energy" madness that costs a lot of green and produces less energy, relative to the units of input energy.
We already have electric commercial aircraft operating in Canada, on the regular. They're converted DHC-3s (previously powered by PT-6A turboprops) that can make 15 minute hops across the bay on battery power before eating into reserve power. If their battery energy density was doubled, then they could fly for 30 minutes before eating into reserve power. Most places that I and most other people fly to, are located 2+ hours away by air, and typically 3 or 4 hours away. That means the battery energy density needs to improve by a factor of 8 (8 times more energy dense than they are today, in order to provide a similar type of service, at any weight associated with commercial passenger service. Since the aircraft never gets any lighter as they "burn through" their electron-based "fuel", it's probably more like 10 times more energy dense. No such battery technology animal exists today, not even in a lab. If it did, then our "green energy" crowd would be shouting about it from the rooftops.
Commercial aircraft are priced based upon weight class, because it takes a certain weight of materials, which require energy input, in order to fly. The aircraft of the 1950s cost a lot less money, because energy was plentiful and therefore materials were cheap. Such is no longer the case, and the embodied energy in the materials used today have drastically increased, even though empty weight has not.
If a battery powered aircraft is 8 times heavier than a kerosene powered aircraft, then it will cost 8 times as much to build, require more power to accelerate it down the runway to rotation speed, it likely needs more power in level flight, and better aerodynamics, since it WILL generate more induced drag to produce the lift required to keep it airborne at commercial airliner speeds.
There are some clever aerodynamics tricks to minimize induced drag (the most important of them is reducing weight, which affects everything else), but the Rolls Royce battery powered abortion (based upon the Nemesis NXT racer design created by American pilot Jon Sharp) has a top speed of around 340mph, despite having 1,000hp on tap, as compared to the 350hp Lycoming TIO-540 turbocharged six-banger that pushed Jon's Nemesis airframe to over 415mph in a Reno air race using far less horsepower than the battery powered RR variant. The battery powered variant can cover 210 miles using 3 nose-mounted 72kWh battery packs that weigh 375 pounds more than the maximum takeoff weight of Jon's original Nemesis NXT design, which cruised at 325mph and could cover more than 1,400 miles by burning 20 gallons of AVGAS per hour. RR used Tesla's batteries and managed to cut the total pack weight in half, achieving a whopping 160Wh/kg energy density at the pack level, when compared to the packs in Tesla's cars, by removing most of the pack safety features and packaging, and using an improved air-to-liquid cooling system to contend with the aircraft's 10C discharge rate.
Both aircraft are single-seat designs, so the single-seat battery powered nemesis needs a 216kWh pack to take a single pilot 210 miles at regional turboprop airliner speeds. To cover the 1,400 miles that the AVGAS powered variant could, the battery pack alone would weigh at least 20,825 pounds. The max takeoff weight of what we consider to be a "light aircraft" here in the states is 12,500 pounds or less. Anything heavier requires a commercial license to fly. Wouldn't you know it, the RR battery is almost exactly 8 times heavier than the 2,600 pound MTOW of the original Nemesis NXT racer for equivalent range. For perspective the BAE Jetstream 41 has a maximum zero-fuel empty weight of 21,400 pounds, so a battery that provides equivalent range / speed as the original Nemesis, still occupied by a single pilot and no one else, is nearly as heavy as the max zero-fuel weight of a 29 seat twin-turboprop regional airliner that has 3,300hp on tap.
Are you starting to "get the picture" regarding how laughably absurd and impractical any type of useful electric aircraft is, if it requires any range or payload to speak of? The battery is minimally 8 times heavier than the Nemesis airframe for equivalent range. No matter how light the airframe portion of the aircraft becomes, IT STILL DOESN'T WORK! If dimensions and materials cost stayed the same, which physics disallows for numerous reasons, do you imagine that Nemesis would ever have the same flying qualities if the battery alone weighed as much as a Jetstream 41, rather than a few hundred pound more than the original Nemesis at MTOW? There's just enough room in the nose of that RR abortion for 3 packs. You'd need to add another 21 72kWh packs to provide equivalent range (even more than that, obviously, since an actual airframe that could takeoff would have far more drag from a much bigger wing, require 3 times as much power, etc), but there's no place to put that stuff in the Nemesis NXT.
Anyway, that's why a single-seat solar / battery powered aircraft cost $70M to construct, is as large as an Airbus A380, and flies at the same speeds as a Piper Cub (a STOL airframe that trundles along at highway speeds) - you know, for those times you want to take a trip "across the pond" in about 50 hours. The dues to the piper, aka Physics 101, will ALWAYS be paid.

louis · Human missions

Latest video from Felix at WAI incorporating some nice aerial shots of the developing Boca Chica site.

https://www.youtube.com/watch?v=urDwwEZufiY

louis · Science, Technology, and Astronomy

Seems a bit silly to say we are running out of materials - how often have we heard that in the past...oil being the classic example. There's plenty to be mined from the ocean bed as well.

Elon Musk - who has a pretty good record on predictions, has predicted that commercial electric planes will be viable by 2023/24 thanks to advances in battery technology. I think such planes will be much cheaper to build and maintain. If I am right, that will add to the economic case.

https://www.independent.co.uk/life-styl … 91066.html

Renewal energy can support energy equipment manufacture and mining etc.

Calliban wrote:

louis wrote:
Well I am not particularly focussed on carbon emissions - more on sustainable green energy production of electricity as part of a wider green energy economy. I think a green energy economy will be a step forward in human development allowing energy independence for countries and even households, reducing environmental impacts across the globe and providing cleaner air in cities.
There is no such thing as sustainable green energy production. The renewable energy sources that you obsess over are about the least sustainable way of generating power that there is. I keep trying to explain this, pointing out how much embodied energy and materials wind turbines and solar panels need, at a time when raw materials are approaching production peaks. But it's like talking to a brick wall. You don't listen. This sort of ideological nonsense is exactly why we are never likely to get to Mars. We are now facing a sustained economic contraction due to depletion of high grade fossil fuels. Green energy makes this problem worse because it consumes a lot of fossil fuels and does not produce reliable electricity as an end product. It is a costly boondoggle. And it's advocates are blocking development of the real high power density energy sources that could replace fossil fuels. By pushing this you are actually damaging our chances of ever reaching Mars.
louis wrote:
I think wind power has some inbuilt technological requirements which will mean the cost reductions begin to level off. However, I don't think we are close to the bottom of the technological price reduction curve with solar. PV film printing, robot installation and maintenance and less costly materials are all going to continue driving down the cost, together with improvements in capacity output. We really don't know where this technology will lead. With solar power aeroplanes and ultralightweight PV film, we may find ways of exploiting the perfect solar conditions above the cloud layer. Who really knows? The point is we are nowhere near the end of the solar power technology route.
Solar powered aeroplanes are toys for bored scientists. They have few real world applications. The energy flux on their wing area is no more than a few tens of kW. That means no practical payload capability, as what little lift they provide is consumed by the air frame. If you did the arithmetic you would know that. You cannot replace the hundreds of MW of power provided by a 747s engines using solar panels mounted on an aeroplanes wings. It doesn't matter whether they are thin film or not. It is a power density problem.
Synthetic liquid fuels to replace fossil fuels have the advantage of being storable for long periods in steel tanks and useful in portable applications. But there are inefficiencies involved in their production. These are rooted in thermodynamics. To produce synthetic fuels cheaply enough to be useful as energy sources, requires high EROI, high capacity factor energy. I provided a link to an engineering study that explains all of this, but you didn't read it.
Our society was able to grow into its present form, with its high incomes, high technology and enormous sprawling infrastructure, due to the almost free energy provided by fossil fuels. Expensive energy drawn from ambient energy fluxes are entirely inadequate to the task of replacing the almost free energy of fossil fuels. The infrastructure that our society works with, only functions if energy supply remains cheap. This is why living standards in Western economies have stagnated since the 1980s.

louis · Science, Technology, and Astronomy

Well I am not particularly focussed on carbon emissions - more on sustainable green energy production of electricity as part of a wider green energy economy. I think a green energy economy will be a step forward in human development allowing energy independence for countries and even households, reducing environmental impacts across the globe and providing cleaner air in cities.

I am not making the case for major use of bio fuels. I was simply making the point that if you add bio fuels, energy from waste, geothermal, and some other green energy solutions you will, with storage where applicable, be able to provide maybe 20% of your energy requirement when wind and solar are not doing the business. Continental grids can also see you through these periods of low output.

The pattern of green energy production will vary from country to country. Some countries like Kenya and Iceland have good geothermal access, others less so. In the UK we are blessed with wind but not sun. In some countries, like Norway, hydro is plentiful.

Tidal energy requires a lot of intiial capital investment. It can also have a lot of negative environmental impact. Where it has been successfully deployed e.g. at La Rance in France, after the initial capital investment is paid off, it produces very cheap electricity - and could continue to for hundreds of years, I guess. So it has merit.

Wave energy is something that we tend to forget about. There's a lot of energy out in there in them there waves! But salt water seas are challenging locations for energy production. We may yet see a rise in wave energy production.

I think that the point about hydro is, under a green energy framework, it is no longer to be seen as a baseload and response resource, but rather as an energy storage facility. So generally speaking it would not be used to contribute to baseload (being provided by green energy plus energy storage gas) or to respond to peaks (that would be a job for chemical batteries working over 24 hour cycles) but rather would come into play during period of low green energy output. In the USA, hydroelectricity provides 6.6% of electric power. So, if it was being used for energy storage mostly, you could probably get that up to 10% or more, maybe 15%, during critical periods.

I think wind power has some inbuilt technological requirements which will mean the cost reductions begin to level off. However, I don't think we are close to the bottom of the technological price reduction curve with solar. PV film printing, robot installation and maintenance and less costly materials are all going to continue driving down the cost, together with improvements in capacity output. We really don't know where this technology will lead. With solar power aeroplanes and ultralightweight PV film, we may find ways of exploiting the perfect solar conditions above the cloud layer. Who really knows? The point is we are nowhere near the end of the solar power technology route.

Point to note: PV and wind turbines can be manufactured using green energy, potentially. In fact if you had a PV manufacturing facilitiy out in the desert, using locally sourced materials and using PV power, you would be getting close to an infinite EROI because your energy input would be getting close to 0.

Yes, propane sounds like an excellent fuel to manufacture as a storage medium. I think I tend to focus on methane because in the UK and much of Europe we already have a huge methane infrastructure - storage facility, electricity generation and pipelines direct to people's home. My understanding is propane is widely used in the USA, with people having it stored in tanks outside their home.

kbd512 wrote:

louis wrote:
It doesn't make sense for nuclear power which has periodic maintenance downtime but otherwise is pretty much producing energy at a steady rate.
Making an energy storage fuel such as hydrogen, methane or something else, make huge sense for green energy systems which are unpredictably intermittent and which produce frequent energy surpluses during which time the marginal cost of the excess energy is effectively close to zero. So you have a very cheap energy source you can use to manufacture your energy storage gas. All that needs to happen is that green energy gets so cheap that it can afford the expense of the energy storage gas manufacture to cover the periods of low green energy. Leaving aside diurnal dips you are probably talking of the equivalent of something like the equivalent of 10% of overall electricity power or 36 days. If you have significant amounts of hydro, energy from waste, bio energy. geothermal, tidal etc. you'll never be needing to produce more than probably 80% of average.
Louis,
Synthesizing Propane makes a lot more sense than Hydrogen or Methane if the goal is to create a dispatchable and readily transportable energy store. Propane is indefinitely storable as a dense liquid without cryogenic cooling, at heavy duty truck tire pressures at room temperature, unlike Hydrogen and Methane, which means common carbon steels are capable of storing the gas as a liquid.
Pumping water requires constant power output. Reactors are great at that. Wind and solar are not. Heating a chemical reactor vessel to synthesize a hydrocarbon gas or liquid also requires constant input power. Water electrolysis does not, because it's essentially a reverse fuel cell reaction that can be turned on / off at will.
According to the graphs you provided, intermittent energy is rapidly becoming about as cheap as it ever will be, using the cheapest forms of fossil fuel energy from coal and gas to produce the photovoltaics and wind turbines.
There are no "significant amounts of hydro" from dams. That energy has already been spoken for and there are few rivers left that we can dam without significant downstream impacts. What do you imagine we presently do with the energy provided by the Hoover Dam, for example?
I'm not sure why we haven't developed more power generation infrastructure to use tidal power, but it must be some kind of an engineering problem else there'd be a lot more of it.
There's been little development of geothermal power, because there's a point at which it becomes impractical to use, such as circulating water between hot and cold sinks through vertical shafts hundreds or thousands of meters in length. The hot side temperatures need to be much hotter for deep wells to function.
The "energy from waste" is also known as burning stuff. If you recycle more of the wood pulp instead, then you don't have to re-plant as many trees and more trees are available as Carbon sinks. If burning stuff that contains large quantities of Carbon is the problem, then burning even more of it is unlikely to be the solution.

louis · Human missions

I'm guessing here that there is a problem with scaling up the F9 legs. It's either to do with the additional mass during the testing phase when you are using a small number of engines (bearing in mind the legs need heavy batteries to operate) or more fundamentally the materials they have couldn't cope with the overall mass of the landing Starship.

Oldfart1939 wrote:

I'm sure that the Engineering Geniuses at SpaceX are having nightmares about landing systems. I too, find the Elon idea of catching the rockets using a tower to be a bit fanciful at this point. I'd be more concerned about landing on an unprepared field of either Martian or Lunar regolith.
The current landing legs on Falcon 9 are composite material that has a certain amount of "flex" in it's structure. At least that's what I've read on Space News.

louis · Science, Technology, and Astronomy

I've thought about this before. Mars seems a much better repository. The Moon is simply too close to Earth. A major asteroid impact, for instance. on Earth could easily devastate the Moon with richochet material as well.

I would think one of the early things we would want to do on Mars is hold copies of all major digitalised libraries, museums, patents etc from Earth on servers on Mars, in a safe location e.g. in a stable cave system.

tahanson43206 wrote:

SpaceNut ... I searched for the terms in the title and found only the Interstellar Ark post ...
This new topic is about building a repository for DNA and knowledge away from Earth, for rebuilding from scratch if that becomes necessary.
This idea has been explored on several occasions in science fiction, and I am glad to see from the report at the link below that work continues.
https://www.yahoo.com/news/building-lun … 10252.html
AZXIOS
Building a lunar ark for the human race
Bryan Walsh
Sat, March 13, 2021 10:37 AM
A team of researchers is floating the idea of creating a biological repository on the Moon for millions of species on Earth — including humans.
This idea should be of interest to the NewMars community.
The article includes references to other similar efforts.
(th)

louis · Science, Technology, and Astronomy

It doesn't make sense for nuclear power which has periodic maintenance downtime but otherwise is pretty much producing energy at a steady rate.

Making an energy storage fuel such as hydrogen, methane or something else, make huge sense for green energy systems which are unpredictably intermittent and which produce frequent energy surpluses during which time the marginal cost of the excess energy is effectively close to zero. So you have a very cheap energy source you can use to manufacture your energy storage gas. All that needs to happen is that green energy gets so cheap that it can afford the expense of the energy storage gas manufacture to cover the periods of low green energy. Leaving aside diurnal dips you are probably talking of the equivalent of something like the equivalent of 10% of overall electricity power or 36 days. If you have significant amounts of hydro, energy from waste, bio energy. geothermal, tidal etc. you'll never be needing to produce more than probably 80% of average.

Calliban wrote:

Existing fission reactors are optimised to produce bulk electricity for power grids. This will always be a more valuable product than hydrogen, because electricity has a close to 100% exergy value. That means that 1kWh of electric power will provide close to 1kWh of mechanical energy, electronic processing or high quality heat. And reactors are almost completely dispatchable, which means their output is predictable and controllable. The only way we would use reactors to make hydrogen is if the electricity market is saturated and we cannot use fossil fuel derived hydrogen more cheaply. So nuclear hydrogen production won't make sense until it has already cornered the electricity market.
One thing that nuclear power does produce already is gigawatts of waste heat, most of which is ejected into the atmosphere or into rivers. The temperature of this waste heat is about 30°C, which is far too low for district heating. However, the heat would be useful for agriculture, I.e greenhouse or polytunnel heating and it would increase both growing season and productivity. If you could build entire towns under plastic or glass canopies, the heat could eliminate the need for heating of buildings. That would be very valuable in cold climates, like Russia and Canada, where any sort of outside work is very difficult for more than half the year. Low quality heat would also be useful in vacuum desalination of seawater.
So yes, there is more that could be done with existing nuclear power plants. Waste heat accounts for two-thirds of all energy extracted from uranium in LWRs. It would be well worthwhile exploring useful applications in this area.

louis · Unmanned probes

This is for me one of the main arguments for human landings on Mars. With a team of geologists and experts in organic chemistry we'll find out more in a month than we have done in 50 years of robot landings. While it costs a lot to get a human to Mars, we have to set that against the relative cost of robot missions.

GW Johnson wrote:

Using the odd traces in the Allan Hills Mars meteorite as a guide, Martian microbes might well be smaller than their analogs on Earth. The traces in that meteorite certainly were.
Similar traces in Earthly rocks are considered to be definitive traces of early microbe life on Earth. But not those on that meteorite. Which is exactly why we have not yet discovered proof of early life on Mars.
Such traces, being billions of years old, contain no remaining organic components, there are just physical forms replaced by minerals. You recognize them by their appearance, not their chemistry. There is no chemistry left, after such a long time and so many physical processes. Which is really why you need a human geologist on Mars.
The other more common physical trace of microbial life is the rock type we know as "stromatolite". These are layered carbonate rocks, of marine origin, not so much freshwater lacustrine. These are formed by a mat of microbes depositing layer after layer upon the original substrate rock. The layered form of bulbous rock "heads" is what you look for. After billions of years, all is replacement minerals, no organics remain.
Perseverance might or might not find such stromatolite rock forms in Jezero crater. While there was a persistent lake there around 3 billion years ago, it may not ever have been salt water. Here on Earth, the stromatolites are all saltwater marine formations. Although Mars could easily have been different. Again, you do NOT find this stuff with chemistry. You find it by its physical appearance. A human geologist can easily do that. A robot's camera cannot. Not at this time in our history.
There is a glacier in more than one crater on Mars. That is a different environment from what I have been discussing. There, you would not be looking for rocky fossils, but for preserved organic materials embedded in the ice. A robot with chemical analysis capability has a decent chance to find such traces.
There would appear to be no such ice in Jezero crater. But there's a lot of sediments, and a lot of rocks.
GW

louis · Human missions

I think there is a consensus here at least that of the three - Earth, Moon and Mars - a rough landing on the Moon would be the most demanding. I only mention Earth as I presume Space X would be carrying out test rough landings on Earth.

Oldfart1939 wrote:

Great work, GW!
I think that SpaceX hasn't come to grips entirely with the rough landing area problem. This is going to be worse on the Moon than on Mars, in my estimation. They seem to be in the stage of not knowing or realizing what they don't know, but aren't letting that slow them down to a snail's pace. They not only need the landing leg design to be realistic, but also have sufficient ground clearance for the Raptors bell nozzles to have clearance.
SpaceX has adequately addressed the effects of rocket exhaust on lunar regolith by using the "puller versus pusher" concept, similar to the early Hermann Oberth and von Braun "Repulsor" designs, as well as early Goddard rockets. Blasting small rocks into weird orbits is NOT a good idea!
Any way, we live in an exciting time for space nerds.

louis · Unmanned probes

Excellent idea. The only problem I see with the project would be that robot missions seem to have such long lead in times, I think Space X will be on Mars already and looking into such matters - though I suppose Space X might be less keen on discovering life if it's going to hold up colonisation...

Quaoar wrote:

Hi to all,
After the futuristic laser sail-starship, I would like to talk with you about something of more easy to do in the next years: an unmanned probe able to land on a glacier in an unnamed crater of the Vastitas Borealis (70.5° North and 103° East).
https://www.esa.int/var/esa/storage/ima … rticle.jpg
The lander will have a probe with an electric resistance able to melt the ice, penetrate for a meter or two, then aspirate some water samples, examine them with a microscope and send the images to Earth. Bacteria-like microbial life forms can be detected easily with a simple microscope (if we see no bacteria the probe can also make a culture incubating the water with organic material for some days). If the final result is positive, we can plan a sample return mission in the same place.
Just one bacteria-like alien organism can answer many of questions that torment the astrobiologists from years: is DNA the only possible genetic information-barer material for all the life forms, or in other planets the natural selection might have chosen other informational molecules (TNA, GNA, PNA are only example)?
https://en.wikipedia.org/wiki/Threose_nucleic_acid
https://en.wikipedia.org/wiki/Glycol_nucleic_acid
https://en.wikipedia.org/wiki/Peptide_nucleic_acid
There are hundreds of amino-acids, but the DNA of all the Earth's life forms uses only 20 of them as the building block of the living being. Is that choice ubiquitous, or there are alien organisms using completely different amino-acid sets?
I would like to know an expert opinion on the feasibility.

louis · Science, Technology, and Astronomy

Never read such tendentious nonsense.

1. SARS did not arise as a result of industrialised farming.

2. Chinese peasants in common with poor peasants across the world live cheek by jowl with their animals. Diseases are crossing the species "barrier" all the time - it's just a question of why only a few are successful.

3. Old people's lungs - well all lungs really - are an environmental niche, a pretty easily accessible one as well. Getting into the lungs is a lot easier than getting through the skin barrier. But old people's lungs are particularly inviting for pathogens because they are poorly protected (less effective immune system) and often diseased in a more general sense, ie not functioning properly.

4. Please don't confuse anti-viral drugs with vaccinations. Mass vaccination does not address only the needs of sick people. It is mass medication of mostly healthy people.

5. You say flu has been with us for 8000 years but it has been subjected to a mass vaccination eradication campaign for a couple of decades now. In the UK in mid Feb this year, despite 600,000 sample tests not a SINGLE case of flu had been detected sice the beginning of the year! That's truly unprecedented.

6. I don't know what your scientific qualifications in this regard are but many scientists do believe SARS got a hold because of the impact of the flu vaccination campaign. It's just you never hear from them in the MSM.

7. You do know the Astra Zeneca vaccine has just been withdrawn from use in at least 12 countries because of concerns re blood clot effects?

8. You have this insane idea that a very old person has the Covid vaccine, then doesn't get Covid or die from the demands of the vaccine on their system (neither guaranteed) and afterwards goes on to enjoy an extra year or two of rosy twilight years in perfect health. This is nonsense. If Covid is going to cause your death, your immune system or your body more generally is already pretty compromised. If you protect very old people with weakened immune systems from a respiratory pathogen death it is likely they will die of something like sepsis, which may involve amputation of limbs, or Alzheimers so losing contact with family and reality more generally, or Parkinsons - ending in a total shutdown of functioning - or cancer with all its pain and unpleasant complications. You are essentially depriving old people of a dignified exit.

kbd512 wrote:

Louis,
Influenza vaccinations did NOT cause COVID-19. Not vaccinating against influenza would not have stopped COVID-19, nor vice versa. The two viruses have little to do with each other. The newer SARS-like avian and bat viruses have become increasingly serious problems for other mammals over the past century. Prior to the last century, there were no industrialized farming operations capable of quickly spreading pathogens between vast numbers of animals and humans. Influenza, on the other hand, has been with us for at least 8,000 years. The use of medical technology such as anti-viral drugs and vaccinations to prevent serious illness is NOT cheating anyone or anything, either. It's improving the quality of life for millions or even billions of people. Humanity has already paid a high enough price to get to where we are today, and there's no reason to regress to satiate the fears of people who don't understand vaccines and refuse to do so.

louis · Human missions

Those are stubs not legs! lol

SpaceNut wrote:

Sn11 on the pad waiting
https://www.nasaspaceflight.com/2021/03 … ns-future/
Can just barely make out the legs

louis · Human missions

As I said on the other thread, Felix of WAI is taking Elon's comments serious about the rocket-catcher set up. It certainly could make sense for a landing on a prepared flat pad because you might then dispense with the legs. But couldn't work for a first time landing on the Moon or on Mars.

SpaceNut wrote:

Thanks as I am on a cellphone at this time.
Repost
Oldfart1939 wrote:
Robert--I recall seeing something about a crushable portion in these new legs. A one-time use expedient. Some of the more fanciful comments by Elon are about catching the Starship instead of using landing legs. But--not here yet, and not "now."

louis · Human missions

Felix of WAI seems to thinking Elon is deadly serious about the rocket-catcher. But that would only work with perfectly flat concrete landing pads. He will still need legs to land on the Moon or Mars.

Oldfart1939 wrote:

Robert--I recall seeing something about a crushable portion in these new legs. A one-time use expedient. Some of the more fanciful comments by Elon are about catching the Starship instead of using landing legs. But--not here yet, and not "now."

louis · Science, Technology, and Astronomy

https://www.youtube.com/watch?v=DB_zSKJDGpU

Good to hear.

louis · Human missions

Good update from SpaceXcentric:

https://www.youtube.com/watch?v=qOy3G0Axy3I

louis · Science, Technology, and Astronomy

Not sure if this relates directly to what has been discussed so far, but don't we also have the opportunity on Mars of using CO2 as the equivalent of a steam engine with condenser without having to deploy additional energy. It can be fine tuned with use of solar reflectors during the day. If placed near or within a settlement you might be able to run it at night off the ambient heat of the settlement.

louis · Science, Technology, and Astronomy

106 metre blades.

Not sure where you get the 1,600 MW figure from - it's 14 MW capacity. Annual elecriticity production is more than enough to power the whole of the UK for one hour!

https://www.ge.com/renewableenergy/wind … re-turbine

SpaceNut wrote:

This thing is hugehttps://img-s-msn-com.akamaized.net/tenant/amp/entityid/BB1bxtRp.img?h=488&w=799&m=6&q=60&o=f&l=f
1,600 megawatts of offshore wind electricity

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