Supercapacitors

tahanson43206 · 2019-11-07 19:13:40

For SpaceNut .... Following Louis' lead, here is a new top level topic devoted to supercapacitors

Supercapacitors are mentioned in several posts in the NewMars archive, but not an overwhelming number, and no topic had anything to do with the subject.

I've been interested in supercapacitors for some time, but the power storage capacity has been so limited, and the cost for that storage has been so high, that I decided to wait to see if anything comes out of research.

In the article at the link below, there is news of a collaboration between MIT and Lamborghini to outdo Lithium Batteries.

This is one of many similar reports:
https://www.greencarreports.com/news/11 … l-car-ever

My takeaway from scanning several articles is that progress HAS been made, but the total amount of storage achieved is still a small fraction of what is required for a practical long range electric vehicle.

(th)

louis · 2019-11-07 19:26:25

An interesting topic area...but not one I can add anything to!

SpaceNut · 2019-11-07 21:45:51

Kbd512 has a great knowledge of these devices and has talked about how they can be used in several unique ways. What supercapacitors do well is store energy with the design being the undoing of how long it will last. The capacitor is a resistive time constant discharge device so when solving for the time span of use you need to know the current bleed off rate so that one can solve for the resistance that it represents. What makes them quite useable is that the capacitance in parellel adds up to a high level of storeage in a small space.

tahanson43206 · 2019-11-08 05:09:11

For Louis re #2 ...

Thank you for your interest in this topic. Because of your wide range of interests, with (what I believe to be) a particular focus on solar power solutions for the Mars adventure, I'd like to invite you to keep an eye out for news in this field. It ** should ** have a positive impact on overnight storage costs. My impression is that deterioration of the chemical makeup of a supercapacitor is much less than is (reported to be) true with batteries of any kind.

For SpaceNut ... You've raised an interesting point, but from my perspective, the storage bleedoff of supercapacitors has not been made public (at least where I've been looking). If you can find anything about that particular aspect of this technology, I'd definitely be interested.

(th)

Calliban · 2019-11-08 05:41:23

Low energy density: about a fifth to a tenth that of a lead acid battery. But a very high discharge rate, leading to very high power density.

https://en.wikipedia.org/wiki/Energy_density

Useful for smoothing power transients, but not so good for bulk energy storage. If you are relying upon diesel backup for a small wind turbine and you need a few minutes to start it and run it up to speed, supercaps are a good option for smoothing the transient and avoiding tripping the system by frequency drop, because of their high and rapid discharge rate.

They could be useful in regenerative braking as well, where modest amounts of energy are needed to accelerate a vehicle, delivered at high power. Engines, fuel cells, nuclear reactors; all require finite time to start or change power level, as they require fluid injection (fuel and cooling) and have mechanical and thermal inertia.

Supercaps are also frequently discussed as components for rail guns, coil guns and direct energy weapons, where very high discharge rates are needed. They would be useful components in mass drivers.

Last edited by Calliban (2019-11-08 06:09:47)

tahanson43206 · 2019-11-08 06:52:58

For Calliban re #5 ...

Thank you for adding to this topic!

I agree that (from all I have read so far) supercapacitors have a lower power density than batteries, but I'm not sure (at this point) if the difference is by volume or by weight. Please comment upon this quote from the article:

The Sián's 48-volt e-motor, built into its transmission, uses a supercapacitor as its power reserve. Lamborghini has not provided the exact specifications for its supercapacitor, but it has revealed that it's three times more powerful than a lithium-ion battery of the same weight.

I'm unsure of the meaning of "powerful" in this context.

The comparison of weight is a useful marker.

The implication might be that for an aircraft with volume to spare, a supercapacitor of this new design might be able to store three times as much "power" as a comparable set of lithium batteries, without the risk of fire, or (presumably) the cost of materials.

That last is another point of uncertainty, since the materials used for the new capacitor are not revealed.

An aircraft type with "volume to spare" would be lighter-than-air craft.

I've seen no reports of electric propulsion for lighter-than-air craft, but that certainly doesn't mean folks aren't working on them.

(th)

Calliban · 2019-11-08 07:18:37

tahanson43206 wrote:

For Calliban re #5 ...
Thank you for adding to this topic!
I agree that (from all I have read so far) supercapacitors have a lower power density than batteries, but I'm not sure (at this point) if the difference is by volume or by weight. Please comment upon this quote from the article:
The Sián's 48-volt e-motor, built into its transmission, uses a supercapacitor as its power reserve. Lamborghini has not provided the exact specifications for its supercapacitor, but it has revealed that it's three times more powerful than a lithium-ion battery of the same weight.
I'm unsure of the meaning of "powerful" in this context.
The comparison of weight is a useful marker.
The implication might be that for an aircraft with volume to spare, a supercapacitor of this new design might be able to store three times as much "power" as a comparable set of lithium batteries, without the risk of fire, or (presumably) the cost of materials.
That last is another point of uncertainty, since the materials used for the new capacitor are not revealed.
An aircraft type with "volume to spare" would be lighter-than-air craft.
I've seen no reports of electric propulsion for lighter-than-air craft, but that certainly doesn't mean folks aren't working on them.
(th)

Power is a measure of energy delivered per unit time. Super capacitors are far more powerful per unit weight than chemical batteries, as they do not need to rely upon chemical reaction kinetics between a reactant and a surface. They just discharge stored charge. This makes them useful for driving the acceleration of a vehicle, where modest amounts of energy need to be delivered in a very short time.

Energy density is a measure of total energy stored per unit mass or volume. By this measure, super capacitors are inferior to practically any chemical battery, which is in turn inferior to any IC engine. A pure supercap powered vehicle would have awesome acceleration, but pitiful range.

By the same measure, explosives have enormous power density, because their stored energy is released in milliseconds. But their energy density is typically an order of magnitude lower than chemical fuels.

Last edited by Calliban (2019-11-08 07:24:56)

Calliban · 2019-11-08 07:33:34

tahanson43206 wrote:

I've seen no reports of electric propulsion for lighter-than-air craft, but that certainly doesn't mean folks aren't working on them.
(th)

Airships generally have greatly superior performance compared to aeroplanes, in terms of MJ/tonne-mile. The price to pay is much lower speed ~100km/h.

In terms of power requirements, from memory, the Hindenburg was powered by four diesel engines with power about 800kW each - so that's about 3.2MW at cruising speed. By contrast, a 747 at take-off needs about 200MW, with somewhat less power when it reaches cruising speed.

So a large airship needs not much more than 1% of the power of large jet, but it must be sustained for a lot longer. Probably a good candidate for compact passively safe nuclear reactor. We aren't so bothered about power density, but energy density needs to be high for long trips, as fuel mass eats into payload allowance. By contrast, a nuclear powered aeroplane would require a reactor producing 100+ MW of thrust power; the mass of shielding makes it impractical.

When the world starts to run short of liquid fuels and jet travel becomes expensive, airships powered by compact modular reactors are a very workable alternative, at least from an operational perspective. Politics is always another matter.

Last edited by Calliban (2019-11-08 07:40:45)

louis · 2019-11-08 08:21:35

A 747 can carry well over 400 passengers...whereas the Hindenburg carried 50...so you'd have to multiply your 3.2MW by 8 for a fair comparison I would say, in terms of the energy required to carry x no. of people.

Calliban wrote:

tahanson43206 wrote:
I've seen no reports of electric propulsion for lighter-than-air craft, but that certainly doesn't mean folks aren't working on them.
(th)
Airships generally have greatly superior performance compared to aeroplanes, in terms of MJ/tonne-mile. The price to pay is much lower speed ~100km/h.
In terms of power requirements, from memory, the Hindenburg was powered by four diesel engines with power about 800kW each - so that's about 3.2MW at cruising speed. By contrast, a 747 at take-off needs about 200MW, with somewhat less power when it reaches cruising speed.
So a large airship needs not much more than 1% of the power of large jet, but it must be sustained for a lot longer. Probably a good candidate for compact passively safe nuclear reactor. We aren't so bothered about power density, but energy density needs to be high for long trips, as fuel mass eats into payload allowance. By contrast, a nuclear powered aeroplane would require a reactor producing 100+ MW of thrust power; the mass of shielding makes it impractical.
When the world starts to run short of liquid fuels and jet travel becomes expensive, airships powered by compact modular reactors are a very workable alternative, at least from an operational perspective. Politics is always another matter.

Calliban · 2019-11-08 09:06:16

louis wrote:

A 747 can carry well over 400 passengers...whereas the Hindenburg carried 50...so you'd have to multiply your 3.2MW by 8 for a fair comparison I would say, in terms of the energy required to carry x no. of people.

Of course Louis. I reference the Hindenburg only as a very loose example of engine power needed. We would not replicate it precisely today. Frames would be built from carbon fibre reinforced polymer instead of aluminium; gas cells probably the same and the outer cover some sort of fibre reinforced polymer. We would also use CFD and CAD to determine a more optimised shape. All in all, a modern rigid the size of the Hindenburg would carry a lot more passengers. But I think freight is a more likely use for such a vehicle.

Hydrogen would still have to be used as lifting gas. There isn't enough helium on the planet to roll out the airship as a mass market solution in the quantities needed.

The undoing of the airship is its slow speed. Not only is this inconvenient for passengers, but it means that an airship will deliver far fewer passenger miles than a jet aircraft of comparable capacity in its lifetime. To put it another way, a 747 carrying 400 passengers, could cross the Atlantic perhaps 5 times (2000 passenger journeys) in the same time as it would take any airship to cross it once (400 passenger journeys). Unless fuel is very expensive, it will be difficult for an airship to compete, as both options have capital costs.

Last edited by Calliban (2019-11-08 09:12:07)

Terraformer · 2019-11-08 09:49:57

The Hindenburg wasn't configured for cheap travel, though. Take out the staterooms and replace them with budget suites, and I'm sure it could have fit far more than 50 people.

tahanson43206 · 2019-11-08 15:01:14

For Calliban re topic ...

Thanks (again) for moving this topic ...

I wonder if you could try again? For some reason I'm not picking up on your argument.

My question regarding air ship power was based upon the MIT/auto company claim that they are able to deliver a given amount of power for 1/3 the weight of a comparable lithium battery. That would suggest that a small airship (runabout size) could be powered by supercapacitors.

Some years ago I read about the early experiments with hydrogen blimps for one person transport by ? Dumas ? in Paris. A comparable vehicle today would be far superior in many ways, and it would be a nice touch to power the propulsion system with an electric system.

Fuel cells would certainly be an attractive solution, as kbd512 has reminded the forum on several occasions, but I am intrigued by the prospect of "refueling" rapidly and flying for extended distances in the comparative safety of a lighter-than-air vehicle.

Specifically, if the supercapacitor solution weighs LESS than lithium batteries, then the VOLUME of the storage system should not be a problem in a lighter-than-air vehicle, so the number of supercapacitors needed for long range could be incorporated into the design.

Unfortunately, I suspect there is insufficient information available to make an educated guess.

The critical missing piece (may be) the volume of the supercapacitor system compared to the lithium battery solution able to deliver the same power.

(th)

SpaceNut · 2019-11-08 17:58:45

Capacitors are a set of plates seperated by a dielectric that allow the charge to be stored. The plate sizes effect the amount of storeage or capacitance value.
When the capacitors are connected in parellel the values of the capacitor add up such that you are storing more energy.

tahanson43206 · 2019-11-08 18:28:39

For SpaceNut re #13

Thank you for the reminder of the nature of traditional capacitors. I felt the need to try to understand (at little bit better at least) the difference between traditional capacitors and "supercapacitors".

There is a WikiPedia article which seems to be tackling the problem of explaining the difference:
https://en.wikipedia.org/wiki/Supercapacitor

Forum readers are invited to take a look at the section of the article which compares ordinary capacitors (as described by SpaceNut) and supercapacitors.

An interesting feature of supercapacitors, which I do not yet understand, is "double capacitance".

(th)

tahanson43206 · 2019-11-08 20:57:43

Following up on the side track of electrically powered dirigible, I asked Mr. Google to find any notes that might exist on the subject.

The Tissandier brothers’ dirigible was the first to be powered by electricity. A 1.5 horsepower Siemens electric motor, turning 180 r.p.m., drove a two-bladed propeller through a reduction gear, producing 26 pounds of thrust (116 newtons). 24 bichromate of potash (potassium bichromate) cells provided electricity for the motor, which propelled the airship at 3 miles per hour (4.8 kilometers per hour).
The airship was 28 meters (91 feet, 10 inches) long with a maximum diameter of 9.2 meters (30 feet, 2 inches). Its gas capacity was 1,060 cubic meters (37,434 cubic feet). The total weight of the airship, with “two excursionists,” instruments and ballast, was 1,240 kilograms (2,734 pounds).

This record from 1883 was found at:
https://www.thisdayinaviation.com/tag/t … c-airship/

Wikipedia has an article about the Tissandier brothers:
https://en.wikipedia.org/wiki/Albert_Tissandier

Bringing the post back to Supercapacitors ... I'd like to think a 2019 version of that 1883 experiment would be able to move at a slightly greater speed than 3 miles per hour.

(th)

tahanson43206 · 2019-11-09 06:53:48

A potential driver of supercapacitor research is market demand.

NASA has been working on an electric airplane since 2015, according to the article at the link below.

https://www.yahoo.com/news/nasa-unveils … 07127.html

Due to current battery limitations, the Maxwell's design is envisioned for use in short-haul flights as an air-taxi or commuter plane for a small number of passengers. (Additional reporting and writing Steve Gorman in Culver City, Calif.; Editing by Sandra Maler)

I'm intrigued that the NASA team (apparently) decided NOT to pursue fuel cell technology. Perhaps at the time planning was underway to establish the scope of the project, fuel cell (and fuel supply) technology was not thought to be far enough along.

It seems (to me at least) likely that the ubiquitous availability of utility scale electric power may have swung the balance toward lithium batteries.

It will be a while (if ever) before Hydrogen (or even Ammonia) becomes available at a comparable level.

(th)

SpaceNut · 2019-11-09 10:11:25

The mass of tanks is considereable when compared to the supercapacitor which has electrolyte with simulate to fuel cell membrane materials making it sort of a hybrid depending on construction to being a battery as well. The making of supercaps in multiple plate wraps with different materials between them allow for the change in how they function for power delivery.
One of the first version of supercaps were made for use as a memory keep alive circuit power source for critical data when power failures occur where the demand if micro current level.

tahanson43206 · 2019-11-11 07:39:33

The announcement of successful research at the link below should be of interest to those in the forum who are supporting the idea of using aerogel for various applications. By using aerogel the researchers have (apparently) greatly increased the capacitance of a new design for a supercapacitor.

The link also reports on the use of carbon nanofilm in the fabrication of the material incorporated into the material.

https://phys.org/news/2017-07-team-fast … citor.html

(th)

SpaceNut · 2019-11-11 14:13:33

Copied multiple posts to the topic Autonomous Passenger Carrying Electric Aircraft by kbd512 as it relates to the use there in.

kbd512 · 2019-11-12 22:36:53

tahanson43206,

The most advanced super capacitors in commercial production have energy density (specific energy) in line with Lead-acid batteries. However, these are still pretty expensive and applications remain limited. Tesla Motors Corp purchased Maxwell for this technology. Some dev lab 3D super cap technology has reached energy densities as high as 110Wh/kg, or a little less than half of what a commercial Lithium-ion battery can store. It's an interesting technology for providing bursts of power for very brief periods of acceleration for motor vehicle applications, but not so interesting for powered flight applications which have high constant power requirements. Trying to power any type of aircraft with Lead-acid batteries isn't very practical.

Super capacitors are capable of dumping stored energy at rates that would destroy Lithium-ion batteries. A super capacitor bank is a good way to put less wear and tear on a Lithium-ion battery bank from very high discharge rates (for a battery) associated with very brief periods of acceleration measured in seconds. The battery only has to recharge the capacitor bank and maintain a comparatively minor constant output level to move the vehicle at highway speeds (10hp to 20hp for most passenger vehicles in the 1t to 3t range). So long as ranges of hundreds of miles are not required, you can make a battery powered motor vehicle lighter and cheaper because you don't need extra battery capacity just to deal with high discharge rates. The same concept would apply to combustion engine vehicles. If a vehicle was powered by a combination of super capacitors and a piston engine powering a generator, then a very low displacement engine combined with a super capacitor bank would be sufficient to accelerate the vehicle acceptably well and run it at highway speeds without requiring additional engine power for acceleration. A free piston engine with a super capacitor bank would be ideal, I would think.

In powered flight applications that use aerodynamic lift to remain airborne, weight is what matters most, followed rather closely and synergistically by aerodynamics. In short, weight affects power requirements through aerodynamics. You have to produce sufficient power to propel the wing and everything attached to it through the air fast enough to produce the "up force" required to keep some specific amount of weight airborne at some specific speed. The power requirement doesn't linearly increase with increasing speed, either. That's why you design an aircraft to cruise at some optimum speed, with a given load, to a given distance.

The only way to meaningfully improve performance is to increase power, decrease weight, or improve aerodynamics- dependent upon what you're trying to accomplish. Most aircraft designers do pay attention to the drag generated by their airframe design and try to minimize it for a particular cruising speed. It's a balancing act to manage the inverse relationship between induced and parasitic drag to minimize total drag for a design cruise speed. If you want more speed, then you need more power. That means you need a bigger and heavier engine that consumes more fuel. You'll need a heavier airframe attached to that bigger engine and bigger gas tanks carrying more gas. Whether the "gas" is gasoline, kerosene, diesel, methane, hydrogen, or electrons stored in a battery or capacitor is irrelevant to the design goal of "going faster". You're going to consume more of "it" to go faster. Period. If the fuel is electrons wirelessly transmitted via microwave, that's the only practical way I know of to offload the weight of the "gas" and gas tank. It's going to be a compromise (prioritization) of some kind.

To actually get some specific mass airborne using aerodynamic lift, you must accelerate the wing (and everything attached to it, obviously) fast enough to fly before you run out of available runway, with performance margin to spare. As a result, you'll briefly need to generate some multiple of the amount of power minimally required to simply remain airborne in level flight. There's obviously a limit to this, since aircraft can take off vertically when thrust is greater than weight. Generating that kind of power leads to very heavy engines with very high fuel consumption. There's no such thing as a helicopter that's more fuel efficient than a fixed wing aircraft carrying equivalent payload to equivalent distance at equivalent speed, for example.

To overcome drag to fly significantly faster without a dramatic increase in power, it's certainly possible to attach tiny wings that only produce sufficient lift to get airborne at high speeds. However, that typically results in unmanageable takeoff and landing speeds that would impart very high forces into the airframe from all but the most perfect landings. That would then mandate a very robust design which requires more structural weight to achieve, which then requires more wing to lift it, which then requires more power to push the craft through the air.

Now that we understand why it is that aircraft power plants must be lightweight and consume energy stores with very high energy densities per unit of weight, let's consider the use of an energy store with half of the performance of current Lithium-ion batteries. In practice, we're going to drastically reduce payload or range or speed, or likely all three, by using a very low energy density storage technology. Alternatively, we're going to drastically increase the size and weight of any solution competitive with a gas or kerosene engine, and therefore cost. The energy density issue is an intractable problem, as it pertains to powered flight. However, if we're willing to trade speed for total delivered tonnage for a given fuel burn, there are certainly practical alternatives to gas turbines and high fuel burns, principally by using a lifting gas to negate part of the power requirement simply to remain aloft.

Modern transport airships are also designed to use aerodynamic lift to remain airborne. To aid controllability in flight, these airships are slightly heavier than air. They use speed to vary the amount of lift generated by the inflatable structure to ascend or descend, just like conventional fixed wing aircraft. The power requirements are lower per unit of mass since less lift is required and lower speeds are involved. However, moving weight around at highway speeds (60mph to 120mph) and pushing all of that air out of the way still requires a certain amount of power. The volume of air being displaced by a large cargo transport will closely resemble that associated with an aircraft carrier, so the power requirement is still non-trivial. Lockheed-Martin designed a cargo airship to use a type of "inflatable suction cup" (reverse hovercraft technology) to glue the blimp to the ground for cargo loading / offloading, negating the need for any sort of specialized ground equipment for cargo transfer.

There are 3 practical applications I see for this technology:

1. Faster commercial cargo transport with less energy consumption than jet aircraft and therefore cost. An airship will be significantly faster than ocean-going cargo ships while consuming less fuel to achieve the same range with a given payload than a traditional jet airliner.

No dredged shipping channels or docks equipped with gigantic cargo offload cranes are required, so a simple concrete slab with forklifts and CONEX box cranes is all that's required to offload cargo. The infrastructure and embodied energy cost, since it takes energy and money to mine ore, smelt steel, machine the steel into complex cargo transfer equipment, transport it to the dock site and maintenance costs for all of that stuff are drastically reduced.

Fewer crew are required to man airships, perhaps just 2 to 4 pilots, no different than other commercial aircraft. To ferry cargo across the Atlantic, from New York to London, the Airlander 10's 90mph cruising speed would equate to a 38 hour flight. The Airlander 50's projected to have a faster cruising speed of 120mph, so that's a 29 hour flight. The more economical alternative is a 6 to 12 day journey by cargo ship. That may not matter for furniture or raw materials, but it matters greatly for food / medicine / aircraft parts. A Boeing 747 can complete the same journey in 6 hours, but with a 22,000 gallon fuel burn. The Airliner 50 would burn around a quarter as much fuel to deliver the same tonnage of cargo the same distance.

2. The "Knarr" concept, which uses a solar panel and regenerative fuel cells, wouldn't "burn" any fuel that couldn't be recycled, so the fuel consumption and thus cost drops to near zero. It's larger than our largest aircraft carriers, but also carries 1,000t of cargo at roughly the same speed as the Airlander 50. The Knarr only requires 5,600hp to do that. It's covered with 63,000m^2 worth of thin film solar panels to generate around 12MW of power at noon. To put this in perspective, our Osprey tilt rotor aircraft are equipped with a pair of 6,150shp Rolls Royce T406 gas turbines. The Osprey's maximum vertical takeoff weight is 24t. So, Knarr's cargo capacity is equivalent to 41 Osprey's loaded with gas and cargo to their maximum vertical takeoff weight. If it's not obvious, helicopters really suck at energy efficiency when compared to fixed wing aircraft or blimps, though they still have their uses.

A single Knarr could deploy a full strength US Armored Company (M1 Abrams MBT's) per flight. Two squadrons of Knarr's could deploy a full strength US Armored Division (again, our MBT's, not lighter APC's / IFV's) to Europe in approximately 2 days, and we could skip the railhead and pier side RORO operations entirely, so everything would arrive in theater much faster than rail / shipping operations.

3. Airships could act as sky cranes to deliver cargo that would be impractical to deliver by other methods, such as gigantic wind turbine blades and materials for skyscrapers. Affordable high capacity vertical lift would be an enabling technology for building all sorts of structures. Cranes would still have their uses. However, if we were building mile-high skyscrapers, then it'd be a whole lot easier to lower materials to workers waiting below than it would be to hoist them from the ground using cranes with the mass and support structure required to prevent them from toppling over. There's going to be some kind of practical limit on everything.

So... Super caps for airships in the immediate future? Maybe, maybe not. Perhaps only for take-off power. Giant airships for cargo transport? That'd definitely fulfill an actual "need" use case. Airships are likely more expensive to operate than ocean going cargo ships, but much faster and a lot less expensive to operate than a jet aircraft. Airships are the only type of aircraft that could make practical use of solar power, since all other forms of powered flight require far more power in a more compact package. Over time, the use of solar panels and fuel cells to lower fuel costs could lead to justification for "air mailing" nearly everything but raw materials and fuels, especially since the airship can go just about anywhere big enough for it to take off and land without any specialized support infrastructure. Time is still money in business, so we're unlikely to see airships providing passenger service. Luxury cruise liners might be an exception to that rule. The US military would immediately benefit from airships, given the total tonnage of stuff they have to move half way around the world. Disaster relief would greatly benefit from high capacity vertical lift and no requirement for functional airfields, and perhaps not even a place to land.

tahanson43206 · 2019-11-13 07:43:25

For kbd512 re #20

Thank you for your detailed reply in this topic. I am looking forward to studying it carefully after what pass for "morning chores" around here.

SearchTerm:Supercapacitors Author:kbd512

(th)

Last edited by tahanson43206 (2019-11-13 07:44:01)

tahanson43206 · 2019-11-15 18:53:59

For kbd512 re #20

A bit of free time opened up here, so I read #20 carefully.

I think it could be posted at luf.org without changes.

I'd appreciate your approval for me to do that.

Blog posts at luf.org require a title.

Here is a suggestion: Supercapacitors for Airship Propulsion with Background

That's not ideal, of course ... but it's a starting point for revision.

With your approval, I'd open the quote with a brief statement to the effect that the NewMars.com/forum member who publishes as kbd512 has written technical essays on a wide range of topics. The following is a recent example.

(th)

tahanson43206 · 2019-11-15 19:04:33

For kbd512 re #20

This post is about the document itself, and specifically about the potential of supercapacitors to power airships.

My intuition is that there is a sweet spot for a designer, given choices about lifting gas, airship structural material, motor selection and power source.

There may be a way to plot a graph with multiple variables, to visually spot any potential sweet spot, or perhaps, less happily, to see that lines do NOT converge.

Assuming for a moment the example you gave of a supercapacitor with half the energy density of a lithium battery, and using the MIT/auto company example cited earlier, which reported the weight of supercapacitors as being 1/3 the weight of lithium batteries with equivalent storage capacity, I would deduce that a power supply for an airship might consume twice the volume as a lithium battery system, but consume 1/3 the weight.

How that system would compare to a traditional petroleum fueled power system is a question, but for the moment, I'm assuming the advantages of electric propulsion are great enough (for a particular customer) to justify the investment.

Thanks again for your detailed reply!

(th)

SpaceNut · 2019-11-15 19:45:50

This is where you look to design the supercaps into other forms and shapes such as the wings in order to make the mass you need for them do double duty such that you continue to reduce the mass of the air ship.

tahanson43206 · 2019-11-15 20:29:27

For SpaceNut re #24 .... I like your creative thinking here ... Please consider how the basic idea, of designing supercaps into forms and shapes might take effect in housing.

A foot thick wall of supercapacitor electrical storage might be able to hold enough power to sustain a home for a period of time until main power is restored.

Such a wall might have useful thermal properties as well.

And (come to think of it) such a wall might hold power collected during the daylight hours by solar panels on the roof and in the yard.

(th)

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