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#1 2019-12-02 19:06:34

louis
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From: UK
Registered: 2008-03-24
Posts: 5,176

Power to gas - the next step

This guy's analysis is v. much my own.

https://www.carboncommentary.com/blog/2 … hxegtd41n0

Power to gas is the way forward to achieving green energy and energy independence. Manufacturing gas is much cheaper and efficient in terms of energy density than manufacturing and managing chemical batteries.

Marginal cost economics means that it is v. likely we could already start manufacturing methane at v. low cost when wind and solar are in over-supply. It would be a win-win situation, allowing us to make use of v. cheap renewable energy to drive the methane manufacturing process.

Even if the marginal cost of manufacture is still above the average cost of electricity generation, it may nevertheless be economical if it allows wind and solar to expand, assuming they are now in many cases the cheapest form of energy, since it addresses the problem of intermittency.

Last edited by louis (2019-12-02 19:23:52)


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#2 2019-12-02 19:40:29

SpaceNut
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Registered: 2004-07-22
Posts: 16,726

Re: Power to gas - the next step

When you store the energy as a function of a carbon containing fuel are we any better? The claim is the intake of others exhaust co2 for doing this so its at a loss of energy to start the process. Which is the issue for mars as well in that we must expend energy to get the fuel. Next is the selection of a water source salty or fresh to which more energy must go in to break the bonds in order for it to be used with the co2 to make the fuel in any carbon based form.
excess energy - co2 capture - co2 bond breaking - h20 breaking to create fuel sabetier to store and co2 waste gas when used and unless we are feeding this into the next reuse as its a loss once more....its an energy losing cycle.....with the only possible green is a possible lowering of atmospheric co2

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#3 2019-12-02 20:09:49

louis
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From: UK
Registered: 2008-03-24
Posts: 5,176

Re: Power to gas - the next step

It's a matter of economics, not efficiency or even carbon emissions.  Wind and solar on Earth  often produce huge surpluses of energy that have to be earthed as they are of no use to the grid. The price of such energy is negative, zero or close to zero.

The energy is there, it just has no use at present and is therefore virtually free. 

Methane manufacture means you take that free or cheap energy and use it to produce an energy source that can be stored - that immediately gives it a high value as something that can be used as baseload generation in the grid. It's a very neat fit.

On Mars, certainly in the early stages of settlement, we don't have to worry so much about price. The key questions are energy security (knowing we won't run out), labour input and matching other colony requirements.

I think methane manufacture meets the demands of Mars settlement as well. It provides complete energy security, ensuring power is available even through the worst dust storms. Methane manufacture will not require large amounts of labour input (in contrast to nuclear power). Finally, it is a good fit because we have to produce methane in any case for return flights of the Starship and local rocket flights.  So essentially we are simply skimming off some of that production (oxygen as well as methane).



SpaceNut wrote:

When you store the energy as a function of a carbon containing fuel are we any better? The claim is the intake of others exhaust co2 for doing this so its at a loss of energy to start the process. Which is the issue for mars as well in that we must expend energy to get the fuel. Next is the selection of a water source salty or fresh to which more energy must go in to break the bonds in order for it to be used with the co2 to make the fuel in any carbon based form.
excess energy - co2 capture - co2 bond breaking - h20 breaking to create fuel sabetier to store and co2 waste gas when used and unless we are feeding this into the next reuse as its a loss once more....its an energy losing cycle.....with the only possible green is a possible lowering of atmospheric co2


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#4 2019-12-02 20:15:01

SpaceNut
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Re: Power to gas - the next step

The energy is being paid for by those that connect to the grid as supplies as they gamble on that surplus... its the reseller thats over charging for its use....
Changing that game is the solar company which is not selling it all to the gamblers as they are saving it for later but its at a hugh conversion loss...
The only other way that its being done is to destabilize real gas supplier pricing....

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#5 2019-12-02 20:27:24

louis
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From: UK
Registered: 2008-03-24
Posts: 5,176

Re: Power to gas - the next step

The conversion loss is meaningless in a money-based economy.  What the market pricing signals (or will in the near future) is that it is  cheaper to have intermittent wind and solar and then use surplus energy you don't need for the grid to manufacture methane (that you can then use to provide baseload0. Doesn't matter if there's a conversion loss - potentially it will be cheaper than actually extracting methane out of the ground...that's always going to be a process with a sizeable price tag attached (and that price tag reflects the energy used to get the gas out of the ground, pump it along pipelines, freeze it, put it on ships and then store it before use). Another way of looking at it is to say that energy conversion losses in methane manufacture have to be set against energy usage to extract methane from the ground and transport it to where it is required (remember - methane manufacture can take place pretty much anywhere in the world ). That energy usage is reflected in price.


SpaceNut wrote:

The energy is being paid for by those that connect to the grid as supplies as they gamble on that surplus... its the reseller thats over charging for its use....
Changing that game is the solar company which is not selling it all to the gamblers as they are saving it for later but its at a hugh conversion loss...

Last edited by louis (2019-12-02 20:39:42)


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#6 2019-12-03 04:59:01

louis
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From: UK
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Posts: 5,176

Re: Power to gas - the next step

Seems like a number of economists think (renewable) power to gas may already be financially viable for small to medium term projects and could become viable for large projects by 2030.

https://www.pv-magazine.com/2019/02/28/ … dy-viable/

Seems to me this is only going one way: green energy plus P2G storage = a complete energy solution that will actually be cheaper than fossil fuels and nuclear. We're not quite there yet but everything - continuing reductions in the price of wind, solar, chemical batteries and P2G storage all point in the same direction.


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#7 2019-12-03 08:15:49

tahanson43206
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Registered: 2018-04-27
Posts: 1,332

Re: Power to gas - the next step

For Louis re #6

Please develop your ideas for this "new" industry a bit further.

I understand that the possibility of leading a multi-billion dollar corporation seems slim, for any specific individual with limited capital.  However, as Calliban's countryman Adam Smith pointed out long ago, the key to wealth accumulation is the ability to encourage productive activity by fellow humans. 

You seem to have a talent for stimulating/motivating talented people who participate in this forum to exert themselves in combat against the silly ideas you propose, and then defend against the best arguments they can offer.

Here is an opportunity to propose a really GOOD idea, and stimulate your fellows in Britain to build a corporation large enough to supply methane on a global scale.

Edit: There is opportunity in crisis.
https://www.yahoo.com/finance/news/gree … 00008.html

The renewable methane idea might be attractive to folks who are facing the consequences described in the article.

(th)

Last edited by tahanson43206 (2019-12-03 08:41:25)

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#8 2019-12-03 10:25:32

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 181

Re: Power to gas - the next step

louis wrote:

Seems like a number of economists think (renewable) power to gas may already be financially viable for small to medium term projects and could become viable for large projects by 2030.

https://www.pv-magazine.com/2019/02/28/ … dy-viable/

Seems to me this is only going one way: green energy plus P2G storage = a complete energy solution that will actually be cheaper than fossil fuels and nuclear. We're not quite there yet but everything - continuing reductions in the price of wind, solar, chemical batteries and P2G storage all point in the same direction.

Power to gas is not as simple as Louis makes it sound.  I would expect this technology to have niche solutions.

In this context, power-to-gas means using excess electrical power to electrolyse water; store the resulting hydrogen in some sort of tank at close to atmospheric pressure (i.e. a gasometer) and then burn it in a gas turbine when power is less abundant.  This is the simplest and cheapest arrangement and it avoids the need for liquefaction, compression equipment or storage in pressure vessels and the energy costs associated with all of this.

Certainly, this can be made to work.  At first sight, the capital costs involved do not appear excessive – electrolysers are common industry equipment; the hydrogen tank is a thin-walled steel tank with sliding sections, something that has been built and used since Victorian times.  Combined and open cycle gas turbines are common equipment too and these types of power plant have low capital costs, thanks to rapid build time and high power density.  So storage system capital costs look quite affordable, which no doubt leads to the low operating cost assessments from many economics 'experts'.  So where's the rub?

1.    Thermal efficiency of the whole system is about 30%.  Electrolysis ~70%; losses in storage ~a few percent; combined cycle gas turbine ~50%; electrical transitions ~90%.  The 70% losses are mostly in the form of heat.  Maybe we can make use of that heat for space heating; but that requires a lot of extra infrastructure.  The problem with poor thermal efficiency is that it requires even more primary energy production to make up for losses.  If half of all electricity is generated from storage that is 30% efficient, then the amount of wind/solar electricity needed for one unit of power roughly doubles.  You need twice as many wind turbines and solar panels – with twice the capital and operating cost.  Then you have the capital and operating costs of the CCGT and storage plant on top of that.  All of a sudden, the cost of electricity has tripled.

2.    The energy density of hydrogen gas is poor: 10.5MJ/m3 under standard conditions.  That is a bit more than a quarter of the energy density of methane.  To store enough hydrogen to power a 400MWe gas turbine plant for 24 hours, would require a storage tank 6.5million cubic metres in volume.  That is a huge piece of infrastructure that no one would want to be next door to.  Power-to-gas is a relatively inefficient way of achieving short-term energy storage.

3.    In densely populated countries, like Northern Europe and East Asia; renewable energy is already facing conflicts where it intrudes upon living space.  It would be prudent to avoid relying upon a storage system with poor cycle efficiency.  On a small scale, power-to-gas might be useful in niche applications.  In commercial buildings, waste heat could be used for space heating, with electricity sold back to the grid.  The issue here will be safely storing hydrogen gas.  In the chemical industry, hydrogen is a useful reducing agent.

No one ever cheats the second law of thermodynamics.  Randomly intermittent power is far less valuable than controllable power.  There are substantial costs involved in converting unreliable electricity into reliable electricity.

Last edited by Calliban (2019-12-03 10:29:28)


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#9 2019-12-03 10:44:11

tahanson43206
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Registered: 2018-04-27
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Re: Power to gas - the next step

SearchTerm:WindTurbineMethane
SearchTerm:MethaneWind

For Calliban re #8 ... thank you for your (to my way of thinking) helpful reply to Louis ...

For Louis re topic ... Calliban has given you a sense of what it will take for you to make methane, by concentrating on ONE input.

You'll also need to capture Carbon from CO2 in the air, and run the conversion to make methane.

Calliban has pointed out that you will need to liquefy the methane for shipment to your customers world-wide, and there will be some losses in shipment, in addition to the portion of the payload expended to operate the transportation system.

As you pointed out earlier, all of these losses can be accounted for if you can persuade your customers to pay your costs plus a (probably small) margin for the investors.

Please try to put the entire package together, to see if your optimism is justified.

One point I would like to offer to try to assist you is this:

A floating wind turbine can perform ALL the functions needed to deliver methane to pick up vehicles.

If each such turbine has a 30 year life, then your plan will require allocation of resources to refurbish the unit for another 30 years.

Some of your budget should (no doubt) be set aside for losses due to weather or human error.

Can you make all that work?

A prize of some sort surely awaits the person who can.

Edit#1: The modern age is hard at work on capabilities to insure your success.

Here is an unlikely potential ally: https://www.youtube.com/watch?v=MR9PoBAssw0

Amazon made that video in 2016, and it is now 2019.  With three years advance, the ability to collect containers of methane from floating turbine towers seems all the more feasible.  Drones for service at sea need to be a bit more robust than those intended for home delivery, but the principles of operation seem likely to be identical.  Canisters of methane would be delivered to a compression/liquefaction facility, from which the output would be collected periodically by appropriate vehicles.

Europe would seem (to me at least) a particularly attractive customer region, because of the distasteful dependence upon natural gas from certain land based providers.

Edit#2: Harnessing human creativity seems to work well in a competitive environment.

Design and manufacture of methane producing floating wind turbine systems will be an activity that lends itself to global competition, aimed at increasing efficiency at every stage.  Calliban has identified efficiencies that can be expected as a starting point, but in service of competition between turbine providers, subcontractors from around the planet will be incentivized to produce more and more efficient components.

For each round of procurement, the designs and manufactured packages would be evaluated based upon performance.

The variability of wind by location and season needs to be taken out of the comparison.

Less efficient packages can be moved to locations where wind is strongest and most consistent.

There is a permanent belt of wind around Antarctica that should be of great interest to all players.

Edit 2019/12/04: I would like to see this topic develop into a working design for a floating wind turbine able to make methane for global distribution.

The technology needed for floating wind turbines is now well advanced in 2019.  Technology for capture of CO2 from the air is coming along well.

Technology for production of Hydrogen from water is well known.  Technology for separating water from salt and other dissolved material in sea water is well known.  Technology for production of methane given inputs of Carbon and Hydrogen is well known.

Output from the system would be methane gas collected in containers at modest pressure.  The gas would be transported to regional facilities where it would be compressed and cooled for shipment to customers world wide.

(th)

Last edited by tahanson43206 (Yesterday 07:51:22)

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#10 2019-12-03 11:17:42

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 181

Re: Power to gas - the next step

Tahanson, I was talking about storing energy in non-compressed hydrogen gas stored in a gasometer.  The efficiency of that process is about 30%.

The numbers for methane look worse, mainly because of the additional energy losses involved in reducing CO2.  Looking at the link below:
https://en.wikipedia.org/wiki/Sabatier_reaction

Crunching the numbers for methane-oxygen bipropellant.  In an optimised process, one tonne of bipropellant (11GJ of energy) could be produced using 17MWh of electricity – 61.2GJ.  That is 18% efficiency.  Does that include the energy cost of liquefaction?  The link does not specify.

Distributing the methane, liquid or otherwise, would consume more energy.  If we burn the methane in an open cycle gas turbine, its efficiency is about 30%.  Closed cycle with waste heat boiler – about 50%.

Whole cycle efficiency is 5.4-9%.  Not including energy lost in capturing CO2, liquefaction and transport of methane.  That sort of inefficiency is only tolerable in small volume niche applications, where you really cannot find another source of methane.

Power-to-gas may fill some small to medium scale niche energy storage applications if it combines a simple non-pressurised hydrogen storage system with a gas turbine, with waste heat recovery.  My own hunch is that it would be more cost effective to install grid operated storage heaters, than to mess around with small systems involving electrolysers, gas storage tanks and gas turbines.  Most of the energy is lost as heat anyway.

Last edited by Calliban (2019-12-03 11:25:38)


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#11 2019-12-03 11:24:42

tahanson43206
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Registered: 2018-04-27
Posts: 1,332

Re: Power to gas - the next step

For Calliban re #10 and topic in general ...

My bet is that the world will become so desperate for a solution in the next 10 years that if only 1% of the energy from wind passing by a turbine is delivered to customers, whatever the cost might be, it will be accepted as the price of avoiding the consequences of doing business as usual.

You've indicated a potential efficiency of 5% in your post.  That would be quite amazing if actually achieved.

100% of the wind passing the proposed turbine locations is being wasted at present.

Delivery of 5% of that energy to a village in Alaska (as just one example) would be a remarkable achievement.

(th)

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#12 2019-12-03 14:47:41

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 181

Re: Power to gas - the next step

tahanson43206 wrote:

For Calliban re #10 and topic in general ...

My bet is that the world will become so desperate for a solution in the next 10 years that if only 1% of the energy from wind passing by a turbine is delivered to customers, whatever the cost might be, it will be accepted as the price of avoiding the consequences of doing business as usual.

You've indicated a potential efficiency of 5% in your post.  That would be quite amazing if actually achieved.

100% of the wind passing the proposed turbine locations is being wasted at present.

Delivery of 5% of that energy to a village in Alaska (as just one example) would be a remarkable achievement.

(th)

Even marginal fossil fuel resources, like US tight oil (which is drowning in debt) still offer a positive net energy return.  It is very unlikely that synthetic methane ever could, because of the huge losses involved.  Even non-compressed electrolytic hydrogen would seriously diminish the already mediocre net energy return from wind and solar power plants.

If I were to contemplate what a renewable energy future might look like, I would be looking at options that minimized the amount of storage needed and minimized the number of energy transitions.  Storage of electricity to be converted back into electricity should be avoided.  Energy storage should focus of end-uses.

Taking the UK as an example, some 65% of energy end use is in the form of heat.  Space heating, hot water, cooking and industrial heat.  Of the remaining third, some proportion of that is refrigeration, which is another form of heat.  Heat is relatively cheap to store and days worth of domestic heat could be stored in a hot water tank, a couple of cubic metres in volume.  If this portion of demand could be controlled, the remaining 30% of energy demand would be much more reliable.

Gridwatch provides historic data for UK electricity generation, including renewables (see below).
https://gridwatch.co.uk/renewables

Take a look at last month's renewable power generation and last years.  The effective installed capacity is about 15GWe.  Notice that whilst there is a lot of variability between 5 and 15GWe, combined wind a solar output only occasionally drops beneath 5GWe.  If we could power the heat consuming parts of the economy using grid-controlled storage heaters, there would appear to be little need for additional energy storage.  We could fill in the occasional lulls in renewable energy using open cycle gas turbines burning biogas.  Very short-term imbalances could be levelled using small amounts of batteries and pumped storage, with limited storage capacity, but high discharge rate.  This would appear to me to be the cheapest all round solution.  Whether it could ever be as affordable as fossil fuels in their heyday is less likely.

Last edited by Calliban (2019-12-03 15:00:35)


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#13 2019-12-03 14:54:12

louis
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From: UK
Registered: 2008-03-24
Posts: 5,176

Re: Power to gas - the next step

Calliban,

My preference would be for production of methane, not hydrogen, with the manufacture being powered by electricity that would otherwise be wasted (earthed).

1. The energy inefficiency is irrelevant. The energy is going to waste anyway. So, you are simply making use of energy that otherwise will be wasted and therefore has a zero or close to zero cost.  Yes, maybe you have to produce 10 units of energy to get your 3 units of output but the 10 units cost virtually zero while the 3 units have a high value as baseload energy.

2. I favour methane as the end product (partly because storage is less of an issue), but yes if you opted for hydrogen of course, as with nuclear power, you would choose an isolated location without a lot of residential property close by.

3. It's true that there are issues with residents' resistance to some forms of renewable energy - no one is going to welcome a wind turbine or solar farm close to their home. One option that is being actively pursued is floating wind turbines - an option for most countries in Western Europe.  We might see floating solar as well. But the development of ultra thin PV will provide many opportunities for rooftop solar.

Gas is controllable power.

A renewable energy system would have dependable levels of baseload power from energy-from-waste, geothermal and biofuels. On an average day that might get you up to 10%.  Wind, solar, hydro, tidal and wave would usually produce the remaining 90%. On the days when there is more electricity produced than is required by demand, the electricity would be used to produce methane.  On the days when green energy can't meet demand, you would use methane to generate electricity and also increase supply from hydro.

Once wind and solar are producing electricity more cheaply than fossil fuels and nuclear, this system makes perfect sense because it allows you to increase the proportion of green energy, overcoming the problem of intermittency.



Calliban wrote:
louis wrote:

Seems like a number of economists think (renewable) power to gas may already be financially viable for small to medium term projects and could become viable for large projects by 2030.

https://www.pv-magazine.com/2019/02/28/ … dy-viable/

Seems to me this is only going one way: green energy plus P2G storage = a complete energy solution that will actually be cheaper than fossil fuels and nuclear. We're not quite there yet but everything - continuing reductions in the price of wind, solar, chemical batteries and P2G storage all point in the same direction.

Power to gas is not as simple as Louis makes it sound.  I would expect this technology to have niche solutions.

In this context, power-to-gas means using excess electrical power to electrolyse water; store the resulting hydrogen in some sort of tank at close to atmospheric pressure (i.e. a gasometer) and then burn it in a gas turbine when power is less abundant.  This is the simplest and cheapest arrangement and it avoids the need for liquefaction, compression equipment or storage in pressure vessels and the energy costs associated with all of this.

Certainly, this can be made to work.  At first sight, the capital costs involved do not appear excessive – electrolysers are common industry equipment; the hydrogen tank is a thin-walled steel tank with sliding sections, something that has been built and used since Victorian times.  Combined and open cycle gas turbines are common equipment too and these types of power plant have low capital costs, thanks to rapid build time and high power density.  So storage system capital costs look quite affordable, which no doubt leads to the low operating cost assessments from many economics 'experts'.  So where's the rub?

1.    Thermal efficiency of the whole system is about 30%.  Electrolysis ~70%; losses in storage ~a few percent; combined cycle gas turbine ~50%; electrical transitions ~90%.  The 70% losses are mostly in the form of heat.  Maybe we can make use of that heat for space heating; but that requires a lot of extra infrastructure.  The problem with poor thermal efficiency is that it requires even more primary energy production to make up for losses.  If half of all electricity is generated from storage that is 30% efficient, then the amount of wind/solar electricity needed for one unit of power roughly doubles.  You need twice as many wind turbines and solar panels – with twice the capital and operating cost.  Then you have the capital and operating costs of the CCGT and storage plant on top of that.  All of a sudden, the cost of electricity has tripled.

2.    The energy density of hydrogen gas is poor: 10.5MJ/m3 under standard conditions.  That is a bit more than a quarter of the energy density of methane.  To store enough hydrogen to power a 400MWe gas turbine plant for 24 hours, would require a storage tank 6.5million cubic metres in volume.  That is a huge piece of infrastructure that no one would want to be next door to.  Power-to-gas is a relatively inefficient way of achieving short-term energy storage.

3.    In densely populated countries, like Northern Europe and East Asia; renewable energy is already facing conflicts where it intrudes upon living space.  It would be prudent to avoid relying upon a storage system with poor cycle efficiency.  On a small scale, power-to-gas might be useful in niche applications.  In commercial buildings, waste heat could be used for space heating, with electricity sold back to the grid.  The issue here will be safely storing hydrogen gas.  In the chemical industry, hydrogen is a useful reducing agent.

No one ever cheats the second law of thermodynamics.  Randomly intermittent power is far less valuable than controllable power.  There are substantial costs involved in converting unreliable electricity into reliable electricity.


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#14 2019-12-03 15:35:21

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,176

Re: Power to gas - the next step

Most heat in the UK is produced by gas - fully controllable.

The EROI is very misleading. Take nuclear power for instance - it has by far the best EROI...so, you might ask, why is it so expensive? Well because a lot of the energy input is disguised as human labour input. But humans need to be paid, and they are effectively paid in energy (wages buy energy use to produce food and consumer products). A wind turbine's EROI may look less impressive on paper, but it is generally speaking a pretty automated way to produce energy. Once it's up and running it requires few humans to keep it going.


Calliban wrote:
tahanson43206 wrote:

For Calliban re #10 and topic in general ...

My bet is that the world will become so desperate for a solution in the next 10 years that if only 1% of the energy from wind passing by a turbine is delivered to customers, whatever the cost might be, it will be accepted as the price of avoiding the consequences of doing business as usual.

You've indicated a potential efficiency of 5% in your post.  That would be quite amazing if actually achieved.

100% of the wind passing the proposed turbine locations is being wasted at present.

Delivery of 5% of that energy to a village in Alaska (as just one example) would be a remarkable achievement.

(th)

Even marginal fossil fuel resources, like US tight oil (which is drowning in debt) still offer a positive net energy return.  It is very unlikely that synthetic methane ever could, because of the huge losses involved.  Even non-compressed electrolytic hydrogen would seriously diminish the already mediocre net energy return from wind and solar power plants.

If I were to contemplate what a renewable energy future might look like, I would be looking at options that minimized the amount of storage needed and minimized the number of energy transitions.  Storage of electricity to be converted back into electricity should be avoided.  Energy storage should focus of end-uses.

Taking the UK as an example, some 65% of energy end use is in the form of heat.  Space heating, hot water, cooking and industrial heat.  Of the remaining third, some proportion of that is refrigeration, which is another form of heat.  Heat is relatively cheap to store and days worth of domestic heat could be stored in a hot water tank, a couple of cubic metres in volume.  If this portion of demand could be controlled, the remaining 30% of energy demand would be much more reliable.

Gridwatch provides historic data for UK electricity generation, including renewables (see below).
https://gridwatch.co.uk/renewables

Take a look at last month's renewable power generation and last years.  The effective installed capacity is about 15GWe.  Notice that whilst there is a lot of variability between 5 and 15GWe, combined wind a solar output only occasionally drops beneath 5GWe.  If we could power the heat consuming parts of the economy using grid-controlled storage heaters, there would appear to be little need for additional energy storage.  We could fill in the occasional lulls in renewable energy using open cycle gas turbines burning biogas.  Very short-term imbalances could be levelled using small amounts of batteries and pumped storage, with limited storage capacity, but high discharge rate.  This would appear to me to be the cheapest all round solution.  Whether it could ever be as affordable as fossil fuels in their heyday is less likely.


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#15 2019-12-03 16:19:09

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 181

Re: Power to gas - the next step

louis wrote:

Most heat in the UK is produced by gas - fully controllable.

The EROI is very misleading. Take nuclear power for instance - it has by far the best EROI...so, you might ask, why is it so expensive? Well because a lot of the energy input is disguised as human labour input. But humans need to be paid, and they are effectively paid in energy (wages buy energy use to produce food and consumer products). A wind turbine's EROI may look less impressive on paper, but it is generally speaking a pretty automated way to produce energy. Once it's up and running it requires few humans to keep it going.

Nuclear power is not expensive.  It is one of the cheapest baseload electricity sources.  Basic operating costs are low.  Even with enormous regulatory burden, it still outperforms most other energy sources.  A good question would be why it was so easy to build reactors in the 1970s, but so difficult now.  There is no practical reason why.

https://www.greentechmedia.com/articles … chnologies

Last edited by Calliban (2019-12-03 16:32:44)


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#16 2019-12-03 16:38:24

Terraformer
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From: Lancashire
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Posts: 3,145
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Re: Power to gas - the next step

If we could power the heat consuming parts of the economy using grid-controlled storage heaters, there would appear to be little need for additional energy storage.  We could fill in the occasional lulls in renewable energy using open cycle gas turbines burning biogas.  Very short-term imbalances could be levelled using small amounts of batteries and pumped storage, with limited storage capacity, but high discharge rate.  This would appear to me to be the cheapest all round solution.  Whether it could ever be as affordable as fossil fuels in their heyday is less likely.

If you have a large chunk of rock in your house, you could heat or cool it with a heat pump whenever you have energy. Stored heat (or 'cold', like ice in refrigerators), combined with biofuels for meeting the lulls, are something I've thought would be the way to go for a while. If solar works 80% of the time, then it's a lot easier to use biofuel standby plants.


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#17 2019-12-03 17:19:29

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 181

Re: Power to gas - the next step

Wind power is heavy on steel and concrete inputs.  Inputs that are dependent on fossil fuels at present.

https://pdfs.semanticscholar.org/519e/a … 6c6658.pdf

A MW of wind power requires about 10 times more steel than a MW from a pressurised water reactor.  And that is without backup or storage.  Much of that steel comes from China, and is produced using coal.  It is processed using electricity that is heavily coal based.

A renewable electricity system would be heavy on material inputs.  Metal ores must be mined using diesel; smelted using coal, remelted and cast using electricity; transported using diesel and then assembled using diesel powered ships or trucks.

None of this is environmentally friendly and when fossil fuels hit the rocks, it won't be cheap.  Green energy is more about ideology than it is about the environment.  Environmentalists are interested in practical environmental protection.  Greens are interested in ideological purity and gay rights.

Last edited by Calliban (2019-12-03 17:21:41)


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#18 2019-12-03 19:41:08

louis
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From: UK
Registered: 2008-03-24
Posts: 5,176

Re: Power to gas - the next step

Depends what you mean by "at present".

Yes, turbines use a lot of steel. But there's no reason to think the towers can't be reused for the next generation of turbine.

Currently coal is required to make steel. Whether that remains the case is to be seen.

Vestas claim that a modern wind turbine produces about 25-50 times the amount of energy that goes into its manufacture.

A lot of wind energy, especially on land, is already far cheaper than coal in terms of electricity generation.

And take a look at the cost graphs - everything is going in one direction (down) and at a fast rate. Nuclear power and fossil fuels are remaining at the same level or slightly below.

Don't know what gay rights have got to do with green energy!


Calliban wrote:

Wind power is heavy on steel and concrete inputs.  Inputs that are dependent on fossil fuels at present.

https://pdfs.semanticscholar.org/519e/a … 6c6658.pdf

A MW of wind power requires about 10 times more steel than a MW from a pressurised water reactor.  And that is without backup or storage.  Much of that steel comes from China, and is produced using coal.  It is processed using electricity that is heavily coal based.

A renewable electricity system would be heavy on material inputs.  Metal ores must be mined using diesel; smelted using coal, remelted and cast using electricity; transported using diesel and then assembled using diesel powered ships or trucks.

None of this is environmentally friendly and when fossil fuels hit the rocks, it won't be cheap.  Green energy is more about ideology than it is about the environment.  Environmentalists are interested in practical environmental protection.  Greens are interested in ideological purity and gay rights.


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#19 2019-12-03 19:46:13

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 16,726

Re: Power to gas - the next step

Net metering to the gird is done with supply contracts for the selling of the power created. Any energy not under a specific contract is still going into the grid via the net metering connection so no excess is available. Its just not covered under a single contract purchase. The only excess is once the contract for sales are met and you disconnect the net metering from the grid....

So now you are making energy that has no sale value but its at a lose of income based on not selling it for what you would normally get. Thats the investment in kwhrs of cash into the fuel creation storage to be used. So adding up all of the kwhrs to do each function in the process is your cost to make the fuel quantity. Where you either are below the sales of normal fuels or not. As the cost of the power is what the value of the fuel is if you had sold the energy directly.

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#20 Yesterday 08:06:15

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,332

Re: Power to gas - the next step

For Calliban ...

Not long ago, in this topic or another one with a similar theme, you provided an example of clever design from the historical record.  I recall that the method was to compress gas (in the example it was air) in a flow of water over a drop of (about) 100 meters.  My recollection is that you said that the process was able to perform compression and cooling simultaneously in a very efficient way.  To my way of thinking the cooling would be accomplished by heating the water, but in the context of a mining operation drawing water from a natural stream, the heating of the water would not be consequential (or perhaps even noticeable).

At the time of your post, I did not think the method could be employed in the modern age for a practical application.  However, Louis' initiative here to try explore the potential of using wind power to make methane inspired (me at least) to try to think of a way to reduce the complexity of a methane compression operation at sea.  Do you know if the 1700's compression method could be applied in the present age, by pulling water down a pipe?

What I'm wondering is whether a water column in the ocean could perform practical compression of methane gas.  As I am imagining the system, a pump at the bottom of the water column would pull water from the column, while compressed methane bubbles would be drawn off to a second pipe where pressure would be maintained.  The compressed gas would then be drawn off at the surface for further processing.

My (admittedly limited) understanding is that natural gas is currently liquefied by mechanical systems (pumps) and that waste heat is passed to the atmosphere via radiators.

In the hypothetical vertical water column, the heat would be passed to the ocean, which has its own consequences, of course.

(th)

Last edited by tahanson43206 (Yesterday 08:06:34)

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#21 Yesterday 09:29:20

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 181

Re: Power to gas - the next step

41 Inconvenient Truths on the "New Energy Economy".  Why it will be very difficult and expensive to replace fossil fuel energy with renewable energy.

https://fee.org/articles/41-inconvenien … qus_thread

Some personal favourites:

2. The small two-percentage-point decline in the hydrocarbon share of world energy use entailed over $2 trillion in cumulative global spending on alternatives over that period; solar and wind today supply less than two percent of the global energy.

4. A 100x growth in the number of electric vehicles to 400 million on the roads by 2040 would displace five percent of global oil demand.

5. Renewable energy would have to expand 90-fold to replace global hydrocarbons in two decades. It took a half-century for global petroleum production to expand “only” ten-fold.

6. Replacing U.S. hydrocarbon-based electric generation over the next 30 years would require a construction program building out the grid at a rate 14-fold greater than any time in history.

7. Eliminating hydrocarbons to make U.S. electricity (impossible soon, infeasible for decades) would leave untouched 70 percent of U.S. hydrocarbons use—America uses 16 percent of world energy.

12. For security and reliability, an average of two months of national demand for hydrocarbons are in storage at any time. Today, barely two hours of national electricity demand can be stored in all utility-scale batteries plus all batteries in one million electric cars in America.

13. Batteries produced annually by the Tesla Gigafactory (world’s biggest battery factory) can store three minutes worth of annual U.S. electric demand.

14. To make enough batteries to store two day's worth of U.S. electricity demand would require 1,000 years of production by the Gigafactory (world’s biggest battery factory).

17. Over a 30-year period, $1 million worth of utility-scale solar or wind produces 40 million and 55 million kWh respectively: $1 million worth of shale well produces enough natural gas to generate 300 million kWh over 30 years.

18. It costs about the same to build one shale well or two wind turbines: the latter, combined, produces 0.7 barrels of oil (equivalent energy) per hour, the shale rig averages 10 barrels of oil per hour.

19. It costs less than $0.50 to store a barrel of oil, or its equivalent in natural gas, but it costs $200 to store the equivalent energy of a barrel of oil in batteries.

Here is one of my own: To produce a single unit of baseload power supply using wind and solar energy, requires roughly twenty times as much invested energy and materials, compared to a nuclear power plant of the same power.  This investment would need to be carried out in a world where fossil fuel energy is depleting and it would need to be repeated every twenty years.

In other words, to replace US hydrocarbon based electricity generation over 30 years, would require that we invest 280 times as much energy in electricity infrastructure than at any point in history.  Building renewable electricity infrastructure at the required rate would balloon US energy requirements.

By way of contrast, the French were able to replace most of their fossil fuel electricity generating infrastructure with pressurised water reactors in about two decades.  They were able to do that at an affordable cost, because of the much greater power density of nuclear reactors compared to renewable energy sources.  It is about one twentieth of the building work.

Last edited by Calliban (Yesterday 09:39:37)


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#22 Yesterday 09:59:23

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 181

Re: Power to gas - the next step

tahanson43206 wrote:

For Calliban ...

Not long ago, in this topic or another one with a similar theme, you provided an example of clever design from the historical record.  I recall that the method was to compress gas (in the example it was air) in a flow of water over a drop of (about) 100 meters.  My recollection is that you said that the process was able to perform compression and cooling simultaneously in a very efficient way.  To my way of thinking the cooling would be accomplished by heating the water, but in the context of a mining operation drawing water from a natural stream, the heating of the water would not be consequential (or perhaps even noticeable).

At the time of your post, I did not think the method could be employed in the modern age for a practical application.  However, Louis' initiative here to try explore the potential of using wind power to make methane inspired (me at least) to try to think of a way to reduce the complexity of a methane compression operation at sea.  Do you know if the 1700's compression method could be applied in the present age, by pulling water down a pipe?

What I'm wondering is whether a water column in the ocean could perform practical compression of methane gas.  As I am imagining the system, a pump at the bottom of the water column would pull water from the column, while compressed methane bubbles would be drawn off to a second pipe where pressure would be maintained.  The compressed gas would then be drawn off at the surface for further processing.

My (admittedly limited) understanding is that natural gas is currently liquefied by mechanical systems (pumps) and that waste heat is passed to the atmosphere via radiators.

In the hypothetical vertical water column, the heat would be passed to the ocean, which has its own consequences, of course.

(th)

It is possible in principle to build a trompe in the sea.  If it were to be done that way, it would make sense to store the methane (or other gas) at depth, in flexible membranes that use the hydrostatic pressure of the sea to keep the gas under pressure and compression.

Because the trompe continuously cools gas bubbles during compression, there is very little energy loss.  However, some quantity of gas does dissolve into the water and this is released from the return loop.  But the compressor is about 80% efficiency for air.

Kris DeDecker discusses the trompe at some length.
https://www.lowtechmagazine.com/2018/05 … onomy.html

The main problems with the trompe are (1) Its huge size for the amount of output it produces; (2) The fact that in most hydropower situations, electricity is a more useful product than compressed air.  Trompes have received a revival of interest because of the potential to support CAES.


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#23 Yesterday 10:17:43

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,332

Re: Power to gas - the next step

For Calliban re #22

Thank you for the (properly) measured endorsement of the principle. 

Louis .... since you are the originator of this topic, and have the most to gain from its success, please apply your financial acumen to what we (collectively as forum contributors) have put on the board so far.

The question at hand is whether technology identified so far can be assembled to deliver "green" methane to a global customer base (a) and (b) if the cost of the product would be competitive with alternatives given a customer who refuses to use fossil fuels.

Part of your expense (of course) will be education of the potential buyer that the methane you will be offering is indeed "new" methane, not drawn from terrestrial reserves.

As you have pointed out on numerous occasions, a system once built and proven can be reproduced at steadily decreasing cost, so that income earned from the product moves ever so slowly but inevitably toward repayment of the initial investment.

Given the size of the potential wind field around Antarctica, the amount of methane producible by this mechanism should be sufficient to meet global needs.

***

For Calliban ... I like your suggestion of keeping the methane output in bladders at the bottom of the down-pipe, until it is drawn off for distribution.

There are a great number of trades at work in this situation.  There may be a sweet spot where the optimum (least cost) solution becomes apparent.

Since all the energy to drive this system was known to sailors 500 years ago (if not 5000), it is apparent that the available energy supply is free to those who have the ability to harness it as they did for transportation.

(th)

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#24 Yesterday 10:31:03

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,332

Re: Power to gas - the next step

For Louis re topic ...

By happy circumstance, here is a possible customer community for your "green" methane.

It is also a coincidence that you are in Britain, and Britain is looking for a way to become relevant in the world which is as competitive as at present.

https://www.yahoo.com/finance/news/wait … 07571.html

(Bloomberg Opinion) -- Next week, the European Union’s leaders will commit to cutting net greenhouse gas emissions to zero by 2050. This historic pledge will require the continent to radically overhaul its entire economy, including a revolution in the production of steel, cement and chemicals — whose carbon emissions are particularly difficult to abate.

Edit#1: Can someone (please) verity my expectation that methane can provide all the temperatures needed for production of these commodities?

In the case of steel, production of electric arcs is an alternative to direct application of combustion of methane.

(th)

Last edited by tahanson43206 (Yesterday 10:34:04)

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#25 Yesterday 11:16:53

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 181

Re: Power to gas - the next step

tahanson43206 wrote:

For Louis re topic ...

Edit#1: Can someone (please) verity my expectation that methane can provide all the temperatures needed for production of these commodities?

In the case of steel, production of electric arcs is an alternative to direct application of combustion of methane.

(th)

Methane is basically natural gas.  Flame temperature in air is 1950C.

https://www.engineeringtoolbox.com/flam … d_422.html

To produce Portland cement, temperatures of 1450C are needed.  So yes it would work and indeed most cement factories in the western world already use natural gas for heat production.

https://en.wikipedia.org/wiki/Cement#Portland_cement

But I go back to my original point.  You start with electricity (a high grade energy source) and lose over 80% of its useful energy producing a fuel that will be used to generate heat, which could have been produced using the electricity to begin with.

Considering that it takes an order of magnitude more refined materials to produce a unit of power with wind energy (compared to fossil and nuclear) is it really sensible to use electricity in this way?

Purely from an energy cost point of view, if you start with electricity costing $0.1/kWh; the methane will cost $0.5/kWh.  Capital costs will go on top of that.  Hydrogen would be much cheaper.  Electricity cheaper still.

Natural gas costs $0.01-$0.14/kWh depending on location.
https://www.globalpetrolprices.com/natural_gas_prices/

Even in a renewable energy context, you would need to compete with biogas.

Last edited by Calliban (Yesterday 11:24:00)


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