Is there an alternate fuel that de-emphasizes carbon?

[DEvens]

TL;DR Summary

Is there an alternate fuel that de-emphasizes carbon?

Is there a potential fuel, for some kind of engine, not necessarily similar to existing car or diesel engines, that does not have carbon in it? That is, that you might manufacture from water and air without having to concentrate the carbon dioxide somehow. And that's liquid at ordinary temperatures and pressures one might find walking around in an ordinary town.

Yes, I am aware of the Dunning-Kruger effect. Talk to me like an ignorant 9 year old if it seems appropriate. My last chemistry class was in first year undergrad, and that was [mumble] years ago. And I got a crappy mark.

But imagine: A windmill generates this stuff. Intermittently possibly. As its inputs it needs air and water. The water might well be from rain or a nearby well. Supposing it was a liquid at normal temperature and pressure. It could collect in a nice holding tank. The tank would not need to be pressurized or cryogenically cooled. Then once a month a tanker truck could come collect it for use in car engines. Using it in engines would then return it to water and air.

It would be especially interesting if it was useful in aircraft engines. Again, not necessarily of the existing design engine.

Is there any such chemical?

 

[DrClaude]

Why not add non-toxic and non-polluting, while you're at it.

If there was such a chemical, you can be sure someone would be getting fifty rich right now by producing it.

And why shy away from carbon compounds? The problem wrt climate change is fossil fuels. If you could make fuel using atmospheric CO₂, why not? This is basically the point of trying to make biofuels.

 

[russ_watters]

That's a tough list of constraints, but you forgot to include "inexpensive"!

I think if such a chemical existed, it would already be obvious and we'd already be using it. You listed air and water as the sources, which pretty much limits the constituents to oxygen, hydrogen and nitrogen, and their chemistry is already very well known. And plain hydrogen is the obvious choice from that list.

Personally, I don't see the gas vs cryogenic liquid thing to be that big of a deal. It even has its benefits, like providing free cooling.

 

[TeethWhitener]

Nitric oxide can be produced from oxygen and nitrogen in the Birkeland Eyde process
https://en.wikipedia.org/wiki/Birkeland–Eyde_process
NO can then be reacted with oxygen to form NO₂ which is fairly easy to store (boils at around 20°C at atmospheric pressure). NO₂ has a positive heat of formation and can therefore be decomposed to elemental nitrogen and oxygen to release energy.

Of some relevance, this process is extraordinarily inefficient. Also, NO₂ is basically smog in a bottle.

 

[DEvens]

And why shy away from carbon compounds? The problem wrt climate change is fossil fuels. If you could make fuel using atmospheric CO₂, why not? This is basically the point of trying to make biofuels.

The problem with carbon in fuel made this way is getting the carbon. Collecting a component that is at the low levels CO2 is in the atmosphere requires some difficult processes. Since it's round-about 400 ppm, it means to get 1 kg of fuel you need to pump something round about 2000 kg of air. Depending on the efficiency that could be a lot more. So it's an energy intensive process. For example, plants fix sunlight energy at something in the range of a few percent, 1% to 5% kind of thing. A non-trivial portion of the challenge is getting the CO2.

Solar collectors to replace fossil fuel seems like it isn't going to fly. Someplace on the net I found a guy estimating how wide a solar collector would have to be to power a highway. The idea was, if you had a 4-lane highway, standard "dual carriage way" for British folk, or an ordinary "freeway" for the USA folk, how wide would the strip of solar collector have to be to power the cars on that highway? His estimate was 1 km. That seems like a problem. People already resent the area and expense of highways.

If there was a useful chemical that was nitrogen, oxygen, and hydrogen, it would be a lot easier to produce because the feeder chemicals are all easy to get. Stand outside and you can get lots of oxygen and nitrogen. Dig a hole in many places and you can get water for the hydrogen.

But it seems I'm dreaming in naive.

 

[TeethWhitener]

to get 1 kg of fuel you need to pump something round about 2000 kg of air

Capturing carbon from the air is not necessarily the worst idea economically. It is free, after all.

Air has a density of about 1 kg/m³. If you set up a 1 m² "sail" that can allow air to pass and capture CO₂, then a constant breeze of 1 m/s (about 2.2 mph) will pass 2000 kg of air through your sail in a little over 30 minutes. Of course, efficiency is a factor, but we're getting quite good at making CO₂ sorbents in the form of MOFs and COFs.

 

[DEvens]

That's a tough list of constraints, but you forgot to include "inexpensive"!

I think if such a chemical existed, it would already be obvious and we'd already be using it. You listed air and water as the sources, which pretty much limits the constituents to oxygen, hydrogen and nitrogen, and their chemistry is already very well known. And plain hydrogen is the obvious choice from that list.

Personally, I don't see the gas vs cryogenic liquid thing to be that big of a deal. It even has its benefits, like providing free cooling.

Indeed. People suggest hydrogen as fuel. Then I look at how they treat propane. And I project hydrogen being stored in huge cryogenic or high pressure tanks at gas stations across every city. And I worry quite a bit.

https://www.cbc.ca/news/canada/toronto/sunrise-propane-blast-spark-still-a-mystery-1.874561
Considering the casual way people treat fueling their vehicle, it seems kind of a gnarly idea that we would have millions of people bumping around with a chemical that has an invisible flame and explodes in an alarmingly wide range of concentrations and burns at an even wider range.

Maybe it can be done. Maybe it can be done with a death and injury rate similar to the current infrastructure. I have not carefully studied the question. It would be so much easier handling a room-temperature liquid.

 

[TeethWhitener]

It would be so much easier handling a room-temperature liquid.

I'm not so sure about that.

One straightforward possibility only using N and H is the decomposition of hydrazine. It's not fun to handle. Also, there's the reaction of hydrazine with nitric acid or nitrogen dioxide. Again, none are fun to handle. Also these reactions are hypergolic. You might recognize the various combinations as rocket fuels.

The nice thing about carbon fuels is that they are pretty darn stable (high kinetic activation barrier) but they release a LOT of energy when they're burned. This combination is going to be hard to come by with any other abundant materials.

 

[TeethWhitener]

Considering the casual way people treat fueling their vehicle, it seems kind of a gnarly idea that we would have millions of people bumping around with a chemical that has an invisible flame and explodes in an alarmingly wide range of concentrations and burns at an even wider range.

This statement is almost necessarily true for any system that stores enough energy to move a few tons of material several hundred miles.

 

[Ygggdrasil]

Summary: Is there an alternate fuel that de-emphasizes carbon?

Is there a potential fuel, for some kind of engine, not necessarily similar to existing car or diesel engines, that does not have carbon in it? That is, that you might manufacture from water and air without having to concentrate the carbon dioxide somehow. And that's liquid at ordinary temperatures and pressures one might find walking around in an ordinary town.

You seem to set out three specific criteria for your alternative fuel, namely:

1. Carbon-free
2. Manufactured from water and air without the need to concentrate carbon dioxide.
3. Liquid at STP

Others in the thread have proposed many other good criteria to consider (e.g. cost), but let's examine some commonly proposed alternative fuels based on these criteria:

Hydrogen:

1. On the surface, hydrogen gas (H₂) looks to be carbon free, but see below for a discussion how it really is not.
2. Most hydrogen is produced from steam reformation of methane (natural gas), which produces carbon dioxide as a byproduct. Hydrogen production could theoretically fit your criteria if produced by electrolysis using carbon-free electricity source (e.g. nuclear, hydroelectric, wind, solar, geothermal), but most of the US electricity grid remains dependent on fossil fuels (primarily natural gas and coal).
3. Hydrogen fails this criteria (and is probably the reason you instituted criteria #3).

For a good discussion of some of the problems with hydrogen fuels, see: https://www.technologyreview.com/s/402584/hype-about-hydrogen/

Biofuels (e.g. ethanol):

1. Although biofuels are carbon-based fuels, they are considered renewable and carbon-neutral because CO₂ is sequestered from the atmosphere during their production. So, while burning these fuels releases CO₂, this is just returning CO₂ to the atmosphere that had previously been removed. Of course, one cannot make a perpetual motion machine from sequestering CO₂ in plants, burning the fuel to produce energy, and repeating the cycle. There are costs associated with converting plant matter to fuels, including monetary costs, environmental costs (e.g. carbon emissions associated with farming and fertilizer production), and opportunity costs (biofuel production, especially from food crops like corn, is fairly land intensive). Some of these costs would be much less if fuels were not produced from food crops like corn, for example, by converting cellulose to ethanol or engineering algae to produce biofuels.
2. Plants and other photosynthetic organisms are remarkable in that they can manufacture fuels from air and water and sequester carbon dioxide without the need to first concentrate the carbon dioxide. This seems to fit criteria #2 well.
3. Most biofuels would also fit this criteria.

The main problem with biofuels come from the manufacture issues listed in point #1 (in particular, monetrary, environmental and opportunity costs associated with the production of corn ethanol). Cellulosic ethanol or other biotechnological approaches could potentially meet all criteria, but cost efficient technologies have yet to be invented and demonstrated.

Ammonia:

1. Ammonia (NH₃) is a molecule that does not contain carbon, but that does not mean its production is carbon-free.
2. In theory, this could happen. However, ammonia is currently produced from the Haber-Bosch process, which uses methane as a source of the hydrogen. Researchers are developing carbon-free methods of ammonia production which would produce ammonia from water and air via electrochemical methods, but true carbon-free production would require a carbon-free electric grid.
3. Ammonia is a liquid at STP Although ammonia is not a liquid at STP, it would be much easier and safer to store and transport than something like hydrogen.

This idea has been discussed on physics forum previously: https://www.physicsforums.com/threads/an-ammonia-economy-for-energy-transport-and-storage.951445/
It shares many of the problems associated with hydrogen fuel (e.g. requirement for a carbon-free electrical grid) and the techology is still in the early stages of development, so it has not yet been demonstrated to be cost effective or practical.

Electric vehicles:

1. Electricity can theoretically be carbon free if the electric grid is carbon free. In reality, electric vehicles today are powered primarily by electricity produced from natural gas and coal. There are still environmental benefits to EVs, however, as burning fossil fuels in a power plant to generate electricity to power a car is overall more efficient and produce fewer emissions than burning gasoline in a small car engine.
2. As with most of the other technologies discussed, carbon-free/carbon-neutral production of electricity is a prerequisite for EVs to be carbon-free.
3. This fits this criteria well, and given the extensive pre-existing electric grid in the US, requires minimal infrastructural change to implement wider adoption.

EVs are the most commercially viable as demonstrated by the robust market for EVs and gas-electric hybrid vehicles and are likely the way forward in the near and perhaps far future. Deployment of EV technology does not require major infrastructural changes, and as the grid becomes more green, so do EVs.

As you can see, many of the solutions above have as a pre-requisite the development of green, carbon-free/carbon-neutral sources of electricity, so it seems like most of our efforts should be focused there rather than the more challenging problem of producing green carbon-free energy that is also compact and portable. In fact, given that coal power plants are much more harmful to the environment and human health than gas-powered cars, one could make a strong argument that the best use of carbon-free electricity production in the short-medium term would be displacement of coal power rather than production of alternative fuels.

 

[TeethWhitener]

Ammonia is a liquid at STP and would be much easier and safer to store and transport than something like hydrogen.

Ammonia is certainly easier to store than hydrogen, but it is not a liquid at STP. It liquefies at -33°C and 1 atm, or alternately at around 8 atm and room temperature.

 

[DEvens]

Ammonia is certainly easier to store than hydrogen, but it is not a liquid at STP. It liquefies at -33°C and 1 atm, or alternately at around 8 atm and room temperature.

Hmmm... 8 atm is certainly easier to imagine carrying around than 100s of atm to store hydrogen.

As a kid I walked through a barn where a leaky ammonia tank was stored. It was a farmer's ammonia sprayer for fertilizing corn. Not a very large one, and not a very airtight barn. 45 years later I still blink and cough at the thought. Whole different set of infrastructure and safety requirements compared to petroleum. But I suppose it could be managed.

 

[DEvens]

Hmmm... Other people are thinking ammonia.

https://www.ammoniaenergy.org/

 

[gmax137]

There are still environmental benefits to EVs, however, as burning fossil fuels in a power plant to generate electricity to power a car is overall more efficient and produce fewer emissions than burning gasoline in a small car engine.

Are you sure about that?

In fact, given that coal power plants are much more harmful to the environment and human health than gas-powered cars...

Seems to contradict the above? I really don't know what the relative emissions are.

given the extensive pre-existing electric grid in the US, requires minimal infrastructural change to implement wider adoption

I'm not so sure about that. Here's a little exercise that surprised me. Look at the energy transfer rate when filling up your car at the gas station. If you pump 15 gallons in say, 5 minutes, that's 3 gallons per minute. Gasoline has 114,000 Btu per gallon, so you are pumping 342,000 Btu per minute, or 20.5 million Btu per hour. That's 6,000 KW passing through the filling hose! Now its true the electric motor will be, say, three times more efficient than the gasoline engine, so you need "only" a 2,000 KW charging line.

Of course, we don't have to re-charge the cars as quickly as we re-fill the gas tank, but still

Replacing the gasoline we use in our cars with electricity is a great idea, but I don't think "minimal infrastructure change" is the right word for it.

Here's another exercise. Google says the US consumed 143 billion gallons of gasoline in 2018. Using the 114,000 Btu/gallon, that works out to an average consumption rate of 550,000 MW. Applying the factor of three its still 180,000 MW. Compare that to the total US electric generation of 3.82 trillion KW hr per year = 435,000 MW. So we'd need to increase electric production by 180/435 = 40 percent. Not trivial.

 

[Ygggdrasil]

Are you sure about that?

Here's a figure from the US Department of Energy:

(source: https://afdc.energy.gov/vehicles/electric_emissions.html)

However, it is true that in certain regions of the US with high usage of coal (e.g. in WV where electricity is produced from >90% coal), EVs offer minimal emissions benefits over gasoline engines.

Seems to contradict the above? I really don't know what the relative emissions are.

Here's the relevant argument quoted from the Techology Review piece on hydrogen I cited above:

A coal-fired generator releases more than 1,000 kilograms of carbon dioxide into the air for each megawatt-hour of electricity it produces. The best gas-fired plants, by contrast, release only about 350 kilograms of carbon dioxide per megawatt-hour generated.​

​

Similarly, one megawatt-hour of electricity from renewables, if used to make hydrogen for a fuel-cell vehicle, would save around 230 kilograms of carbon dioxide compared to a Prius running on gasoline. That is some 770 kilograms less than the savings from displacing coal power-and these savings can be achieved without spending hundreds of billions of dollars on fuel-cell vehicles and hydrogen infrastructure. As David Keith of Carnegie Mellon and Alexander Farrell of the University of California, Berkeley, concluded in a July 2003 analysis in Science magazine: “Until CO2 emissions from electricity generation are virtually eliminated, it will be far more cost-effective to use new CO2-neutral electricity (e.g., wind or nuclear) to reduce emissions by substituting for fossil-generated electricity.”​

(source:https://www.technologyreview.com/s/402584/hype-about-hydrogen/)

Note that the piece is from 2004, so it is possible that some of the numbers may have changed over time.

I'm not so sure about that. Here's a little exercise that surprised me. Look at the energy transfer rate when filling up your car at the gas station. If you pump 15 gallons in say, 5 minutes, that's 3 gallons per minute. Gasoline has 114,000 Btu per gallon, so you are pumping 342,000 Btu per minute, or 20.5 million Btu per hour. That's 6,000 KW passing through the filling hose! Now its true the electric motor will be, say, three times more efficient than the gasoline engine, so you need "only" a 2,000 KW charging line.

Of course, we don't have to re-charge the cars as quickly as we re-fill the gas tank, but still

Replacing the gasoline we use in our cars with electricity is a great idea, but I don't think "minimal infrastructure change" is the right word for it.

Here's another exercise. Google says the US consumed 143 billion gallons of gasoline in 2018. Using the 114,000 Btu/gallon, that works out to an average consumption rate of 550,000 MW. Applying the factor of three its still 180,000 MW. Compare that to the total US electric generation of 3.82 trillion KW hr per year = 435,000 MW. So we'd need to increase electric production by 180/435 = 40 percent. Not trivial.

That's true and a good point. However, installing fast charging stations is orders of magnitude easier than, say, creating national infrastructure to deliver hydrogen or ammonia (which was my point of comparison). While it is true that more widespread adoption of EVs would increase demand for electricity, some of that demand could be met without increasing capacity (for example, most people charge their EVs at home overnight when demand from other sources is low and most power plants are not operating at capacity). For example, consider this analysis:

Based on our estimates, the charging requirements for a fully electrified fleet of personal cars in Texas would be about 290 gigawatt-hours per day, less than the available surplus of generation capacity. In other words, the Texas grid could theoretically charge a fully electrified vehicle fleet today if vehicles were charged during off-peak hours.​

​

When we did the same analysis for California, however, we found that if EVs become the norm, it could push the total demand for electricity beyond the existing capacity of the Golden State’s grid.​

(source:https://www.citylab.com/transportation/2018/12/americas-power-grid-isnt-ready-electric-cars/577507/)

Overall, the analysis concludes "While EVs might increase the amount of electricity the U.S. consumes, the investment required to accommodate them may be smaller than it appears. Many regions already have sufficient generation capacity if vehicles are charged during off-peak hours. The energy storage on board EVs could provide the flexibility needed to shift charging times and help grid operators better manage the supply and demand of electricity."

While it is true that some regions might need to build additional capacity to accommodate EVs, the vehicle fleet will not be converted to an all-electric fleet overnight, so there is time to build capacity to meet the additional demand from EVs.

 

[TeethWhitener]

I dunno, hydrocarbons are just so much more energy dense than any other solution. I honestly think the ultimate solution is probably going to involve some kind of direct hydrocarbon fuel cell: marry the efficiency of an electric motor with the energy density of gasoline. But right now, the main option down that road is solid oxide fuel cells, which have their own problems (like only operating at temperatures above 800 C or so). And of course, one needs a carbon-neutral way to produce hydrocarbons, or failing that, a fuel cell that isn’t poisoned by biodiesel. So there’s still plenty of work to be done.

Just my two cents.

 

[BillTre]

That's true and a good point. However, installing fast charging stations is orders of magnitude easier than, say, creating national infrastructure to deliver hydrogen or ammonia (which was my point of comparison).

I recall an electric car company had proposed a method of rapid refilling by just changing a battery pack in the car.
The refill station would then take the battery out back to get recharged with a group before being recycled into some other car. (Would require some method to ensure battery charge/quality perhaps with testing by car).
This could be fast depending on how well the exchange is designed into the car and station. The conditions for recharging the batteries could be maximized for efficiency while still having a quick refill.

WRT one of the differences between the current sources for the petroleum industry and biofuels:
It is important to consider the sources and and the tie scales over which these fuels were built up and what it means to add them to the environment.
As has been said, biofuels, are remade from environmental materials (atmospheric components and light ultimately) over a relatively short time span.
Carbon components of fuels may:

• exist as standing stocks of carbon in a dynamic form (forests and other life forms)
• sequestered in geological formations (oil, coal, carbonate deposits)
• return directly to the atmosphere by burning.
• return to the atmosphere but rotting (complex biological processes of decay)

The carbon cycle is made of these kinds of transfers between different states.
Normally the rates of transfer between the different places in the cycle will determine the steady states amounts in different forms (atmosphere, rock, oil, coal, peat; for example).
Suddenly adding a bunch of carbon to the atmosphere from another source can create problems if the rate at which the carbon is added exceeds the ability of natural processes to remove it.

Biofuels are ideally made by removing the equivalent amount of carbon from the atmosphere.
This is why it is called carbon neutral.
Its not surprising to me that carbon added to the atmosphere by burning fuels, that were buried in the ground for millions of years, and were probably produced over millions of years (to make the geological deposits), can exceed the normal rates at which natural processes can restore atmospheric levels to "normal".

An example of this (but involving rapid changes in atmospheric sulfur concentrations by changing atmospheric sulfur concentrations by rapidly changing geological deposits into atmospheric gas is the dinosaur killing Yucatan impact (NYTimes and the PNAS article ($10 paywall, original article)). It volatilized a huge amount of sulfur in geological deposits which caused an estimated 30 year long decrease in the Earth's temperature.

There are many other chemical cycles found in nature which could help frame inform other potential fuels:
sulfur
nitrogen

NO and NO₂ can have biological effects (NO₂ laughing gas).
Any use of some chemical that could leak out and build in a contained area will need a standard set of precautions for its use (venting, alarming or whatever). Engineers do this in lots of cases already.

Liquid fuels can pack a lot of energy.
However biofuels can do that (plants or plant-like biological processes), plus draw much of their carbon from the atmosphere. Thus it is not an addition of carbon to the atmosphere from a different source.

There should be a maximal rate at which normal natural processes could remove carbon from the atmosphere. The amount over that should give you a rate of change.
Ultimately, this will be limited by the solar energy input to the globe, plus any interesting human tricks that might arise.

Other ongoing environmental changes also also affect this, including:

• continued population growth (drives greater energy demands and resource use)
• reduced natural environments reducing carbon fixation rates. (I am guessing here that a natural environment will be a more carbon sequestering one than a human modified environment.)

 

[TeethWhitener]

NO2 laughing gas

N₂O is laughing gas. NO₂ definitely won’t make anyone laugh (it forms nitric acid on contact with water).

 

[BillTre]

N₂O is laughing gas. NO₂ definitely won’t make anyone laugh (it forms nitric acid on contact with water).

Opps. Was going to check that, but forgot.

 

[russ_watters]

Are you sure about that?

Seems to contradict the above? I really don't know what the relative emissions are.

It's all about the margins: adding an electric car today draws power from the existing mix of the grid at the current CO2 production rate (mostly fossil fuel electricity) -- or current production addition rate (which is still mostly fossil fuel). Subtracting a coal plant (or adding a nuclear plant...) is entirely a CO2 reduction. So it's much, much better for carbon reduction to focus on electricity than spend effort on electric cars. Still:

As you can see, many of the solutions above have as a pre-requisite the development of green, carbon-free/carbon-neutral sources of electricity, so it seems like most of our efforts should be focused there rather than the more challenging problem of producing green carbon-free energy that is also compact and portable.

Agreed. De-carbonizing the grid is much more important to the global warming timeline than implementing electric vehicles. Electric cars have two major promises, and today neither are being realized in any significance:
1. Energy cost savings -> swamped by purchase price premium.
2. CO2 savings-> insignificant due to using fossil fuels to charge them.

Still, given that EVs are an insignificant portion of the equation today, I do support continued development, in particular by private companies. These efforts are funded by enthusiastic fans and because they remain small don't have a major impact on the bottom-line. And they are necessary to develop EVs to maturity. Put another way: I'm fine with a relatively few people voluntarily donating a ton of money to Tesla to be alpha/beta testers of its technology, because it'll take a decade or two until it matures, and that's as good a way as any to fund its development without getting in the way of grid conversion (note to Congress: need to actually start the grid conversion...). Then when it's ready to be widely released, hopefully the grid will be ready to provide it with clean power.

EVs are the most commercially viable as demonstrated by the robust market for EVs and gas-electric hybrid vehicles and are likely the way forward in the near and perhaps far future. Deployment of EV technology does not require major infrastructural changes, and as the grid becomes more green, so do EVs.

Totally agree. The essential need for a stable liquid fuel exists, but not for road vehicles. EVs have enough promise and small enough downsides that if we ran out of oil tomorrow we could switch without extraordinary pain. Airplanes, on the other hand, are the primary use of liquid fuel that would be massively impacted by its loss. This is also why I think the downsides of hydrogen are not as big as often speculated; companies that require perfect safety (airlines) tend to be better at providing good safety than everyday people, and with care, hydrogen can be a pretty good fuel for airline transportation.

 

[Dale]

Summary: Is there an alternate fuel that de-emphasizes carbon?

Is there a potential fuel, for some kind of engine, not necessarily similar to existing car or diesel engines, that does not have carbon in it?

Yes. These have been proposed and studied. Essentially, the energy that makes a fertilizer bomb explode can be used as a fuel instead.

https://doi.org/10.1002/anie.201510618

 

[x_engineer]

That's a tough list of constraints, but you forgot to include "inexpensive"!

I think if such a chemical existed, it would already be obvious and we'd already be using it. You listed air and water as the sources, which pretty much limits the constituents to oxygen, hydrogen and nitrogen, and their chemistry is already very well known. And plain hydrogen is the obvious choice from that list.

Personally, I don't see the gas vs cryogenic liquid thing to be that big of a deal. It even has its benefits, like providing free cooling.

Summary: Is there an alternate fuel that de-emphasizes carbon?

Is there a potential fuel, for some kind of engine, not necessarily similar to existing car or diesel engines, that does not have carbon in it? That is, that you might manufacture from water and air without having to concentrate the carbon dioxide somehow. And that's liquid at ordinary temperatures and pressures one might find walking around in an ordinary town.

Yes, I am aware of the Dunning-Kruger effect. Talk to me like an ignorant 9 year old if it seems appropriate. My last chemistry class was in first year undergrad, and that was [mumble] years ago. And I got a crappy mark.

But imagine: A windmill generates this stuff. Intermittently possibly. As its inputs it needs air and water. The water might well be from rain or a nearby well. Supposing it was a liquid at normal temperature and pressure. It could collect in a nice holding tank. The tank would not need to be pressurized or cryogenically cooled. Then once a month a tanker truck could come collect it for use in car engines. Using it in engines would then return it to water and air.

It would be especially interesting if it was useful in aircraft engines. Again, not necessarily of the existing design engine.

Is there any such chemical?

As posted in another thread, that is a tough list of constraints, and probably unnecessary for your purposes.

Liquid nitrogen can be used as a "free energy" distribution fuel. I put it in quotes, because you would not be distributing "energy" in the academic physical sense. But most of the time, we don't care about "energy" - we care about "free energy" i.e. "work". At normal ground level ambient temperatures, the "free energy" available from a kilogram of LN2 is about 1/10 that available from gasoline, which may or may not be an issue for you. The one thing you can not use it for is space heating - but cooling works!

LN2 is cheap, non-polluting, and a distribution mechanism already exists.
You can even generate it at home if you have another source of "free energy" (like electricity over wires).

Niket Patwardhan

 

[anorlunda]

So we'd need to increase electric production by 180/435 = 40 percent. Not trivial.

That's approximately correct. Maybe only 33% in terms of MWe capacity. Maybe more than 50% in terms of money. More on the money side because every distribution line every transformer on every street, nearly every electric service entrance in every home would need to be upgraded if all transportation was electric.

It used to be that electric power required 25% of all capital investments in the USA. I've been unable to find a recent number. So the infrastructure investment challenges associated with EV takeover are huge. If done in time as short as one decade, it means really massive spending.

Edit: This figure can help the discussion. Source

https://www.eia.gov/todayinenergy/detail.php?id=41093

 

[BWV]

One point - the EIA’s 11.5% renewable number includes hydro and biomass. solar and wind, where the growth of new generation capacity is, accounts for about 3.5% of total generation

 

[anorlunda]

That EIA figure from #23 is very useful. Does anyone have a link to analogous breakdown for the EU? How about one for the entire planet?

 

[TeethWhitener]

That EIA figure from #23 is very useful. Does anyone have a link to analogous breakdown for the EU? How about one for the entire planet?

I made these a long time ago, they're at least a partial answer to your question.
(Key and link are in the "world energy use" file.)

 

[Dale]

Yes. These have been proposed and studied. Essentially, the energy that makes a fertilizer bomb explode can be used as a fuel instead.

https://doi.org/10.1002/anie.201510618

Actually, now that I read the paper more in depth, they describe this as a hydrogen fuel where the nitrogen is used to store energy in bonds with hydrogen. I am not sure how the fuels community classifies fuels. It may be that a nitrogen fuel is one where the energy is in the nitrogen-nitrogen bonds.

 

[DrStupid]

It may be that a nitrogen fuel is one where the energy is in the nitrogen-nitrogen bonds.

That would mean that NH₃ is neither a nitrogen fuel nor a hydrogen fuel (because there are neither N-N nor H-H bonds). It makes more sense to look at the oxidation states and how they change when the fuel is burned. In case of NH₃ nitrogen is oxidized from -3 to 0 (disregarding the formation of nitrogen oxides) whereas hydrogen remains unchanged at +1.

 

[TeethWhitener]

Got a request for a link to the source of the data in post #26:
http://www.tsp-data-portal.org/Breakdown-of-Electricity-Generation-by-Energy-Source#tspQvChart

 

[Dale]

That would mean that NH3 is neither a nitrogen fuel nor a hydrogen fuel (because there are neither N-N nor H-H bonds). It makes more sense ...

I agree. I think that I would also characterize this as a nitrogen fuel because the main byproducts are water and N2. Carbon fuels produce water and CO2.

I wonder if the characterization in that paper is standard or if they had some specific reason to describe it as they did.

 

[anorlunda]

If climate change is the goal, then the energy/pollution caused by production of the fuel is just as important than the burning of the fuel.

 

[Vanadium 50]

Two quick comments:

Hydrogen is commercially produced from methane, with CO2 as a byproduct. It would be better to use the methane directly: less energy loss for the same emission. Only a small amount is produced through water electrolysis.

Ammonia is nasty stuff. It's one of the most dangerous chemicals today - probably just under carbon monoxide. The reasons CFCs were introduced as refrigerants in around the 1920's is because people were dropping like flies from ammonia accidents.

 

[Vanadium 50]

I was going to go on a long screed about ammonia releases, but then I realized I would just be...venting.