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Could the Hydrogen Economy Run on Ethanol?

  • Plans for a fuel cell car running on ethanol look like a clever way to circumvent the obstacles faced by other fuel cell vehicles.
  • However, it is not clear that ethanol’s perceived logistical benefits or emissions profile would give Nissan an edge in the competitive market for green cars.

Japan’s Nissan Motor Co., Ltd. made headlines this week when it announced plans to produce a fuel-cell car that would run on ethanol, instead of hard-to-find hydrogen. As reported by Scientific American, the company expects to commercialize this approach by 2020, even though competitors like Toyota already have fuel cell cars in their showrooms. It’s an interesting choice. Ethanol seems to offer logistical advantages over hydrogen, but the technical challenges involved aren’t trivial, nor is ethanol without drawbacks from an energy or environmental perspective.

Fuel cells have long promised a different and potentially superior path to electrifying automobiles, compared to battery-electric vehicles (EVs) with their limited range and relatively long recharging times. One of the biggest obstacles has always been the lack of infrastructure and supply–hydrogen must first be liberated from water, methane or other compounds–and the problems of storing sufficient quantities of it on board. I’ve driven prototype fuel-cell vehicles (FCVs) and found the experience pretty similar to driving a regular car, as long as you have a hydrogen filling station handy.

Nissan makes the case that ethanol (chemical formula C2H6O) is much easier to source and distribute than gaseous hydrogen, and the process for making it give up its hydrogen is routine, at least under laboratory conditions. However, as the alternative energy research subsidiary of my former employer, Texaco Inc., found in pursuing a similar concept with gasoline, it’s one thing to do this in a bench-scale device and quite another to do it in a size and shape that will fit easily and safely in a car and run as reliably as an internal combustion engine. I suspect Nissan’s engineers have their work cut out for them for the next four years.
The bigger questions about this approach are more basic: Does it make sense from an economic, energy and environmental perspective, and can it find a large enough market? Consumers already have a wide range of green alternatives from which to choose, ranging from Prius-type hybrids (gasoline only), plug-in hybrids (gasoline + electricity) and battery EVs, not to mention the continuous improvement of non-electric cars.
Nissan didn’t include many numbers in the documents accompanying its press release, but the chemistry and math involved are pretty simple. At 100% efficiency, a gallon of ethanol could produce just under 0.8 kilograms (Kg) of hydrogen (H2) using the standard steam-reforming process. The best efficiency I could find for this ethanol-to-hydrogen conversion was around 90%, so in the real world that gallon of ethanol would yield around 0.7 Kg of H2–enough to take Toyota’s Mirai FCV about 46 miles. That’s pretty good, considering that same gallon in a Chrysler 200 equipped as a flexible fuel vehicle (FFV) would drive an average of just 21 miles. Fuel cells are much more efficient than internal combustion engines.
The economics of operation don’t look bad, either. If we use today’s average US price for E85 (85% ethanol + 15% gasoline) of $1.87/gal. as a proxy for an ethanol retail price, that equates to around 4 ¢/mile, using the Mirai’s published fuel economy data. That’s about 15% cheaper than a Prius on regular gasoline at this week’s US average of $2.40/gal., but it’s also around 10% more expensive than a Nissan Leaf using off-peak electricity in northern California.
Emissions are trickier to assess. There’s a lively and growing controversy about whether biofuels produced from crops can truly be considered carbon-neutral, even in places like Brazil where the yields from sugar cane are so high. There’s much less controversy that the production of most US ethanol from corn is anything but a net-zero-emission endeavor. Corn requires fertilizer sourced from natural gas, and ethanol refineries consume gas (or coal) and electricity in their production process. In any case, when Nissan characterizes their planned ethanol FCV as having “nearly no CO2 increase whatsoever“, they are either oversimplifying a very complex discussion or taking a large leap of faith.
We can count the CO2 coming out of the tailpipe of such a car, and it would need a tailpipe because the onboard ethanol converter would emit about 12.5 lb. of CO2 for every gallon of ethanol converted to pure H2, plus some CO2 from the ethanol burned to heat the unit. My back-of-the envelope calculation gives a figure of 135 grams of CO2 per mile, or 20% lower than a Toyota Prius on gasoline. It would not be a Zero Emission Vehicle (ZEV), though of course an EV running on average grid electricity isn’t really a ZEV, either, except in isolated regions or at specific times of day.
Even if there aren’t any deal-killers here, I’m skeptical about Nissan’s fundamental assumption that the ethanol infrastructure for their FCV would be that much easier to develop than the H2 infrastructure other FCVs require. That’s because of the cost and ownership structure of the retail fuels business, which as I’ve argued previously helps explain why your corner gas station is unlikely to sell E15 (85% gasoline, 15% ethanol) any time soon, despite the EPA having approved it for newer cars.
At least in the US, most gas stations are owned by small businesses, not by the oil companies whose brands they display. Margins are slim, and these folks don’t have deep pockets, so adding a new fuel like pure ethanol or the ethanol-water mix that Nissan suggests, poses a difficult business decision: Do you take over an existing tank and stop selling diesel fuel, or premium gasoline with its high margins? Or do you rip up the forecourt to add a new tank, which entails being out of business for months–or even longer if you discover that one of your existing tanks is leaking? Either way, the investment costs and disruption to current customers are significant, in exchange for selling what at first would certainly be a low-volume product. When I was in the fuels supply & distribution business, we would have called that kind of decision a “no-brainer.”
If Nissan can’t encourage enough service stations to add ethanol or an ethanol/water blend–E85 would not work–to their product mix, do they start their own service station network? That seems unlikely. And if you buy one of these cars in a few years, should you carry a case of vodka in the trunk as an emergency range-extender? That’s only half-facetious.
I give Nissan credit for pursuing a novel option for making fuel cell cars more viable, as an alternative to today’s range-limited EVs. Ethanol looks like a cost-competitive source of hydrogen, and it is at least easier to store than H2 gas or liquid H2. However, they face practical and marketing challenges that might well offset most of the advantages the company claims to see. The ethanol FCV could encounter the same chicken-and-egg dynamic as FCVs running on hydrogen, or indeed any new model requiring a fuel that is not distributed at scale today. It will be interesting to watch their progress.
Photo Credit: Maurizio Pesce via Flickr
Geoffrey Styles's picture

Thank Geoffrey for the Post!

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Bob Meinetz's picture
Bob Meinetz on Jun 20, 2016 4:21 pm GMT

Geoffrey, according to An Alternative to Gasoline: Synthetic Fuels from Nuclear Hydrogen and Captured Carbon from MIT’s Center for Advanced Nuclear Energy Systems (2007), we could replace liquid fossil fuels in the U.S. with ethanol synthesized by 670 1.5GW fast-neutron reactors, effectively zeroing out U.S. ground transportation’s contribution to climate change. It would take 1,511 such reactors to replace liquid fossil fuels globally.

To make matters better, fast-neutron reactors like the one Bill Gates is building in China will run for centuries on the spent fuel stored in dry casks at existing nuclear facilities. What are we waiting for?

Engineer- Poet's picture
Engineer- Poet on Jun 20, 2016 6:21 pm GMT

Green Freedom still lives, I see.  I find it ridiculous to talk about 1 TW of new nuclear plants to make synthetic hydrocarbons when 180 GW would electrify ground transportation and make the hydrocarbons obsolete.  It’s almost as if… somebody was trying to keep the existing system in place and make the replacement so costly that it would be abandoned, leaving us right back where we are now.

Rick Engebretson's picture
Rick Engebretson on Jun 20, 2016 7:49 pm GMT

I’m not sure a transportation vehicle for a billion customers is a necessary goal for such a system. The basic fuel chemistry to electric power generation system could instead replace a lot of diesel generators around the world and make a lot of people happy. Thanks Geoff for the heads up.

Bob Meinetz's picture
Bob Meinetz on Jun 20, 2016 9:58 pm GMT

EP, that would be a pretty roundabout way to get where you wanted to go, and I don’t envision anyone plopping down several $trillion to do it all at once (the roundabout conspiracy theories are the ones to steer clear of).

In our existing system electric vehicles are already replacing liquid fuel in many locales and for many applications; in northern latitudes and for specialty applications (heavy trucking, construction, recreation) going 100% electric is going to take a while. In the meantime, keep those nuke plants running 24/7 and redirect their nighttime generation to synthesizing ethanol.

Bob Meinetz's picture
Bob Meinetz on Jun 20, 2016 10:05 pm GMT

Agree Rick, bring ethanol generated from the sun or nuclear synthesis to people far off the grid now getting their energy from burning the three “Ds” – diesel, deadwood, and dung – and dying from it. Maybe that should be the fourth “D”.

Rick Engebretson's picture
Rick Engebretson on Jun 20, 2016 11:03 pm GMT

Thanks Bob.

My assigned grad research was hydrogen exchange kinetics at high pressure (> 100,000 psi) in proteins. There were several parameters effecting exchange rates, but the lab was most interested in macromolecular conformation. Temperature, pressure, solution properties, a lot of variables. I added blasting proteins with different electric field and sound frequencies just to see if protein configuration is “addressable” (they are).

I suspect it’s possible to use fuel cell heat to transform macromolecular cellulose to various alcohols, etc. It is certainly possible to use nuclear heat to produce fuels from biomass. Same for concentrated solar, as I’ve suggested. Of course the engineering is where the rubber meets the road, and it’s all theory and fantasy until then. It short, we don’t need synthesis if we start from “deadwood.” But we need engineering, and Nissan is doing some.

This is a very different electrification pathway from windmills and solar PVs.

Bob Meinetz's picture
Bob Meinetz on Jun 21, 2016 12:04 am GMT

Interesting, Rick. Obviously if photosynthesis can get the process part of the way there, that’s beneficial.

What I haven’t seen is a way to get enough non-fossil carbon necessary to recreate the petajoules of fossil energy the world uses every year from plants, on an ongoing basis. Is there one – even theoretical – that you’re aware of?

Rick Engebretson's picture
Rick Engebretson on Jun 21, 2016 1:27 am GMT

The only concepts I can offer are what you already know.

First, we enjoy a trend of increasing energy consumption efficiency. Lighting, buildings, manufacturing, transportation, possibly food, communication are going the right way. So maybe we don’t need the same energy consumption, at least per-capita.

As regards the conversion of biomass to serious fuels, it takes a lot of energy input, as you know. My gimmick of solar fuels has a little quantum mechanics in it. A photon from the sun has a real kick in it that mainstream heat doesn’t provide. The O-H vibrational stretch mode is high frequency near infrared. Basically, cellulose is raised in energy content until it isn’t cellulose anymore. As regards pressure processing, steel strength is the effective limit of simple pressure containers, and we know a steel saw cuts high molar volume wood, so hydraulic extrusion might be helpful.

I’m not trying to be cute and evasive, but I have a batch of concrete and rock in the morning. My calculation is focused on how much work I can do before a heart attack. I still have old books around, and might open them again some day.

Nathan Wilson's picture
Nathan Wilson on Jun 21, 2016 2:19 am GMT

While Nissan’s press release mentions ethanol being “widely available in countries in North and South America, and Asia”, both of the “VP” presentations specifically call out Brazil, and sugar cane ethanol. So while the Nissan vision of BEVs and biofuel-FCVs fulfilling complementary roles in the market is compelling (small BEVs with short range, biofuel for trucks and vans and long range), Brazil is apparently their initial target market, not the US.

Nissan’s choice of solid-oxide fuel cells (instead of PEM) is interesting. This is the type that Bloom uses in their fuel cell system for stationary power. The high (900 C) temperature of these devices allows them to run on methane or ammonia with no need for a separate reformer; they also don’t require catalysts made from platinum or other rare metals. The high temp also implies a long warm-up time; perhaps the vehicle would run initially on batteries so the warm-up time would not be noticed.

Of course the “hydrogen economy” isn’t just about using hydrogen as a transportation fuel. One of the main selling points (relative to BEVs) is that hydrogen synthesis from water and off-peak electricity can be used to balance supply and demand in a sustainable electric grid (including otherwise-intractable seasonal imbalance implied by variable renewables). Using biofuel for transportation does not have this same benefit. Electro-hydrogen can be incorporated with biofuel processing to re-use the waste CO2 which is released in the process, but since E100 involves a build-out of new fuel infrastructure anyway, why not skip the extra step and use the hydrogen for fuel (or easier-to-store carbon-free ammonia, which is made from H2 and air), thus avoiding the enormous land-use of biofuel production?

Nathan Wilson's picture
Nathan Wilson on Jun 21, 2016 3:32 am GMT

Supplying clean cooking fuel to people in off-grid villages is a great application for ammonia fuel. If solid-state ammonia synthesis (a process which uses a direct ammonia fuel cell, run in reverse) which has already been demonstrated at lab scale can be scaled up, then ammonia can be made from water, air, and electricity, by a refrigerator-sized device sitting in back of the local general store. At the same time, the solar-dominated micro-grid can decommission its diesel back-up.

Lest anyone worry about the safety implication of a toxic & stinky fuel like ammonia, be assured that ammonia’s flame-resistance (except in special catalyst-assisted burners) offers a safety benefit that completely offsets the toxicity hazard.

Engineer- Poet's picture
Engineer- Poet on Jun 21, 2016 4:39 am GMT

EP, that would be a pretty roundabout way to get where you wanted to go

So’s using 670 * 1.5 GW = 1.005 TW of nuclear power to make synthetic ethanol.  Both schemes look designed to be rejected, and make all nuclear proposals look bad.

I don’t envision anyone plopping down several $trillion to do it all at once

Well, if it had been part of the run-up of the current US national debt at least we’d have something to show for it.

Not that fleets of fast-breeders aren’t a great idea.  I need to dig up numbers again, but I suspect that a half-dozen S-PRISMs could supply all of ConEd’s steam requirements and still cogenerate a large amount of electricity.  Manhattan could go carbon-free.

keep those nuke plants running 24/7 and redirect their nighttime generation to synthesizing ethanol.

There’s where you and I part company.  Nuclear-to-fuel appears to be a mistake, period.  Using nuclear process heat to break down the lignocellulose in waste streams and converting THAT to ethanol kills two birds with one stone (MSW volume reduction and stabilization plus a fuel stream), but fully-synthetic EtOH from air and energy should probably stay confined to the lab.

Bob Meinetz's picture
Bob Meinetz on Jun 21, 2016 2:02 pm GMT

EP, I know better than to part company with people who understand a topic better than I.

Your recommendation on using waste heat to break down lignocellulose is akin to Rick’s pre-waste idea of converting plant matter to ethanol, using solar or another source of energy – basically, that starting from scratch makes the “juice not worth the squeeze”. But since we’re going to the effort, it seems not inconceivable that we’ll uncover a more efficient process than Fischer-Tropsch which might yield an end product more energy dense than ethanol. Some carbon-neutral chemical fuel with a more realistic chance of competing with fossils.

It’s getting harder to hold out hope for nuclear here in California – in just over a week, California’s sole remaining nuclear plant, Diablo Canyon, will be dead in the water. The fix is in, with the State Lands Commission scheduling a vote on lease renewal for sometime after midnight to discourage public participation (#96 on the agenda – dead last). After 2018 the $11 billion plant will be forced to shut down, effectively handing Sempra Energy a fossil-fuel lock on California’s electricity future.

The sister of the Governor of California sits on Sempra’s Board of Directors.

Bob Meinetz's picture
Bob Meinetz on Jun 21, 2016 4:55 pm GMT

It’s official – PG&E to Close Diablo Canyon Power Plant

Nathan Wilson's picture
Nathan Wilson on Jun 22, 2016 4:15 am GMT

Nuclear-to-fuel appears to be a mistake, period.

Yes, fuel synthesis using baseload power seems hopeless for the US, especially at today’s oil prices.

But if oil returns to $100/barrel, and if we institute a strong disincentive for fossil fuel generated electricity, then perhaps the grid could support off-peak electricity sales at $15/MWh at 20% capacity factor, then you’d just need a fuel plant that could be built for $0.60/Watt of fuel output plus another 5%/yr in O&M (assumes 5% interest and 50% efficiency).

Slim margins, to be sure. But to match supply and demand, a grid either needs a substantial amount of flexible generation (hydro & fossil), or it will create a lot of otherwise unneeded off-peak electricity.

Note though that since it uses only off-peak electricity, this system is limited to about 20% of the total electricity supply, so it is no threat to the BEV industry. It will however make them cleaner by helping to get fossil fuels off the grid.

Geoffrey Styles's picture
Geoffrey Styles on Jun 22, 2016 7:19 pm GMT

I agree that we could do any number of useful things with abundant nuclear power. However, as yesterday’s announcement concerning Diablo Canyon made clear, we will be lucky if new additions even balance retirements in the US over the next decade or so. Nissan’s fuel cell cars will run on ethanol made from corn in the US, and perhaps from sugar cane elsewhere, like Brazil. We should evaluate them on that basis.

Geoffrey Styles's picture
Geoffrey Styles on Jun 22, 2016 7:23 pm GMT

Good idea, Rick. A highly efficient genset running on ethanol could be a boon to many off-grid locations, and perhaps more than solar or small wind where 24/7 capabilities are needed and the cost of batteries can’t be justified. Another market for Nissan to consider.

Bob Meinetz's picture
Bob Meinetz on Jun 22, 2016 8:17 pm GMT

Geoffrey, I live at the south end of California, but talking to people in the San Luis Obispo area you’d think a relative had died. There is not only an economic attachment to Diablo Canyon, but an overwhelming sense of pride in what it means for fighting climate change.

I decline to admit that we will be lucky with anything, because it will take a lot of work to keep natural gas interests from closing all the nuclear plants in the country. That’s the apparent strategy, and there is a lot of money behind it. Are we capable of standing up to monied interests in defense of the environment and “any number of useful things”? Seems both are causes worth fighting for.

Rick Engebretson's picture
Rick Engebretson on Jun 22, 2016 10:18 pm GMT

I won’t claim the idea, but thanks the same Geoff. About 25 years ago the head of the National Rural Electric Cooperative Assn. sent a beautiful little book with pictures describing their plan. Today, of course, they would send an internet link. There probably isn’t enough wire in the world to power global farms, so cities fill up.

I’m sure you will agree, many wonderful people keep our system working. Always looking for a better way. Yet politics sings their song variant, “You got to accentuate the negative, eliminate the positive.” I joined TEC after a google search of fuel cells found your article many years ago. Always appreciate your work.

BTW, concrete project and heart OK. A shed for a 1951 Allis Chalmers WD45. The liquid filled tires almost killed me once so I need a hoist. My next project is rediscovering sickle bar mowers. Ideal “carbon sequestration” and water/fire management tools.

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