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Sharing the Road to Zero Emissions, Part 1: More ZEVs Provide Customer Choice

Morry Markowitz's picture

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Bob Meinetz's picture
Bob Meinetz on November 6, 2015

Morry, I understand you’ve got a job to do.

My job as an environmental activist (one of them) is to debunk the nonsense that hydrogen-powered vehicles, which you lump together with battery-electric vehicles using the hyperbolic and meaningless acronym “ZEVs”, are remotely comparable to BEVs in terms of emissions.

I’ve posted it before, I’ll post it again: an analysis using the Dept. of Energy’s GREET Model (“Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation”) – the most comprehensive life cycle emissions model in existence – shows that liquid hydrogen-powered vehicles generate 38% higher carbon emissions than battery-electric vehicles charged by the average U.S. electricity mix. In California, emissions would be about 58% higher than a BEV; using a completely nuclear/renewables-powered mix they would be 100% higher – because driving a BEV on that kind of mix generates no significant carbon emissions at all. Clean as a whistle.

It’s true while driving a hydrogen-powered vehicle only water comes out of the tailpipe. Where do all the greenhouse gases (GHGs) come from? To get the hydrogen used to power these vehicles you’re promoting, fossil fuel methane (CH4) is steam-reformed, at a perilously-high energy cost, stripping the hydrogen atoms from their tetrahedronal cell around the carbon atom. The carbon then combines with oxygen to make the GHG carbon monoxide (CO), which is released into the atmosphere and quickly begins doing its part to destroy the climate.

The stripped hydrogen atoms, which combine in pairs as H2, must then be compressed to 8,000 psi (at a perilously-high energy cost) and transported to filling stations by large, specially-designed trucks (at a perilously-high energy cost).

Waste, waste, waste – all accounted for in the GREET model, and all at the expense of the environment.

Nathan Wilson's picture
Nathan Wilson on November 8, 2015

Bob, while I agree that BEVs will play a larger role in reducing transportation CO2 emissions than carbon-free fuels, especially in the US, there is still an important role for these fuels.

I should first note that I used the term carbon-free fuel in order to include hydrogen (H2) and its much more practical cousin, ammonia (NH3).  As you point out, liquefying or compressing hydrogen is energy intensive; it turns out to have about the same energy cost as converting the hydrogen to ammonia by adding nitrogen (which can be captured from the atmosphere for very low cost, enormously easier than capturing CO2).  Ammonia is a much better transportation fuel, since it has double the energy density of 10,000 psi hydrogen, and the pressure is much lower, so the tanks can be formed into more convenient shapes.  Easier transportation and storage means that ammonia will be much cheaper at the point of sale than hydrogen.  Plus it doesn’t require expensive fuel cells, as it can be burned in modified internal combustion engines with high compression (therefore high efficiency) like diesel engines, except it burns cleaner than diesel or hydrogen.  Ammonia fuel is the easiest solution for seasonal energy storage, since with refrigeration, in can be stored in warehouse sized unpressurized tanks.  See NH3 Fuel Association.

As to carbon-free fuels, as a fossil fuel producing country, we’ll likely be the last to switch.  But for countries that lack domestic fossil fuels, producing synfuel from renewable electricity and nuclear power is a potentially money-saving alternative to importing fossil fuel.  Generally, displacing fossil fuel from the electric grid is the first priority.  But as sustainable energy becomes the dominant electricity source, there will be times of excess production.  This excess must either be “curtailed” (i.e. wasted, which blocks further growth in sustainable electricity), or sold at a discount to a dispatchable synfuel plant.  As the synfuel plants become larger and more cost effective, they’ll be able to afford higher priced electricity, which increases the amount of electricity available to them (growing the sustainable electricity segment and squeezing out more fossil fuel electricity).

In developing countries with low wages and little domestic fossil fuel, it should be possible to build synfuel plants than run not just on off-peak electricity, but on baseload power, which means the supply can grow with demand.  This is because low wages means cheap nuclear and renewable power, and it means imports will be much less affordable than domestic products.

For rich countries, synfuel production will be only a small part of the electricity demand, hence there is no need to introduce synfuel passenger cars; heavy duty trucks, trains, buses, tractors, and construction equipment will be able to use all of the available supply (our diesel fuel usage of 2939 kbarrels/day equates to 177 GW).  An ammonia truck is not as sexy as a fuel cell car, but it is a lot more practical.

There has been plenty of work on using ammonia fuel in heavy trucks; it works fine (see this presentation on engine lab testing from the Iowa State University, or this description of an Italian designed battery-ammonia hybrid truck).

Jim Baird's picture
Jim Baird on November 10, 2015

Morry, as I pointed out here, converting the heat accumulating due to global warming – principally in the ocean – to power and moving the balance to the deep may be the only way we can meet commitments to keeping to a less than a 2C temperature increase. To get this ocean generated energy to market however requires the conversion of electricity to an energy carrier. There are strong arguments that this carrier should be ammonia but like you I favor hydrogen because it is as much a water carrier as and energy carrier and there is a more concerted effort in the automobile industry for its use.

There is a real climate case to be made for hydrogen but as Bob points out that is undercut by steam reforming of methane. Electrolysis of sea water using OTEC power on the other hand may well be a do or die situation. 

The most efficient way to produce compressed hydrogen is to perform electrolysis in deep water. When performed at a depth of 1000 meters, as would be the case in an OTEC situation, the gas arrives at the surface pressurized to 100 bar. 

Full capacity OTEC -14 terawatts – using the “supergreen” electrolysis technique developed by a team from Lawrence Livermore Laboratories would also sequester about 79 billion metric tons of carbon dioxide each year.  

That amount of power would produce 1.8 trillion kilograms of hydrogen through the electrolysis of 16 trillion kilograms of water and this hydrogen, when reconstituted on land through the production of energy in a fuel cell or by burning in a combustion engine, would provide every person living on the planet 600 gallons of water annually.

A widely-used model estimates the social cost of anthropogenic greenhouse gas emissions at $326 trillion by 2200.

One example of the driver for these these cost was Hurricane Patricia, the strongest Pacific Hurricane ever to reach land.

The heat that powered that and like storms when driven to a depth of 1000 meters would no longer be available to cause havoc and the coefficient of expansion of sea water at that depth is half that of the surface so sea level rise would also be reduced.  

A new University of Cambridge study shows that melting permafrost will release sufficient carbon dioxide and methane to increase that cost by an additional $43 trillion.

Tropical heat moved to the deep also can no longer move to the poles to melt icecaps or permafrost.

Technology that slows or reverses global warming can not only prevent these losses it is the strongest incentive for the development of a hydrogen economy.

Bob Meinetz's picture
Bob Meinetz on November 10, 2015

Nathan, I went to the GREET model to do a lifecycle analysis on ammonia, and the only place NH3 appears is in fertilizer calculations for biofuels. Nowhere to be found in a list of 65 liquid fuels (dimethyl ether and others more exotic are included). What in your opinion is the resistance to ammonia as a transportation fuel? It’s apparently quite toxic in anhydrous form, especially for aquatic life. But so is gasoline.

We’re on the same page with nuclear synthesis of liquid fuels. If I haven’t already recommended this to you, check out this 2006 MIT study, An Alternative to Gasoline: Synthetic Fuels from Nuclear Hydrogen and Captured CO2. Costs $50, but I took the plunge and wasn’t disappointed.

Researchers B.D. Middleton and M.S. Kazimi calculate we could move the entire country off fossil fuels with ~600 nuclear plants creating synthetic ethanol from ambient CO2, ~820 plants for methanol. Fewer than other estimates I’ve heard. Includes a hypothetical transition scenario – and a section on the potential for using nuclear energy to extract oil from tar sands (?).

Nathan Wilson's picture
Nathan Wilson on November 11, 2015

What in your opinion is the resistance to ammonia as a transportation fuel?

I think the main factor is the one that is common to all syn-fuels (including coal or gas to liquids and bio-ethanol): high plant capital cost and highly volatile (sometimes very low) price for the petro alternative.  Supportive government policy will help with this.

All fuels made from electricity will have high cost.  This can be addressed by putting the fuel plants in countries with low labor cost (hence low capital cost).  Look to China to lead, once their sustainable electricity industry is growing fast enough to end coal-fired power plant construction (China already leads on coal-to-methanol).

The ammonia specific factors, toxicity and incompatible infrastructure:  toxicity is less of a problem for heavy duty trucks, given the professional operators (similar to agriculture, which uses ammonia fertilizer today).  Ammonia passenger cars can be introduced later, with stay-in-the-car robotic refueling, which people will want anyway (has been demonstrated with hydrogen already).  Infrastructure transition is not costly given a 20 year transition, and can be made to happen with government policy (same as ethyl-> unleaded, unleaded->E10, E10->E85).

The infrastructure challenger is easier with ammonia than hydrogen, since transportation via truck is much easier with ammonia than hydrogen (like 6x more Btus per truckload), as is retail storage.  Pipelines work for either, but take time and money to deploy.

It should be noted that ammonia, hydrogen, and gasoline have all been assessed as having roughly equal overall safety.  Ammonia’s higher toxicity is offset by very low fire and explosion risk.

As to why ammonia cars are lagging behind hydrogen cars?  I don’t think they are in reality, in spite of the H2-hype.  Ammonia ICE cars are much closer to what we build today than fuel cells.

Bob Meinetz's picture
Bob Meinetz on November 16, 2015

Nathan, it seems to that by the time we could establish an ammonia infrastructure battery tech will have improved to the point where range and recharging time are no longer significant issues for EVs.

I think ammonia suffers from the same chicken-egg problem as hydrogen, although less so: refueling infrastructure won’t happen without vehicles, and vice versa. Joe Romm estimated the cost of a H2 infrastructure at 1/2 $trillion; even if ammonia were to come to half of that, I don’t know from where the momentum would come to get the job done.

I’d love to be proven wrong. A President Sanders might be able to pull it off, but what a fight it would be.

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