Very nice concept but would you really want to turn the US auto fleet into a hydrogen-fueled one?

My understanding is that there are only two feasible sources of hydrogen: electrolysis of water, which requires a lot of electricity, or stripping the H from methane/natural gas (CH4), which uses up a scarce fossil fuel resource.

If you go the first route, you could have homeowners stripping water into its constituent elements using solar arrays on the roof. But I'd bet it would take many, many days of photovoltaic use from an average solar array on an average house on an average day to get enough hydrogen to fuel the car.

If you went the other route, and used nukes working on their off hours to perform electrolysis, you could produce huge amounts of hydrogen. But then you have the problem of how to distribute it. My understanding is that hydrogen can't be moved through steel pipes, and it requires several multiples of volume to store an equivalent amount of energy compared to existing gas stations. So an awful lot of deliveries would have to be made to the still unbuilt network of hydrogen stations. It's true that California has some hydrogen stations. As far as I know, there is only one hydrogen station on the east coast. It is located in a Potemkin Village gas station near the US Capitol.

The most recent cost estimates I've seen suggest that hydrogen would cost on the order of at least $8 for the equivalent of a gallon of gas. This may be incorrect, but I know it would be very expensive.

But the most serious issue is, can we afford a hydrogen-fueled fleet competing with a plug-in hybrid fleet? Both will require truly massive infrastructure investments and it is not clear, just at the moment, that we could afford even one of them.

Natural gas is the most readily available solution but solar catalysis or biogenesis are more likely long term. The problem with hydrogen as with any gas is storage, a problem comparable in difficulty to batteries. Using aluminium for energy storage to produce hydrogen on demand may be the simpler model.

I've been using public transport this summer and have gotten by on about $60 worth of gasoline during the previous two months (including a weekend vacation that required an auto). Plus I've been walking a lot more, resulting in positive health trends.

Hi Andrew,
I believe hydrogen is rubbish as a fuel source for cars or in general as there are better options. It is not an energy source, it is an energy carrier. The nonsense about cars like the one you talk about above being zero emission is akin to . It is not zero emission as you have to consider the energy that went into making the hydrogen, which led to emissions. The difference between petrol/diesel and hydrogen is that the main emission for petrol/diesel comes when you burn it, whereas for hydrogen it comes from producing it. It is not that energy intensive (compared to hydrogen) to extract and refine oil.

There are 2 main problems with hydrogen production:
1) The cheapest ways to produce hydrogen (splitting NH4 or methane) require more energy than you get back. It is more efficient just to burn the methane/use the NH4. This is related to calling hydrogen an energy carrier not an energy source. It is just carrying the energy from the methane in another form, i.e. H2.

2) Hydrogen developed from renewable resources, such as from renewable energy via hydrolysis or algae hydrogen production are too costly and inefficient sicale wise. By this I mean if you covered your house in panels you still would not be able to produce enough hydrogen to really do anything. The same for algal production. It requires too large an area for trapping H2, hurting efficiency, and would be insanely expensive.

This doesn't even consider storage and transport of hydrogen which require large amounts of eneregy to pressurize it into a highly dense energy form.

On top of this using hydrogen as a fuel source has much greater safety issues than normal petrol. Hydrogen burns with an invisible flame and hydrogen cars are basically massive bombs.

There's a reason in scientific circles hydrogen as a fuel source is known as the "hydrogen mirage." It is always 20 years away. I of course believe it's important to fund some research into using hydrogen as a transport fuel as there is upside in it over conventional transport fuels but the challenges faced to get to that point are very difficult to solve.

Hi Andrew,

Your post is timely as there have been a couple of recent advances in the production of hydrogen and hydrogen fuel cells. The August 1 issue of Science summarizes these on page 620. (Sorry I can't link it as I think it requires a subscription).

I certainly agree with some of the points made by your other readers, but I don't think current hurdles to hydrogen use should lead us to dismiss the fuel out of hand. A couple of points:

1. Yes, hydrogen is currently an energy carrier. But that is only because it is produced from other energy sources (mostly fossil fuels) and as such, represents another form of energy from those fuels. From any perspective (environmental, economic, etc.), it is certainly more efficient to simply use those fuels in their natural form.

2. However, using hydrogen in a fuel cell (to produce electricity) produces only heat and water. So, hydrogen is a clean energy source if we can find a natural source of it or produce it without of the use of fossil fuels. This could be done by converting water to hydrogen using solar energy as discussed in the Science article. While this is currently not commercially viable, that doesn't mean that we cannot overcome the technological problems - and the recent work suggests that we might be able to do just that.

3. To your point regarding the use of water: Yes, it is certainly possible that making hydrogen from water would put pressure on freshwater supplies. But it is also true that there would (generally) be no net loss of water since using the hydrogen in a fuel cell would reproduce the water used in its production. Unlike fossil fuels, hydrogen from water could be a renewable fuel (with energy for production coming from the sun...essentially an unlimited resource). This net renewability certainly doesn't remove the problem of regional water conflicts, but this is something that could be addressed with effective public policy. There is also the possibility of producing hydrogen from (the vastly more abundant) seawater (also mentioned in the Science article).

4. Infrastructure: The use of hydrogen as a transportation fuel leads to some serious safety concerns and would require new infrastructure. As such, this may not be the best way to use hydrogen as a fuel, and public investment in such an infrastructure may not be the way to go. An alternative possibility is to use hydrogen fuel cells to power the electrical grid. (This too would require a substantial investment in infrastructure, so the tradeoffs between the two possibilities requires careful study. But we already know that we need substantial investment in our current power grid to prevent future problems). The hydrogen could replace the fossil fuels we currently use in electricity production (mostly coal, which is cheap and abundant but a major source of pollution). The transportation sector could also benefit from this model if the development of electric plug-in vehicles continues to advance. (Currently, I'm not a huge fan of electric cars since it does little to solve our energy problems by displacing our energy use to the fossil fuel powered electric grid).

I don't mean to present these thoughts as a defense of hydrogen fuel. I only want to point out that this is a complex topic with many pros and cons. Like so many policy issues, I don't think presenting it in yes/no and either/or terms does it justice.