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Hydrogen vehicles aren't too eco-friendly in terms of carbon emissions, according to an in-depth new study.  (Source: Web Wombat)
Study indicates plug-ins feature a lower emissions life than gas vehicles, but hydrogen vehicles feature greater emissions

The hydrogen vehicle movement appears stalled.  The push to use the diatomic gas as auto fuel never exactly made it off the ground due to a lack of infrastructure -- production, distribution, and storage facilities.  However, for a time automakers like Toyota and Honda were pushing ahead with testing of hydrogen fuel cell vehicles. 

Even this year, news leaked that GM was considering launching a commercial fuel cell vehicle in 2015, despite lack of support for the hydrogen movement from U.S. President Barack Obama.  However, of late, the big automakers like Toyota and Honda have backed off the effort to push hydrogen vehicles onto the market.

A new study might put another road block in front of the prospect of a near term commercial hydrogen vehicle release, while giving the plug-in vehicle movement a nice boost.  The study was authored by Ryan McCarthy at the University of California, Davis and published in the Journal of Power Sources. The ground-breaking study, entitled "Determining marginal electricity for near-term plug-in and fuel cell vehicle demands in California: Impacts on vehicle greenhouse gas emissions", examines the emissions impact of hydrogen and plug-in vehicles versus their gas counterparts.

Lowering carbon emissions to fight warming, along with high fuel prices and global-political instability, has been a key driving factor for the adoption of hybrids and alternative fuels.  The new study, though, judged hydrogen vehicles to be an utter failure at that objective, in their current state.  The study concluded, "All of the pathways except for [fuel cell vehicles] using hydrogen from electrolysis reduce [greenhouse gas] emissions compared to ICEs and [hybrid electric vehicles]."

It doesn't dissuade further research into hydrogen vehicles; it simply indicates they are unlikely to be ready for showtime anytime soon.  It points out that steam methane reforming is a promising emerging method of hydrogen production that may one day allow hydrogen driven vehicles to actually live up to their emissions promises.

In the near term, the study finds that plug-in electric vehicles are the best option in terms of lowering carbon emissions.  Despite using electricity mostly generated by "relatively inefficient steam- and combustion-turbine plants" the well-to-wheel carbon impact of EVs is still significantly lower than hybrids.

While by no means the definitive study on the topic, the new work does much to fill in the gap in knowledge about what exactly the true impact of green vehicles are.  While the topic of on-the-road emissions has been well researched, there's been much less progress in examining the full lifetime impact of vehicles.  Now, that lifecycle has been examined in depth and EV advocates can put another feather in their caps, while hydrogen advocates are once again handed another setback.

The study may play a crucial role in forming the policy of California's Low Carbon Fuel Standard, an effort to reduce the carbon impact of transportation.  And given that President Barack Obama's Environmental Protection Agency has embraced California's emissions policy, the new study could have a profound impact on the course of regulations and the auto market nationally, as well.



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RE: I might care
By Solandri on 1/1/2010 1:22:09 AM , Rating: 3
quote:
For instance a smallish solar array producing power for the newer types of hydrolysis could easily produce enough Hydrogen to run a couple of vehicles and power for a well designed modern home

The average American car is driven about 12,000 miles a year, which works out to 32 miles a day (ignore that they're not driven every day). The Chevy Volt can travel 40 miles on 8 kWh of electricity, or 32 miles on 6.4 kWh.

Sunlight hitting the Earth's surface normal to a panel delivers about 800 Watts per square meter.
Factor in 15% efficiency (about what the best commercial grade panels right now can deliver).
Factor in 12 hours of night.
Assume 250 sunny days out of the year (the rest rainy or cloudy).
Assume the panels are tilted at your latitude to maximize exposure.
Factor in pi/4 for movement of the sun during the day.
And you get an average of 32.3 Watts per square meter of panel throughout the year.

To build up 6.4 kWh in a 24 hour period, you'd need about 8.3 square meters of panels just to allow one car to travel only 32 miles per day. In practical use, you'll need even more panels because I didn't account for cars being driven more miles on workdays, nor the efficiency losses of adding a hydrolysis step.. This is not a "smallish solar array" and unless our sun goes nova it never will be.

Solar energy is plentiful, but it's very sparse. It's very useful for low power and static applications, but that's about it. Energy-intensive applications like transportation and manufacturing are going to need to get their power elsewhere. The people who believe solar power will somehow provide all our energy needs are just as deluded as the folks who completely deny any correlation between CO2 and temperature. They need to stop believing in pipe dreams and actually grind some numbers to see exactly what is and isn't possible with solar.

Given the limitations of current and probably next- 25-years solar tech, IMHO the best way to capture solar power is to let plants do the capturing for us. They are self-replicating and manufacture their own solar panels called leaves. Then either burn the cellulose they produce, or convert it into some alcohol-based fuel. If we are going to go pure solar, there's going to have to be a huge breakthrough in solar concentrators. There's no way to get around the surface area requirements, but a concentrator can make that surface area a lot cheaper to cover.


RE: I might care
By dnd728 on 1/1/2010 8:57:56 AM , Rating: 2
There's an interesting concentrator - http://www.businessweek.com/globalbiz/content/mar2...
but it gives quite a lot of its energy yield in the form of heated water.


RE: I might care
By Hoser McMoose on 1/2/2010 10:21:57 AM , Rating: 2
quote:
There's an interesting concentrator

Concentrators do virtually nothing to change the calculations above. The amount of energy coming from the sun is still the same, it's just that now your space required is determined by the size of your concentrator vs. the size of your panel itself.

Basically a solar concentrator is a method of reducing the cost, not the size, of a solar power setup. This can indirectly allow you to increase the efficiency of your solar power setup by using a small amount of more efficient PV cells, but you're still probably looking at less than 20% efficiency in converting solar energy to electricity.

Now, getting hot water from the sun, in a climate like Israel in particular, is a whole lot easier.


RE: I might care
By dnd728 on 1/6/2010 8:15:52 AM , Rating: 2
"The first generation of our technology should be capable of harnessing about 70% of the solar energy that hits the dish to produce electricity and thermal heat," says Faiman.


RE: I might care
By Hoser McMoose on 1/2/2010 9:53:38 AM , Rating: 2
quote:
Factor in 15% efficiency (about what the best commercial grade panels right now can deliver).

If your goal is simply to produce hydrogen you can actually do somewhat better than this by using a photo-catalytic cell rather than a photo-voltaic cell and then hydrolysis. Basically you want to skip the middle-step of generating electricity, just put water in, get hydrogen and oxygen out.

Unfortunately "somewhat better" ends up translating to about 20% efficiency vs. about 9% efficiency in your example (hydrolysis is only, at best, about 60% efficient, so 15% x 60% = 9% overall), so in the end it doesn't change your numbers much. What's worse you also need to factor in the loses in converting hydrogen back to electricity in your fuel cell, currently only about 50% efficient with hopes that it MIGHT hit 70% in the future.

You're still probably much better off with simply sticking some PV panels on your roof and using their to supplant some demand from the electrical grid and getting a plug-in hybrid. When land use is a sunk cost (as it is on the roof of a house) solar power can be a reasonably price-competitive alternative to other forms of electricity generation on small scales at least. You probably won't be *directly* powering your car from solar (especially since it's best to plug in your car overnight) but indirectly you'll at least offset a good chunk of the power use.


RE: I might care
By lco45 on 1/3/2010 7:38:57 PM , Rating: 2
So for the cost of a 3m x 3m solar panel you get:
1. Free fuel for 20 years.
2. No particulates and carbon monoxide in the cities.
3. Stop funding hostile countries.
4. Reduce the chance of global warming.
5. No longer need to rely on ever-changing gas prices.

Let's get started, sounds like a great solution.

Luke


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