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Q & AJune 30, 2008Penn State's Craig Grimes(page 2 of 3)ERN: What is the best-case scenario in terms of cost and capacity for generating hydrogen by solar water splitting? CG: Someone comes upon the right material architecture to provide us something that doesn't cost much (plentiful), is impervious to photocorrosion, and converts sunlight to hydrogen (or alternative chemical fuel) with a photoconversion rate of about 30%. I think this is possible, but its a very hard problem and not one likely to be solved without application of considerable resources. ERN: Will solar water splitting ever be able to provide hydrogen on demand, or will we have to separately solve the hydrogen storage problem to take advantage of sun-generated hydrogen? CG: Depends upon the application. A few photoconversion panels on the roof of a SUV won't get you very far. However, one-third of the earth is desert. It would be nice to use these lands for something, maybe something like generating energy. Yes, there are problems with hydrogen storage. Nothing compares with finding a huge lake of oil, free for the pumping! Too bad these lakes of oil are finite and burning the oil has rather negative consequences. It's hard to beat something that is more or less free, relatively safe to use, and provides 121.8 megajoules per gallon. 121.8 megajoules per gallon! An average person can generate about 80 watts over a sustained period, run the math per people equivalents. ERN: What is the math? CG: 121.8 megajoules = 17.5 80-watt people working for 24 hours per the equivalency of a gallon of gas. If you think how far your car can go on a gallon of gas, and how long it would take a cluster of people to push it that far, the numbers come out about the same. ERN: This brings up the question of liquid hydrogen versus gas hydrogen. How much energy does it take to liquefy hydrogen, and is storing hydrogen in liquid form worth it? CG: Depends, we'll have to work it out. I think we may all use propane-tank like cylinders and go with that. Fuel cells might work, so we might be able to put the H2 into fuel cells (but we have a long ways to go for this vision to become reality). ERN: Is the hydrogen economy feasible, and if not, what place will hydrogen have in the energy mix of the future? CG: It's feasible, but not free. While we are used to spending vast fortunes on this war or the other, we are not used to spending money on energy since it has been more or less free since 1900 or so. Still, for all the hoopla of $4/gallon gas the amount of annual federal spending on developing new solar energy technologies is equal to about what a professional baseball player makes. And there you have it. We have built a society predicated upon, in essence, free energy. We don't need slaves or farm animals anymore since we have petroleum. However since nothing that we know of is so energy dense and stable, and more or less free, as petroleum, what replaces it will most likely be a mixture of this and that chosen for the specific application. ERN: What is the actual amount of federal spending on new solar energy technologies? CG: Let me put it this way, an elevated local highway interchange (I99 and US322) was built here a few years ago for $160 million dollars, an amount that significantly exceeded NREL's [National Renewable Energy Laboratory] annual budget -- at least then, and may still although the food-to-fuel dollars might have changed the dollar totals. [Ed. note: NREL's budget is about $235 million.] ERN: Photovoltaics research is proceeding along several avenues: dye-sensitized, organic semiconductor, thin-film, multijunction and variations of these involving nanotechnology. What is the state of photovoltaics research, and where would you place your bets? CG: Today the PV market is almost entirely silicon. Can we do better in terms of cost and efficiciencies? I certainly hope so, but here it becomes a multi-variable drama and what comes out is anyone's guess. ERN: Concentrated solar power systems, which focus sunlight to generate heat to drive mechanical electricity generators, are emerging as a relatively cost-effective method of producing electricity from sunlight. What role will these systems play in large-scale power generation? CG: It's a great idea and approach. One just needs cost effective materials able to withstand high temperatures without degradation. Buying expensive ceramic materials for fighter jets engines is fine with DoD [Department of Defense] budgets, but may be challenging per a production scale commercial product. ERN: Is the government's goal of achieving grid parity -- making solar electricity price-competitive with traditional sources of electricity like coal-fired power plants -- by 2015 realistic? CG: It's not going to happen unless we do something besides talk, and it's not going to happen without government intervention, e.g. a tax on CO2 emissions and $ incentives to develop, sell and buy solar cell technology. Japan and the European Union have active financial support systems in place to encourage use of solar energy. They are the leaders. single page | < previous 1 2 3 next > Back to ERN June 30, 2008 |
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