Posted on 02/07/2003 7:31:16 AM PST by Isara
When your hydrogen scam can do that, it won't be a scam.
The key to hydrogen isn't fuel cells or hydrogen, but cheap nuclear power.
By the way, is there any use of CO? It's toxic to human.
Of course there is not a infinite supply of fossil fuels on the planet. But as a practical matter, we will never run out of any fossil fuel.
Of course not--but by getting the fuel into a source that can be used directly in fuel cells, the MUCH higher conversion efficiency of the fuel cell more than compensates for those losses. It is the efficiency of the TOTAL CYCLE that counts---not just the efficiency of the gasification process vs. combustion.
And in fact, for central power usage, coal gasification/fuel cells is an even BETTER combination, as what is called the "solid oxide fuel cell" can eat BOTH the hydrogen AND the carbon monoxide.
It is the use of the fuel cell in the total conversion process that makes major gains in efficiency possible.
Yes--the carbon monoxide is itself a fuel. Burning it with more oxygen converts it to carbon dioxide, and the energy from it can be "harvested" to fed back as steam or electricity to help drive the conversion process. Some fuel cells will run directly on gasification syngas---converting both the carbon monoxide AND the hydrogen into electricity.
How big will the fuel cells be? We are talking about burning coal, saparating CO and H2, burning CO and combining H2 with O2.
I can see why you chose your screen name. Never is a long time.
Size of the individual fuel cell stacks won't be very large, but for a directly-coupled gasification-fuel-cell-gas-turbine combined cycle power station, there will be quite a few of them. With the solid oxide fuel cells, the only separation that needs to be done is to be sure the syngas has all the particulate matter knocked down, and probably scrubbed to remove sulfur-compounds --- then the mixed CO and hydrogen will be sent directly to the fuel cell to generate DC electric power. The "combination with oxygen" takes place in the fuel cell itself.
Yep, that's called "energy conversion inefficiencies".
Gee, Willie--what a TRULY intelligent and insightful comment. You could have farted and contributed equally to the discussion.
And the methane produced would've had more energy than an equal volume of hydrogen at the same pressure and temperature.
When the cost of fossil fuels exceeds the cost of the alternative fuels, the replacement of fossil fuels will occur. At that time we will still have considerable reserves of all types of fossil fuels still remaining in the ground, undisturbed.
Which leads me back to the stark truth of my original response, "we will never run out of any fossil fuels."
Most of it will come from natural gas.
I understand the advantage in the fuel cell replacement of the IC. It avoids the combustion step at the end use and that has environmental advantages, as its probably better to deal with fog than smog. But surely the gasification process is not without its share of effluents. You mentioned the slag. I'm wondering if airborne releases also occur. In conventional refining there is always some waste gas produced that is flared off. I've been around some refineries that were pretty smelly. Would a coal gasification plant present a similar environmental impact?
Again, I'm just running down the questions that might arise if a national effort were made in this direction. Trading impacts from oil refineries for those from gasification may not be a bad bargain if it helps us in other ways, like reduced dependence on imported energy, or more economical fuels.
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