4 posts • joined Friday 11th May 2007 20:33 GMT
Amen to that -- invest in Earth!
Space travel is fine to write about and make movies about, but when it comes to investing untold billions what exactly are we trying to achieve? As for colonization of the universe, forget it. Anywhere we go we have to bring more of Earth with us than most people realize -- and it's not just the basics like food, water, radiation shielding, gravity -- all hard enough on their own to bring along. There's a significant psychological component too. Nobody really knows how the human brain would work when separated from Earth for years. I wouldn't be surprised if it made most people psychotic, or at least severely depressed -- just sitting in a windowless room for a few days can do that. Even if Earth-like planets exist a few light years away there's no plausible technology that could get human beings there. The bottom line is that we are part of Earth. We deceive ourselves if we pretend we can exist without it. Our ties to our planet are deeper than anyone knows. Plus the shear magnitude of the expense of trying to leave Earth in any significant way are better spent making our one true home more livable. Let's keep our priorities straight.
biofuels are carbon-neutral and hydrogen isn't a fuel
Hey John Gross,
There isn't any unbound hydrogen -- you have to break water or hydrocarbons to get it -- and you get out less energy than you put in to break it. That means you have to generate that energy using renewables if you want to be carbon neutral. So having a good carbon-neutral power source is a necessary input to a proper hydrogen system. A better way to think of hydrogen is as a battery. Let's stop thinking about hydrogen as a panacea and focus on reasonable ways to produce electricity, which would be needed for water hydrolysis. There are only a few ways we know how to make electricity without carbon emissions: 1) solar, 2) wind, 3) hydro (damming rivers), and 3) nuclear.
What's wrong with these? There's too little energy per square meter in solar. The wind doesn't blow fast or steady enough near the ground and you need a lot of space. Dams kill river ecosystems. And nuclear reactors make a lot of nasty waste that we don't know what to do with, although France does a pretty good job of minimizing that with breeder reactors, but then you have that weapons-grade plutonium to deal with...
Biofuels are theoretically carbon-neutral because growing the plants absorbs the same amount of carbon dioxide that is released when they are processed and burned. But the land use issue still remains.
All options are bad, unfortunately. I like nuclear because the negative results can theoretically be contained, and it's the only option that can pretty easily replace our existing petroleum system with existing technology. Everything else requires too many other changes throughout the economy.
I said unbound hydrogen. Sure, hydrogen may be the most abundant element in the universe, but here on earth it's all locked up in things like water. There's plenty of it, but it costs more energy to unbind it from water molecules than you get out of it -- not much of a fuel in my opinion. Calling it a fuel makes it seem like an alternative to other power generation methods - which it is not. It's an intermediary - a battery - nothing more.
Hydrogen isn't really a fuel
Unbound hydrogen doesn't exist in nature in any significant quanitity, so the question arises, "where are you going to get it?" It takes more energy to separate hydrogen from water or hydrocarbons than you get back by using it in a fuel cell, so it's inherently not a way to generate power. It is, however, a pretty good way to store power. Using power generated from some other fuel, like natural gas, wind, solar, nuclear or whatever, can be used to split water and thus store some of that power for later. Fuel cells are better thought of as efficient batteries than some kind of replacement for a power generator. Hydrogen is not a fuel, and fuel cells don't generate power. Let's not forget that. If you want to replace crude oil as a vehicle fuel you need to think about actual fuels - like those mentioned above. Hydrogen and fuel cells can play a role, but only as an efficient battery technology to make electric cars possible. An extremely high capacity lithium-ion battery would be just as useful as a fuel cell for displacing oil, and probably cheaper.
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