by TheAntiDoomer » Fri 21 Jan 2011, 13:40:58
$this->bbcode_second_pass_quote('mos6507', 'F')ossil fuels are stored photosynthesis. Any solar-based process, whether biofuels or splitting water into hydrogen or what not, is ultimately limited by the maximum energy potential of immediate sunlight, not the stored sunlight of fossil fuels.
We're already tying up a large percentage of that solar potential through agriculture, and what we're not tying up through agriculture probably needs to be left alone for a functional biosphere. So there's a limit to how much sunlight we can redirect for fuel production.
As such, no solar process, even if it were 100% efficient, could ever replace what fossil fuels do for us.
Not to say these developments are useless. We'll certainly take what we can get, but the rhetoric, which either implies or directly states that these things could be drop-in replacements for fossil fuels, is seriously flawed.
I really don't buy all those stories that say we could run the planet on the land area of greater houston or something. The math behind that stuff is really off.
This is probably why Lovelock is gangbusters for nukes, because it's the only real step up from fossil fuels in energy density. Either we perfect nukes or we do some serious powerdown, but I really don't think we can have a modern ecotopia off renewables.
Mos, let's do the math shall we?
One acre of land of land has the potential of 7.26 megawatts per day x365 = 2646 megawatst per year = 8805 Gigajoules per year
One barrel of oil contains about 6.1 Gigajoules
8805/6.1 = about 1440 Barrels of oil Equivalent potential, so to get their number for 800 barrels of oil per acre, it looks like they would have to be somewhere around 50% efficient.
So in summary Mos the numbers do they the Potential energy to produce 800 barrels of oil as they claim is there.