It really irritates me when "environmentalists" speak out against technologies that reduce greenhouse gas emissions. It seems like some people think we should just all stay in bed all day, instead of workout ways of doing what we do in better ways.
Today, for example, Virgin Airlines proved that it's possible to fly an airliner using 20% biofuels. Now, the flight itself didn't do that, as only one engine was using the biofuel mix. It's also true that biofuels don't have zero emissions, so the real saving on this flight was quite small. But, it's important to demonstrate the possibilities.
Biofuels are getting bad press from some quarters right now, because (a) they use a lot of land, and (b) farming biofuels uses a lot of fossil fuels. Of course, all those fossil fuels could be replaced with biofuels - at the price of using more land of course.
But, there's good news in PNAS, and in Scientific American this month. Switchgrass, which is a native North American perennial, can produce five times as much energy per hectare than maize, and reduce greenhouse gas emissions by 94% compared with fossil fuels. Perennials are also much better for soil condition, And, the root systems become extensive thereby locking CO2 into the soil. Switchgrass requires less fertilizer (remember, organic fertilizer production requires lots of land) and less irrigation than maize.
Now, that 94% figure is from a full lifecycle analysis, and hammers any claim that biofuels don't really save CO2 emissions. It doesn't, though, address the land use problem. However, my view is that this just means that we really need to work out how we're going to use land in the future. Most agricultural land, for example, is used to grown meat and dairy products for the developed world. There is some spare agricultural land, that's currently not in use. However, all the remaining productive land is forest, and it would be insane to cut that down in an attempt to save CO2 emissions.
Maybe we should only let vegetarians fly!