The God Species_ How the Planet Can Survive the Age of Humans - Mark Lynas [70]
Solar thermal plants—which concentrate the sun’s heat directly to drive a central steam turbine generator—will use a lot of land because they need thousands of mirrors to be sited in the same place. This may not matter much in the northern Sahara, where the biodiversity impacts of massive-scale solar deployment are likely to be minimal in the hyper-arid desert. But in the U.S. southwest, conflicts are already appearing between solar enthusiasts and conservationists. On December 30, 2010, the Sierra Club filed a suit with the California Supreme Court to stop a massive solar plant going ahead in pristine habitat in the Mojave Desert, claiming that threatened species like the desert tortoise, Mojave fringe-toed lizard, and even the golden eagle would be harmed.48 Earlier the same month, a coalition of Native American and civic groups filed a legal suit against the U.S. Department of the Interior regarding six different solar thermal projects, aiming to save not only desert habitat but also cultural landmarks important to the tribes. Here I would side with the conservationists. The Mojave Desert is one of the great wildernesses mentioned earlier in this chapter, and is particularly fragile given its location near massive population centers in the highly developed U.S. Southwest. It should be properly protected as important wildlife habitat against all forms of development—renewable energy included.
The issue is a classic illustration of the challenges that climate change mitigation will throw up regarding land use—the biggest of which is the danger of what a group of U.S. conservation experts term “energy sprawl.” The conservationists, working with the American group The Nature Conservancy, have quantified the energy-sprawl implications of different low-carbon technologies, and their results make challenging reading.49 Supporting what I argued earlier, biofuels come out worst by an enormous margin, gobbling up 300–600 square kilometers per terawatt-hour of electricity produced each year. At the other end of the scale, nuclear is least land-intensive with only around 2 square kilometers affected to produce the same amount of power. Renewables are in the middle, with solar thermal needing 15 square kilometers, solar PV (on open land rather than on buildings) 36 km2, and wind 72 km2.
Luckily there are many ways that the land-use intensity of renewables can be reduced. As I have already pointed out, solar PV can be mounted on existing buildings and other developments. For wind, the obvious solution to the land-use conflicts of “energy sprawl” is to base most of the industry offshore. The further offshore the better: while studies have found habitat-reduction impacts on ducks and other seabirds for shallow-water turbines, there are many fewer species farther away from the coast.50 Technologies are already being developed for deep-sea floating turbines, with each windmill potentially delivering as much as 10 megawatts of power—enough to provide electricity to several thousand average Western households.
In the shorter term, countries with large areas of shallow continental shelf are building large offshore wind parks with turbines anchored to the seabed. For the U.K. much of the North Sea is available for wind development, and the country is already leading the world in offshore wind deployment—the theoretical ultimate resource potential is many times Britain’s total current electricity consumption. With its windy coasts, the Scottish government in September 2010 announced an impressive target of becoming 80 percent renewable within the next decade.51 In Europe things are moving fast: In December 2010 ten European countries signed an agreement to develop an offshore electricity grid in the North Sea, the first stage in a continent-wide “supergrid” that will be necessary to balance out the intermittency of renewables