Think wind power is better for the earth than shale oil? Consider the following information Alex Adrianson highlights for the Heritage Foundation’s “Insider Online” blog.

Wind Power Needs 725 Times More Land to Produce the Same Energy as Shale Oil

A solar park, meanwhile, requires 461 times more land than a fracking site. These figures come from David MacKay, a professor of engineering at Cambridge, who has compared the footprints of wind, solar, and shale energy:

When you consider all the impacts, it’s not clear why some energy sources should be considered green energy and other sources dirty. As McKay concludes: “[T]here is no silver bullet ­– no energy source with all-round small environmental impact. If society wants to use energy, it must get its energy from somewhere, and all sources have their costs and risks.”