Owl Power Company manufactures the Vegawatt, a machine that converts restaurants' waste vegetable oil to energy. It consists of a diesel engine that drives a generator to produce electricity and a system to extract heat to produce hot water for use at the restaurant. It is optimized for restaurants with 3-5 deep fat fryers The great beauty of this machine is that it turns a waste product into a valuable resource. It typically takes about two years for an American installation to pay for itself. Moreover, the power is carbon-neutral.
So, if you have a restaurant with deep fat fryers, you should buy a unit (or more, I'm not sure how it would work at a large facility). Your investment will pay for itself quickly and continue to reduce your utility bills and increase your profits. It won't eliminate your need for external, but will reduce it noticeably.
I think it would be great if large chains bought these. The lower-end ones like McDonalds are doing well during this recession, so they have the cash to buy these. As production ramps up, their prices should fall, making them even more profitable to use.