By Liezel Hill, Bloomberg Business.

BMW AG’s car-assembly plant in South Africa is doing its bit to help the German carmaker edge toward a global target to supply all its production with renewable energy: It’s getting some of its power from cow manure.

The company has agreed to a 10-year deal to buy as much as 4.4 megawatts of electricity from a biogas plant about 80 kilometers (50 miles) from its factory north-west of Pretoria, the South African capital. Surrounded by land where about 30,000 cattle graze, the operation runs off gas emitted by a fetid mixture of dung and organic waste ranging from sour yogurt to discarded dog food.