Because even if, say, offshore wind costs the same as natural gas by 2015 (as predicted by German utility E.ON), there is still an extra cost of building backup power for when the wind doesn't blow.

即便说近海风电成本到2015年(据德国意昂电厂的预测)会与天热气持平，但为了应付没有风的情况，还需建设备份电站，这就会产生额外成本。

youdao

Gas transmission lines carry natural gas from producing areas to city utility companies and other customers.

输气干线管道将天然气从产地输向城市公用事业公司和其它用户。

youdao

Several years ago it acquired Teresen, a natural gas utility in British Columbia which has proved to be highly profitable.

FORBES: A super Canadian stock

Ballard is also developing a power unit with Tokyo Gas, a utility that supplies Japanese homes with natural gas.

ECONOMIST: The dawn of micropower

It could be another natural-gas pipeline or an electric utility, in the U.S. or outside.

FORBES: Buffett To Report Record Quarterly Profit