In addition to low emissions, natural gas can also be used as a petroleum fuelsubstitute or extender as in the case of dual fuel engines.
除排放低外，天然气可以替代石油燃料，或作为双燃料发动机的混合添加物。
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The increasing use of dried animal waste as a substitutefuel has also hurt the soil because this valuable soil conditioner and source of plant nutrients is no longer being returned to the land.
The sea water appears to have been brought in as a substitute for the regular water used as coolant for the uranium fuel rods at the heart of the reactor.