net energy gain

基本解释

Furthermore, ethanol requires a tremendous amount of fossil fuels to produce. The net energy gain is not terribly high.
此外乙醇的制造得耗用大量石化燃料，两相抵扣之后、我们最后得到的乾净能源量其实并没那麽高。
Energy efficiency(net energy gain or energy ratio) of corn-based ethanol as a substitute for fossil fuel is an important criteria for assessing its sustainability.
玉米燃料乙醇作为化石燃料的替代品，能量效率（净能量或能量比）是评价其可持续性的一个重要标准。

So we can compare the two electron configurations, and we can actually think about what we figure out from them, we see that two are lowered in energy, two electrons are raised in energy, so we have no net gain or no net loss in energy for h e 2.
我们可以比较两种电子构型，我们可以考虑,我们发现这，两个电子能量变低，两个电子能量升高，所以在He2里没有净的能量得失。
麻省理工公开课 - 化学原理课程节选

This results in an energy efficiency of more than 100 percent — a net energy gain.
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