useful energy

基本解释

Getting useful energy from formate is now the simplest way known for any life form to get its fuel, though it relies on the absence of oxygen.
从甲酸盐中获取所需的能量是目前最简单的维持生命方式，虽然它依赖于无氧的环境。
To generate useful energy, plants have evolved very sophisticated "nano-machinery" which operates with light as its energy source and gives a perfect quantum yield of 100%.
为了产生有效能，植物进化出了异常精密的“纳米机器”，它以光为能量来源，光能转化率达到了完美的100％。
The building of a real-life version of "Maxwell's demon" – which can turn information into useful energy – might mean that future nanomachines can be powered purely by information.
建造“麦斯威尔妖”的现实生活版本——它可以把信息转变为有用的能量——意味着未来的毫微级计算机可能纯粹地依靠信息来作为动力。

So, in this class we'll be talking about energy a lot, and it's often useful to draw some sort of energy diagram to visualize the differences in energy that we're discussing.
所以，这堂课我们会讨论很多,关于能量的问题，讨论时，画能级图来使能量差别,形象化常常是很有用的。
麻省理工公开课 - 化学原理课程节选
Now these quantities were useful because you could relate them. The slope of changes, with respect to volume or temperature of the energy with respect to quantities that you understood, that you could measure.
去得到这些量,这些量很有用，而且你们已经知道了，怎么把它们相互联系起来,像这种比例形式的量，能量比上温度或体,或其它你们懂的可以测量量。
麻省理工公开课 - 热力学与动力学课程节选

Think of nuclear fission: it generates useful energy but if it runs out of control you get a cataclysmic explosion.
ECONOMIST: Why Germany seems not to want a quick fix for the euro crisis
Dr Kanatzidis argues that wherever heat is generated as part of power generation, thermoelectric devices could help extract more useful energy.
ECONOMIST: Thermoelectrics