Wind is inherently variable, so it can never compete with the cheap and dirty coal that generates half of America's electricity.

风一向多变，因此它永远比不上廉价又脏兮兮的煤，后者产出了美国半数电力。

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By quickly storing and delivering charge, batteries could accommodate fluctuations in supply and demand, and help to incorporate variable sources of power such as wind and solar.

通过快速的存储和高效率的充电模式，电池可以很快的调节供应和需求之间的平衡，同时又可以吸收其他多变的能源，例如风能和太阳能。

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Wind and solar energy are variable by nature: the sun doesn't always shine, and the wind doesn't always blow.

风能和太阳能随大自然而变化：太阳并不是总有光芒，风不是一直在吹。

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Dorothy Thompson, chief executive of Drax, told BBC News that biomass was the ideal fuel to balance variable wind power.

BBC: Biomass may hinder climate fight

Today, however, the dominant wind is reported to have shifted and wind direction is more variable.

UNESCO: Social and Human Sciences

The NGIPS platform is critical for clean energy, especially variable resources like wind power and solar photovoltaics.

FORBES: Microgrids: Ten Clean Technologies Needed to Win the Next Naval War