Finding out whether that's the case often takes years of testing in costly large-scale demonstration plants.

而试图证明这一价值，往往需要在大型示范工厂花费多年时间进行高成本的验证。

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One study found that federal energy-research spending became more productive when it switched from large-scale demonstration projects to lots of smaller-scale technologies.

ECONOMIST: How the government can help things along

In August, China said it would begin developing a large-scale demonstration project in 10 or more cities to put at least 1, 000 hybrid, fuel-cell and all-electric vehicles on the road in each of those cities and provide the necessary infrastructure for the project.

FORBES: Green Business