A few weeks ago, 100-foot-wide (30.5-metre) propellers began turning on the recently completed World Trade Center building, making Bahrain home to the world's first building-integrated wind turbine skyscraper. The building includes two sail-shaped towers that climb 54 floors above the beachfront site. Three small bridges link the towers, with a massive wind turbine hanging from each. The towers funnel the ocean winds into the turbines, which generate more than 10 per cent of the energy used by the building.

As climate change and renewable-energy policies level the playing field in the energy industry, alternative-energy companies are racing to assure investors, policymakers and the public that they can scale to meet the needs of energy-starved consumers. During the last few years, a clutch of clean energy projects have emerged on a scale never seen before. Forbes.com has identified the biggest and boldest projects among them.

We surveyed the clean energy landscape for new and recently completed projects in solar, wind, geothermal and wave energy that produced the most grid-connected electricity. Forbes.com also identified the green government initiative and green building project with the highest estimated dollar value. The results are different from what most people would expect.