Read the text and choose the best options to fill in

Read the text and choose the best options to fill in the gaps.
Every day you can see the wind blowing and watch all of that wasted energy just floating away. A lot of energy is thought to be (1) ... and all you need to use it are a few wind turbines! Currently less than 1% of the Earths energy needs are (2) ... by wind, with Denmark being the most wind-friendly producing 23% of its own energy needs from wind. The energy produced is totally clean and also one of the (3) ... around and it is able to produce (4) ... 18 times more energy than is consumed in its construction, (5) ... nuclear which is estimated at around five. People are often worried about the look of wind farms but what they often forget is that the land can still (6) ... for farming, with only 1% of the space being taken up by the wind turbines. One of the biggest (7) ... about wind turbines, is their effect on bats and birds. In Norway, nine out of ten sea eagles were killed by turbines. Bats too are a serious problem. Even the manufacturers of wind turbines are (8) ... concerned by the numbers of bats being killed, prompting ongoing research.