What is waste incineration?

The United Kingdom generates an enormous amount of waste and the space of landfill sites is running out. The best solution? This would be to recycle as much of the waste as possible but instead incinerators are burning the waste. In some cases, the electricity is being generated to produce electricity yet this does not seem to work very well as people are becoming concerned that this incinerator idea is emitting too many harmful gases which does not produce the notion of "green energy".