Deriving fuel from trees costs more than wind and solar power and it emits more carbon than coal. There are many heated debates about this kind of energy, known as forest or woody biomass.
The pioneering legislation is ten years old – and the latest science means it now does not go far enough.
Greater Manchester wants to be "zero carbon". But this sort of target raises some important questions.
Cities all over the world are facing growing challenges to provide clean, reliable water. And many of the fixes, such as desalination plants, have a huge carbon footprint.
As part of its 100-day priority plan, New Zealand's new government has pledged to set a target of carbon neutrality by 2050, which means phasing out fossil fuels and products that burn them.
A new analysis by ClimateWorks Australia says that the electricity sector needs to do far more to cut its carbon emissions than will be delivered by current policies.
The University of California intends to be carbon-neutral by 2025 by implementing existing technologies and focusing on public education. Is this a model for decarbonizing at large scale?