What is a digital twin? A virtual clone of a real system, such as a factory, a building or a city, which uses data to mirror its current state and behaviour .

The  Paris climate change pact , which  entered into force  last year, was announced with a huge fanfare. The deal aims to limit the rise in average global temperatures to “well below” two degrees Celsius, compared to pre-industrial levels.

It's a brand new sector: the first steps date back to 2012. Today energy crowdfunding is a way of financing solar panel or wind turbine projects.