NER 300 is one of the world's largest funding programmes for innovative low-carbon energy demonstration projects. The programme is conceived as a catalyst for the demonstration of environmentally safe carbon capture and storage and innovative renewable energy technologies on a commercial scale within the European Union. The programme is managed by the European Commission.

The NER 300 programme took its name from the sale of 300 million emission allowances from the New Entrants' Reserve (NER) set up for the third phase of the EU emissions trading system (EU ETS). The funds from the sales have been distributed to projects selected through two rounds of calls for proposals, covering 200 and 100 million allowances respectively.

The programme funds 39 projects in various technology categories (bioenergy, concentrated solar power, geothermal, ocean, smart grids, photovoltaics, wind, and carbon capture and storage).