Intel is the world's biggest microchip-maker with $55.9bn in 2014 sales. It is also the largest US corporate voluntary buyer of green energy – as opposed to utilities having to comply with state mandates.

The Santa Clara, California-based company was one of the 12 initial signatories of the Corporate Renewable Energy Buyers Principles last year.

The renewable power Intel buys is used to run its manufacturing plants in states including Oregon, Arizona and New Mexico.

Marty