CUPERTINO, CA – Apple said it has nearly doubled the number of suppliers using only clean energy in production, including Foxconn, according to reports.

Forty-four companies are now in the program, Apple said, compared to 23 suppliers it disclosed previously.

Last year the company said it uses renewable energy, but a significant portion of its carbon footprint comes from its supply chain.

Apple aims to have suppliers sign power-purchase agreements with new renewable energy projects, and the firm plans to pass its goal of adding 4GW of renewable energy to the grids of its supply chain by 2020.