Apple said on Wednesday that 175 of its suppliers have now committed to using clean energy for the work they do for the iPhone maker, helping to bring more than 9 gigawatts of clean energy on to power grids. The new round of suppliers — which is an increase from the 70 suppliers and about 8 gigawatts of power the company reported last year — are part of the company's efforts to make its sprawling global supply chain carbon-neutral by 2030. The companies must commit to using energy sources such as solar or wind energy for the work they do for Apple, part of the tech company's efforts announced last year for its products to have what it calls a “net-zero” climate impact. Among the suppliers is South Korea's SK Hynix, which supplies memory chips for Apple devices and is one of the first Korean firms to join Apple's programme. Also joining will be Franco-Italian chipmaker STMicroelectronics, a top supplier of sensors and other chips in iPhones that Apple said has started nine new renewable energy projects since committing to the programme. Apple now has suppliers on the programme in 24 countries, including India, Japan and South Korea. “One of the things that comes along with this is building a core of businesses in different markets on different grids who are demanding clean energy. That's helpful to policymakers,” Lisa Jackson, Apple’s vice president of environment, policy and social initiatives, told Reuters. Apple previously signed major suppliers such as Foxconn parent Hon Hai Precision Industry, which assembles many of its products, and Taiwan Semiconductor Manufacturing, which makes Apple's processor chips, to clean energy pledges in 2019. The tech company also announced it was providing funding for 10 smaller renewable energy projects aimed at bringing renewable power to under-resourced communities. The projects include work with communities in South Africa, the Philippines, Colombia and the Oceti Sakowin Power Authority formed by six Sioux tribes in the western US.