Reducing our energy use has the dual benefit of lowering costs and greenhouse gas emissions, and it is a central focus of both our environment, health, safety and social responsibility strategy and our Lean approach to managing the business. We generate and purchase energy primarily for power, processing, heating and cooling. In 2017 energy consumption from Hess-operated assets was approximately 33 million gigajoules (GJ), 13 percent lower than in 2016. Seventy-eight percent of Hess’ energy use was directly generated from our operations, primarily at the Seminole and Tioga gas processing plants and at our production facilities in North Dakota, Denmark, Equatorial Guinea and the Gulf of Mexico. The remaining 22 percent was indirect energy (energy used by utilities to provide net purchased electricity) purchased for the West Texas and North Dakota production operations and the Seminole and Tioga gas processing plants.
In 2017 our U.S. operations accounted for all of our purchased electricity — approximately 790,000 megawatt hours (MWh), or a 12 percent reduction from last year. This reduction is mainly attributable to the sale of our interests in the Permian Basin, including the Seminole Gas Plant. Based on U.S. electricity generation profiles, we estimate that approximately 19 percent of this electricity was generated from renewable sources, primarily wind power. We also support renewable energy through the purchase of renewable energy certificates (RECs) equivalent to at least 10 percent of the net electricity used in our operations. In 2017 we purchased 90,000 Green-e Energy certified RECs for wind power, equivalent to 90,000 MWh or about 11 percent of the electricity purchased for our operated exploration and production assets. In total, including the RECs, approximately 30 percent of our indirect energy use came from renewable sources.