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 2019, energy consumption from Hess operated assets was approximately 28 million gigajoules, 8% lower than in 2018. This reduced energy usage was primarily related to selectively replacing aging gas-fired compressor stations in North Dakota with electric compression. Seventy-seven percent of Hess’ energy use was directly generated from our operations, primarily at the Tioga Gas Plant and at our production facilities in North Dakota, the North Malay Basin, Denmark and the Gulf of Mexico. The remaining 23% was indirect energy (i.e., energy used by utilities to provide net purchased electricity) purchased for our North Dakota production operations and the Tioga Gas Plant.
In 2019, our U.S. operations accounted for all of our purchased electricity – approximately 700,000 megawatt hours (MWh), or a 17% increase from last year, primarily attributable to increased production in North Dakota and the conversion of new compressor stations from gas to electric compression. Based on U.S. electricity generation profiles, we estimate that approximately 25% of this electricity was generated from renewable sources, primarily wind power. We also support renewable energy through the purchase of renewable energy certificates (RECs), so that in total 100% of the net electricity used in our operations is attributable to renewable sources. To offset our purchased electricity that came from nonrenewable sources, we purchased 530,714 Green-e Energy certified RECs for wind power, equivalent to 530,714 MWh or about 75% of the electricity purchased for our operated exploration and production assets in 2019. In total, including the RECs, 100% of our indirect energy use came from renewable sources.