Apple announced today that its business is now powered by 100 percent renewable energy sources. The news is a major victory that the iPhone maker has been working toward for years through the purchase of green energy bonds and other renewable investments in its supply chain and physical infrastructure. The company’s last milestone, announced two years ago, was 93 percent of its worldwide operations running on clean energy.

The announcement comes just one week after Google announced that it now purchases enough renewable energy to offset its global energy consumption. Similarly, Apple’s global operations, including some suppliers in China and facilities in places without access to clean energy, are not technically 100 percent renewable, meaning not every single joule or electron used is initially created by wind, solar, or other green energy plants and farms.

Apple is not technically powered by 100 percent renewable energy

For instance, Apple Stores that are powered by municipal power grids cannot reliably use clean energy because once electricity enters the grid, you can no longer determine its source or cleanliness. As a way to account for that, Apple purchases what are known as Renewable Energy Certificates, or RECs, which are a tradable commodity that guarantee the cleanliness of an energy source. (Think of it like the opposite of a carbon tax.) Apple also invests in wind, solar, and other clean energy facilities around the globe, builds its own energy sources, and ensures that any new offices and plants it constructs do actually run on 100 percent clean energy, like the newly opened Apple Park campus. The company says it also puts excess green energy into the grid, so it can be used by others.

Apple says its approach differs from others in the tech industry in some key ways. For one, the company says it always seeks to fund and build its own energy projects, and does so for around two thirds of all of its energy needs globally. “Where it’s not feasible to build our own generation, we sign long-term renewable energy purchase contracts, supporting new, local projects that meet our robust renewable energy sourcing principles,” reads the company’s 58-page Environmental Responsibility Report published last year. “In cases where we aren’t able to create new renewable energy projects ourselves due to local constraints, we directly purchase renewable energy from newer projects in nearby markets, or through available utility green energy programs. Apple says that when it purchases REQs, “we require that they are Green-e Energy certified and come from the same power grid—and preferably the same state — as the Apple facility they support.”

Apple is working toward making sure that every single retail store, office, data center, and manufacturing facility worldwide, in all 43 countries it operates in, run on 100 percent clean energy. That’s not possible today, given the dependency on electric grids, regional utility monopolies, and energy hurdles in manufacturing hubs like China, among other factors. But Apple is pledging to get there as fast as it can.

“We’re committed to leaving the world better than we found it. After years of hard work we’re proud to have reached this significant milestone,” Apple CEO Tim Cook said in a statement. “We’re going to keep pushing the boundaries of what is possible with the materials in our products, the way we recycle them, our facilities and our work with suppliers to establish new creative and forward-looking sources of renewable energy because we know the future depends on it.”

“We’re committed to leaving the world better than we found it.”

Apple’s press release breaks down some of the numbers and further explains Apple’s timeline to its commitment to combat climate change, something Cook has spoken publicly about before. The chief executive notably clashed with Trump over the US exiting the Paris climate accord last year. Cook also told investors in 2014 that they should dump their Apple stock if they didn’t take seriously the company’s commitment to green energy and sustainability and questioned how much Apple spends on those projects. Just last week, Apple pushed back against the Environmental Protection Agency’s proposal to repeal the Clean Power Plan.

“Apple currently has 25 operational renewable energy projects around the world, totaling 626 megawatts of generation capacity, with 286 megawatts of solar PV generation coming online in 2017, its most ever in one year,” reads Apple’s press release from today. “It also has 15 more projects in construction. Once built, over 1.4 gigawatts of clean renewable energy generation will be spread across 11 countries.”

Since 2014, Apple says all of its data centers have been powered by 100 percent renewable energy. “And since 2011, all of Apple’s renewable energy projects have reduced greenhouse gas emissions (CO2e) by 54 percent from its facilities worldwide and prevented nearly 2.1 million metric tons of CO2e from entering the atmosphere,” the release reads.

Update April 9th, 4:17PM ET: Clarified that Apple, like Google, is not actually 100 percent powered by clean energy, but it uses the term to signal that it buys enough green energy to offset its global power consumption.

Update April 9th, 5:05PM ET: Added additional details about Apple’s renewable energy efforts.