Over the past year, Meta has funded the construction of at least a dozen natural gas power plants, including a project that alone will burn enough natural gas to generate as much electricity as the entire state of South Dakota uses.

Meta is now no longer part of RE100, a corporate renewable energy initiative, after a decade of membership, the company confirmed to TechCrunch today. The breakup was mutual, according to a Meta spokesperson.

The exit caps months in which Meta expanded its commitment to fossil fuels to power its artificial intelligence data centers and raises the obvious question: What does “clean energy” really mean for a company that continues to build gas plants while calling itself renewable?

RE100 is a project of the Climate Group, a UK-based non-profit organization co-founded by former Prime Minister Tony Blair. The initiative provides political and technical support to corporations seeking to transition to 100% renewable energy. Meta-competitors Apple, Google and Microsoft remain among the group’s 444 members. Recharge News was the first to report Meta’s departure.

While Meta declined to comment on the reasons behind the departure (and the Climate Group did not respond to TechCrunch’s inquiry), the nonprofit recently updated its guidance for companies, mandating more rigorous reporting on progress toward renewable energy goals. Previously, Meta told RE100 that it would “run all of its operations on renewable electricity by 2020.”

Like many technology companies, Meta’s adoption of AI has led it to secure large amounts of power for its data centers, and while the company continues to purchase renewable energy, it has embraced natural gas like few others.

Meta’s toe in the water was a 200-megawatt behind-the-meter gas power plant in Ohio, announced in June last year, that will power one of its data centers.

Two months later, Meta said it would build three large natural gas power plants in Louisiana to supply electricity to its Hyperion data center. Then in April, the company announced it would finance seven more natural gas power plants for the same project. Combined, the 10 power plants will generate 7.5 gigawatts, enough electricity to power South Dakota and then some.

Meta, through a spokesperson, told TechCrunch that it remained committed to matching its data center’s electricity use “with 100% clean, renewable energy.”

There is a lot to promise. While natural gas burns cleaner than coal, it still produces significant amounts of pollution. A single 1-gigawatt data center operating 24/7, fueled exclusively by natural gas, will release 438 metric tons of nitrogen oxides, 149 metric tons of fine particulate matter, 61 metric tons of sulfur oxides, and 298 metric tons of carbon monoxide. These pollutants contribute to a variety of diseases, including asthma, cancer, cardiovascular disease, and dementia, among many others.

Meta can still claim to be 100% renewable by purchasing environmental attribute certificates. This allows companies to invest in a solar farm in Arizona, for example, while building a data center in Ohio. As long as the solar park generates enough energy in a year to offset data center usage, Meta considers it 100% renewable.

Most companies have addressed their renewable energy goals using annual matching, but some, including Microsoft, strive to match their electricity consumption hourly. This stricter approach would align energy production with how data centers use electricity. It also encourages companies to invest in projects that combine renewable energy with batteries, as Google did earlier this year in Minnesota, rather than polluting projects like Meta’s Hyperion power plants.

Meta is not the only one betting on natural gas (both Google and Microsoft have recently invested in large fossil fuel projects), but it has made the biggest bet. The withdrawal or elimination of a voluntary industry group is not always big news, but the timing, in the midst of Meta’s fossil fuel development, makes the change hard to ignore.