An American bitcoin mining company claims creating the world’s largest cryptocurrency produces no greenhouse gases. This is false; the process requires a significant amount of energy, experts say — which can come from carbon-emitting sources such as natural gas or coal-fired power plants.
“Bitcoin mining has zero carbon emissions,” says an April 10, 2023 tweet from Riot Platforms Inc.
The post includes a video of a man testing for emissions outside a bitcoin mining facility in Rockdale, Texas.
Riot published the clip in response to an April 9 New York Times article about the environmental cost of bitcoin mining in the US. The video accumulated more than 1.3 million views.
“We’re here out in Rockdale, Texas,” Pierre Rochard, vice president of research at Riot, says in the footage, displaying a device measuring carbon dioxide. “We’re going to go inside the mining facility and we’re going to see how much is this number going to go up. If the number does not go up, then the mining rigs are not emitting any CO2.”
After checking readings outside and inside the facility, Rochard claims this data proves that bitcoin mining “does not emit any CO2.”
“I think the science is conclusive,” he says.
The company also issued a press release (archived here) with a more detailed explanation.
“To be clear, our Bitcoin mining operations do not generate any greenhouse gas emissions, similar to any other data center for Facebook, Amazon or Google — yet we have been singled out,” the statement says. “Our data center uses electricity from the Texas grid, which is the cleanest and most renewable energy-sourced grid in the United States.”
But bitcoin mining does have a carbon footprint, experts told AFP. Centers creating the cryptocurrency require massive amounts of energy, not all of which is sustainable.
What is bitcoin mining?
The only way to make bitcoin is by using a network of powerful computers to solve complex mathematical questions.
The first computer that solves the problem unlocks the next block of bitcoins that are released into circulation. Then the cycle starts over again as computers attempt to find the next block.
Margot Paez, a climate adaptation fellow at the Bitcoin Policy Institute, compared the bitcoin mining process to a “game” or “a puzzle.”
“Each computer is like a lottery ticket,” she said. “That means if there are 100 computers on the network trying to win the game of getting the reward — the bitcoin is the reward — my one computer has, all things being equal, a 1/100 chance of winning.”
Bitcoin mining facilities have multiplied in the US since China halted the activity in 2021 — and they consume a lot of energy.
The Cambridge Centre for Alternative Finance estimates that the bitcoin network has an annual electricity consumption of 145 Terawatt hours (TWh).
“To put this into perspective, this level of energy consumption would place bitcoin among the top 30 energy-consuming nations globally,” said Fengqi You, an energy systems engineering professor at Cornell University.
The White House issued a press release in September 2022 warning about the increased demand for cryptocurrency and its implications for US climate goals.
“The United States is estimated to host about a third of global crypto-asset operations, which currently consume about 0.9 percent to 1.7 percent of total US electricity usage,” the statement says. “This range of electricity usage is similar to all home computers or residential lighting in the United States.”
The White House said that “depending on the energy intensity of the technology and the sources of electricity used, the rapid growth of crypto-assets could potentially hinder broader efforts to achieve US climate commitments to reach net-zero carbon pollution.”
Lena Klaassen, a doctoral researcher at ETH Zurich’s Climate Finance and Policy Group, said Riot’s claim “is not correct as bitcoin miners are also relying on power sources from fossil fuels.”
If the computers are powered by solar or wind, then the facility would “be considered carbon-free,” said You of Cornell. However, if a power plant burning fossil fuels is generating the energy, then he said “we can’t consider bitcoin mining free from any carbon emissions.”
The Crypto Carbon Ratings Institute ranks Riot’s operation as the fifth most carbon-intensive of all leading bitcoin mining companies. Riot also claims its Rockdale center is the “largest bitcoin mining facility” in the US.
The New York Times and WattTime, an environmental technology nonprofit, estimated the facility contributes 1.9 million tons of carbon emissions per year.
Riot’s mining site gets its energy from Texas’s ERCOT grid, whose power sources in 2021 comprised 61 percent fossil fuels and 28 percent wind and solar, according to the state comptroller’s office.
While Texas is a leader in renewable energy production, the state still relies on fossil fuels and says they will remain “a crucial part of the energy mix for the foreseeable future.”
A greener bitcoin mining process may become possible as the power grid gets more sustainable, according to Klaassen of ETH Zurich. But she warned that “until then, consuming large amounts of electricity in a grid that does not fully run on renewable energy sources will be associated with causing emissions.”
AFP has fact-checked other claims about carbon emissions here, here and here.