Did Bitcoin Mining REALLY Turn a Glacial Lake Into a Giant ‘Hot Tub’?

You may have heard this week that a fossil fuel power plant that mines Bitcoin has turned Seneca Lake, the largest of the glacial Finger Lakes in New York State, into a giant hot tub. That would be truly devastating environmental news if it were true, but is it really possible?

The claim originated in a recent NBC piece that quoted Seneca Lake homeowner Abi Buddington as saying that "the lake is so warm you feel like you're in a hot tub." Buddington owns a home near the Greenidge power station, which since last year has used some of its energy to mine Bitcoin. The integration of Bitcoin mining has kept the plant running—Greenidge was mothballed in 2011 after 74 years in service as a coal-fired plant but private equity firms stepped in and converted it to a natural gas plant in 2017 and added Bitcoin miners to the operation last year. 

This is an anecdote in an interesting article about how big firms are turning fossil fuel power plants into Bitcoin mining operations; it’s also been glommed onto by both Bitcoin boosters and environmentalists as a flashpoint in the broader, crucial debate about Bitcoin’s environmental impact. Several articles highlighted Buddington’s “hot tub” quote and took it even further. One headline said Bitcoin mining made the lake into a “giant hot tub,” and another (since updated) headline said Greenidge is “turning a 12,000-year-old glacial lake into a hot tub.” The headlines angered Bitcoin proponents, who are busy minimizing the environmental impact of the electricity-powered cryptocurrency, which has recently become a point of heated contention among environmental advocates and those who simply think Bitcoin is a bad use of resources. 

“A ludicrous claim,” said Zack Voell, a researcher at Bitcoin mining marketplace Compass Mining. Voell, along with other Bitcoin advocates, argues that “the math doesn't even start to add up,” and that it’d take more than Greenidge’s few thousand Bitcoin miners to turn a glacial lake that’s replenished with 328,000 gallons of underground spring water every minute into a Jacuzzi.

Buddington clarified to Motherboard that she meant that the water near the power plant’s discharge pipes is like a hot tub—she discovered as much while kayaking up the Keuka Outlet, which empties into Seneca Lake—but the rest of the lake seems to be unaffected, she said. A spokesperson for NBC said that Buddington’s quote was “accurately presented in the piece.”

Gregory Boyer, the acting director for the Great Lakes Research Consortium, told Motherboard that even the claim that the local area is like a hot tub is “overblown.” 

Boyer’s research on superheated water from power plants shows that water cools within a few hundred yards. Power plants such as Greenidge take water from the lake with intake pipes and use it to generate power, and then expel the hot water back into the lake. While Greenidge’s refuse pipe pumps out water at 108 degrees, Hobart and William Smith College records the average temperature of the whole lake over the past month at 67.3 degrees. This is not out of line with summer recordings at the lake taken over the last several years, according to readings taken by the USGS, though it’s important to note that researchers have found that the lake has, generally speaking, been getting warmer over the years. Hobart and William Smith College has recorded a steady ~0.2°C increase to the overall surface of the lake since the mid-90s. John Halfman, a professor of hydrogeochemistry at Hobart and Smith, attributes this to global warming, rather than Greenidge specifically.

So, if Jacuzzis are about 104 degrees, it might be fair to say that the water directly next to the outlet pipe is like a hot tub—the rest is not. “Sure, you can feel the difference in the temperature,” says Boyer, but “you're not going to feel it go up to 100.”

A 66 square mile hot tub would be unimaginable, after all. Halfman told Motherboard it’s like dropping “a thimble of very hot water in a cold bath.” 

Seneca Lake is thus not a giant hot tub, but that doesn’t mean Greenidge is off the hook, environmentally speaking. Research over the years has homed in on the deleterious effects of power plants on waterways and the wildlife within. Environmental advocates note that intake pipes can be harmful to fish, for example, while Boyer said that year-round hot water sets up the conditions for harmful algal blooms nearby. While they are normally killed off in the winter, Boyer said, these blooms poison the water, which could prove fatal to residents that drink it—or, more likely, wildlife, pets, or campers.

Although Halfman observed the smallest number of harmful algal blooms in Seneca Lake on record last year, he says that the plant hasn’t been online long enough to cause a difference and has not finished expanding. Boyer says that heating up the area around the discharge pipe would in time “spread [harmful algae] around the rest of the lake.” 

“It is an indirect effect, but an effect nonetheless,” he says. He also predicts that the hot water “will change fish spawning in the region of the power plant (localized effect) but that will probably not show up as a lake wide effect.”

A spokesperson for Greenidge said that “there is no evidence that indicates that Greenidge’s operations are contributing to Harmful Algal Blooms,” and that Greenidge is investing several million dollars to prevent poisonous algal blooms from forming. According to the spokesperson, “there is zero negative impact on massive Seneca Lake from Greenidge’s fully-permitted power generation and bitcoin mining operation in New York State.”

So, the truth is that Seneca Lake is not a gigantic, roiling hot tub because of Bitcoin mining. However, there are well-founded concerns about the effects of power generation along the lake, and about the use of fossil fuels to mint new bitcoins. As society moves towards electrifying more things, from money to cars, we’re going to have to get comfortable with these sorts of discussions becoming more frequent.