“Only the miners with the cheapest energy can survive, so bitcoin is driven to areas of low or no demand,” says Yan Pritzker, cofounder of the bitcoin trading platform Swan Bitcoin. “Sources of wind and solar are unreliable and therefore have to be overprovisioned. But bitcoin miners are coming in and acting as a buyer of last resort.”

By purchasing energy from renewable sources when it isn’t needed by the grid, the argument goes, bitcoin miners can increase the profitability of solar and wind farms and accelerate the transition to sustainable energy sources. Miners also say consumption figures like those compiled by the University of Cambridge don’t take into account the amount of off-grid energy sources used to power mining, nor the circa 1 percent that run on methane—a byproduct of oil extraction that is otherwise vented or burned away.

A common argument among bitcoiners is that rather than focusing on trying to cut down how much energy is consumed by the network, critics should look at how the network can help expand the amount of renewable energy on the grid. “Bitcoiners understand that the way to reduce emissions is not to use less energy, but to generate orders of magnitude more low-emissions electricity,” says Chris Bendiksen, bitcoin research lead at investment firm CoinShares. “In order to do that, producing low-emission energy must be profitable, something that PoW mining ensures in a wholly unique manner and at scale.”

Although compelling at a surface level, these arguments do not stand up to scrutiny, say bitcoin critics. Pete Howson, an assistant professor on the Environmental Sciences faculty at Northumbria University, likens the common defenses of bitcoin mining to “magic tricks''—sleights of hand that obscure inconvenient truths and “provide the illusion of clean and profitable investment.”

“The only difference between flaring methane and flaring methane for bitcoin,” says Howson, “is that the latter makes fossil-fuel companies more profitable, slowing the transition to green alternatives.” There are even a handful of examples—in New York and Montana—of the additional revenue generated by bitcoin mining giving new life to fossil-fuel plants that had either closed or were scheduled for closure.

Meanwhile, in countries like Iceland, Howson says, bitcoin miners are outcompeting other energy consumers, like recycling plants, which “can’t get access” to otherwise plentiful sources of renewable energy. “There is no such thing as wasting energy sustainably,” he says.

Whether it’s really a waste is at the core of the debate.

The scrutiny of bitcoin’s environmental credentials, says Pritzker, is out of proportion with the emissions it produces, which best estimates place somewhere between 0.1 percent to 0.15 percent of the global total. He asks why bitcoin is singled out, when other industries pollute in larger volumes or are powered by a dirtier mix of energy. The simple answer is that the argument hinges on a matter of personal opinion; it comes down to whether somebody believes that crypto serves a purpose.

If bitcoin is agreed to be of greater societal value than tobacco, say, an industry responsible for a greater volume of emissions, its footprint becomes easier to justify. But if instead, bitcoin is just one big Ponzi scheme, the sums will never line up.