If you're going to question the validity of an assertion please provide more than just a counterassertion.
Then any "published study" on this topic is automatically going to be flawed as well?
Their research indicates that a minority of mining is done using renewable resources:
> The survey findings estimate that on average 39% of proof-of-work mining is powered by renewable energy, primarily hydroelectric energy.
It also specifically addresses this popular claim of mining being powered mostly by renewables:
> China’s oversupply of hydroelectric energy during the rainy season has often been used as evidence in claims that a vast majority of mining is powered by environment-friendly power sources. While it is true that the Chinese government’s strategy to ensure energy self-sufficiency has led to the development of massive hydropower capacity, the same strategy has driven public investments in the construction of large-scale coal mines. Like hydroelectric power plants, these coal power plants often generate surpluses. It should not come as a surprise then that a significant share of hashers in the region equally report using both hydropower and coal energy to power their operations.
A cursory Google search says the percentage of renewable energy in the US and China is ~11% and ~23% respectively. The disparity between that and an average of 39% for crypto mining specifically does not seem to be factored in.
> The great unanswered question faced when exploring cryptodamages is that while we can identify select geographic hotspots of production we currently do not know in the aggregate where the electricity used in cryptocurrency mining is physically produced. This is because we, like Krause and Tolaymat, do not know the physical locations of cryptocurrency miners, whether individuals, groups or aggregates in, say, a region or country. There is considerable evidence of concentration of mining operations in particular locations, typically where reliable electricity is cheaply available, though, precise data are lacking. In the US, perhaps the most well-known concentration is the Mid-Columbia Basin area in central and eastern Washington State, where cheap electricity is produced by hydropower along the Columbia River, however, mining in other US locations also occurs. There is also evidence of large mining camps in China. With time and emergent research there may be improved information about the amounts of electricity devoted to mining cryptocurrencies for particular locations or regions, but it is currently not available.
It would be interesting to see the results of their analysis if recalculated using the more granular CCAF survey data.
Otherwise nonsense claims can easily destroy the discussion by DoSing the opposition.