In mainstream media, bitcoin is a villain of sorts. It seeks to dismantle the existing economic system and uses far too much energy. But those characterizations may not be entirely true. A new report released by Cambridge University posits that bitcoin may not be as environmentally harmful as previously imagined.

The cryptocurrency benchmarking study states that renewable energy is increasingly becoming a part of the energy mix used at bitcoin mining facilities. The study estimates that roughly 28% of the total energy supply for both small and large facilities is generated from renewable energy sources. “Less than a quarter of identified miners do not use any form of renewable energy sources,” the study states.

The total amount of energy consumed by the top six currencies that use Proof of Work - the mining algorithm used to generate the currency - is between 52 and 111 TWh of electricity per year. The midpoint of this estimate (82 TWh) is equal to the total energy consumed by Belgium. (Earlier estimates had pegged bitcoin’s energy use as being equal to that of Ireland). It is also equal to 0.01% of the world’s global energy production, the study’s authors write.

There are nuances in these estimates. For example, based on the algorithms they use, different cryptocurrencies require different amounts of energy. Bitcoin, the original cryptocurrency, uses a Proof of Work algorithm in which miners compete to solve cryptographic puzzles. The difficulty of these puzzles is one of the factors that determines its availability and is adjusted every 2016 blocks or two weeks, approximately. The greater the difficulty, the more the computation power required to mine a bitcoin and, consequently, the more its energy use. But Ethereum, which was the world’s second most valuable cryptocurrency until recently, is transitioning to a Proof of Stake algorithm, which does not require mining. Technological refinements to ASIC miners, which are used for PoW mining, may also have the potential to decrease energy usage for mining.

Energy requirements are a significant factor for large miners to determine the location of their next cryptocurrency mining facility. The reason is obvious. Electricity use affects their economies of scale. Only 23% of small miners base their mining decisions on electricity use. In some cases, large miners have struck deals with local electric authorities for favorable rates. This is especially the case in China’s Sichuan province, where hydroelectric facilities are being used to generate power. But the trend does not seem to have caught on in North America, where small miners have to shell out extra for electricity use.

This is not the first study to comment on renewable energy use for mining cryptocurrencies. Coinshares, a UK-based research firm, came out with a study last month that estimated renewable energy accounted for 77.6 percent of overall energy use in bitcoin mining. But it did not provide concrete proof for its estimates.