Bitcoin mining is supposed to “secure” the blockchain by turning electricity into consensus. But a new study in PNAS Nexus puts a hard number on the part where the system burns power and still produces nothing useful. The researchers estimate that in 2025, around 16,000 megawatts of energy will be wasted by fruitless mining attempts, where competing mining efforts exert massive computational power to obtain the same units of bitcoin.

To help you feel that scale, the study says this wasted energy is roughly equivalent to Switzerland’s entire hydropower generation capacity, specifically the capacity of the country’s 701 hydropower plants, using statistics from the Swiss Federal Office of Energy. It also helps explain why environmental scrutiny has intensified around proof-of-work systems: the wasted energy is not an abstract side effect, it is directly tied to how often the network produces competing blocks that race and then get discarded.

So what’s causing it? The paper points to network latency in bitcoin mining as a driver of “accidental forks.” In the proof-of-work model, miners solve a digital puzzle to earn the right to add a new block of transactions to the chain and receive bitcoin rewards. The first miner to solve the puzzle should win. But in real life, the difference between first and second place can be tiny fractions of a second. When two competing blocks arrive at nearly the same time, the blockchain temporarily contains branches. The block that ends up belonging to the winning longest chain gets validated and rewarded; the competing branch becomes invalid and worth nothing. The energy used to mine the orphaned blocks, plus any subsequent blocks built on top of them before the winner is decided, is energy that ultimately goes to waste.

The researchers frame this as more than inefficiency for inefficiency’s sake. “Despite their indication of a distributed network, accidental forks are an inefficiency of the Bitcoin protocol that leads to wasted computational resources (and thus energy), increasing the cost of network operations and its environmental impact to maintain a given level of security,” they wrote in the study. That is the key executive-level takeaway: if the network’s effective security depends on producing a winning chain, then the rest of the work that produced losers is pure burn. And the study is careful not to assume every miner behaves identically. It builds a theoretical “null model” that explicitly considers elements like network latency and geographic distribution, rather than treating all miners as equal.

The paper also uses the model to quantify other trends in mining operations, especially mining pools. Mining pools are consortiums in which mining operators pool their efforts to maximize their potential success. Here’s where the boardroom risk creeps in. The study identifies a decline in the dominance of Chinese mining pools from 2022 following the country’s ban on bitcoin mining. It also finds high consolidation at the upper level of the mining industry: just three mining pools produce over 50% of new bitcoin blocks. That concentration matters because it risks a “51% attack,” where unscrupulous miners could insert fraudulent information into the blockchain by ensuring they always produce the longest chain and therefore become validated.

Importantly, the researchers add that this level of consolidation distorts the market for processing fees that bitcoin users pay to have their transactions included in the next block. In other words, it doesn’t just raise theoretical concerns about fraud. It can also enable miners to arbitrarily delay the inclusion of specific transactions. For executives tracking crypto infrastructure, this is the uncomfortable combo: proof-of-work not only consumes energy, it also incentivizes coordination and scale, which then creates governance-like leverage for a small number of large players.

Zoom out one more layer. Environmental concerns around bitcoin and other proof-of-work blockchains have been around for years. The source notes a 2023 U.N. report that, in 2021, bitcoin mining’s water usage, primarily for liquid-cooled computer equipment, equated to more than the domestic water use of 300 million people in rural sub-Saharan Africa. And it notes that the wasted-energy figure in this study differs from other estimates of total energy consumed by bitcoin mining activity, which researchers estimate at an annual level of 138 terawatt-hours as of June 2024. That total consumption is higher than the annual energy consumption of several developed countries including Norway and the Netherlands. The new contribution here is that the wasted portion is not merely “part of the ecosystem.” It is tied to protocol mechanics like accidental forks and to real-world network conditions.

Meanwhile, competition is real. The Crypto Carbon Ratings Institute (CCRI) is cited as saying bitcoin is the dominant cryptocurrency by far, with a market capitalisation of more than $1.1 trillion, more than 80% larger than Ethereum. Ethereum, unlike bitcoin, uses a “proof-of-stake” consensus mechanism to establish block authorship and is therefore significantly less computationally intensive. The study notes that while other proof-of-work cryptocurrencies exist, bitcoin’s scale makes it orders of magnitude more power-hungry, and therefore makes inefficiencies like fork-driven wasted energy even more consequential.

For decision-makers, the strategic stakes are straightforward. If you run infrastructure, invest in energy-heavy systems, or advise on risk and regulation, then protocol-level waste and operator-level concentration are not niche details. They can show up as regulatory pressure, reputation and community backlash, and operational cost volatility, all at once. The PNAS Nexus model turns a familiar narrative about bitcoin’s power hunger into a more specific problem: 16,000 megawatts wasted in 2025 by fruitless attempts caused by latency and competition. That number is what makes this story stop being “crypto news” and start being infrastructure math.