Fact check: Is Bitcoin catastrophic, insignificant or a strong net positive for the environment?
31 min read
Table of contents
- Environmental Bitcoin Myths
- Bitcoin's environmental impact: state of the evidence
- Is Bitcoin an environmental catastrophe?
- Is Bitcoin worth the environmental impact?
In their extreme positions, all three of these assessments are misleading, and all three contain some nuggets of truth. Bitcoin is the most visible example of hyberbolic claims both for and against, especially in the environmental arena.
So what is the significance of Bitcoin's emissions? Is it catastrophic? Negligible? A powerful green tool in tackling climate change?
Environmental Bitcoin Myths
Before considering the merits of each claim, I want to look at examples of where these claims have gone beyond the evidence to become myths, as a way of highlighting the importance of questioning our own starting points, whatever they may be and seek evidence-based answers even if they turn out to be less conclusive or categorical than we might like.
Myth 1: Bitcoin as environmental catastrophe
One particularly impactful (and alarming) 2018 article in Nature was titled Bitcoin emissions alone could push global warming above 2°C, affirming a timeline of under 20 years, and 11 years in the worst-case scenario. Within months of its appearance, multiple peer-reviewed responses exposed fundamental flaws in the article's assumptions, and a recent methodological review of the field repeatedly used that article as an object lesson in quality gaps.
Nevertheless, that claim continues, as of 2023, to be cited by highly prominent voices like Greenpeace and Ben&Jerry's and even in recent academic literature.
Myth 2: Bitcoin as "Meh"
Bitcoin's own official environmental rationale is really an exercise in whataboutism, which argues there are many worse polluters, that metrics are hard, and that Bitcoin can be and sometimes is powered by renewable energy.
All this may be true, but it does not mean Bitcoin itself is not actually address the issue of whether Bitcoin is or is not in fact a significant source of pollution accelerating global warming.
Finally, Bitcoin argues that its ethical benefits outweigh its environmental costs, although it does not dedicate much effort to proving its case, and one senses it is more of a fig leaf than an earnest case being made. The rhetorical energy of their article is that the environmental concerns are ultimately negligible.
Myth 3: Bitcoin, green panacea
More emphatic than Bitcoin's own argument, even if building on arguments seeded in its article, is the unabashed environmental optimism of a widely syndicated post by Bitcoin lobbyist Dennis Porter, boldly titled: Bitcoin Mining Is Good for the Energy Grid and Good for the Environment.
The argument goes like this:
There is a huge amount of unused (stranded) renewable energy being thrown away (curtailed) and going to waste.
Sunshine and clouds are unpredictable, so solar energy might become suddenly available at times of very low domestic use, creating surpluses that cannot be stored, and therefore become stranded, and wasted.
Because Bitcoin mining hardware can power down when energy is being consumed by the electricity grid, and power up when it is about to be curtailed, Bitcoin mining could run entirely on currently wasted renewable energy, switching off at peak times, meaning it wouldn't contribute new emissions.
Bitcoin renewable electricity demand would generate financial incentives to accelerate investment in green electricity infrastructure, improving the electricity grid and accelerating the green energy transition.
Additionally, methane (an acutely terrible greenhouse gas), is also regularly flared from landfills, abandoned wells, and oil and gas operations. Potter points out that such surplus methane could instead be turned into electricity to be consumed by co-located miners, turning Bitcoin into a carbon capture tool preventing the methane from getting trapped in the atmosphere.
On the face of it, Porter's article offers an excellent application of carbon-aware computing, and specifically time, demand and location shifting patterns. Such approaches are very much the cutting edge of current efforts to green the environmental impact of computing, and the Adora Foundation's Incubation Lab is supporting a range of fantastic carbon aware projects in this area, from machine learning to cloud computing, and from APIs to UI component libraries.
There are however a few caveats to this carbon-aware, energy-responsive, carbon-capturing Bitcoin utopia. The premise that Bitcoin could be good for the energy grid and good for the environment, even if accepted, does not support the title of the article, which claims that Bitcoin already is good for the energy grid and the environment.
Porter refers to an example of voluntary Bitcoin mining suspension at peak grid usage times in exchange for energy credits miners can redeem at non-peak times. This is part of a large scale experiment in using Bitcoin as a tool for grid stabilisation in the face of unpredictable renewable energy availability.
To ensure safe operation, voltage, frequency, and other electrical aspects of the grid must be kept within specified ranges. This requires a constant balance of electricity supply and demand. If the balance is lost, blackouts, brownouts, and other grid disruptions can ensue. An increasing share of wind and solar in the energy mix introduces unpredictable peaks and drops, so whereas in legacy energy systems the grid could be stabilised on the supply side in a planned way; the more renewable energy is part of the mix, the more you need demand to adapt to an ever changing supply to keep overall usage within the necessary ranges.
Porter's example is one such demand response solution, with Bitcoin being used to stabilise the grid. There are two types of such schemes:
Price-responsive Bitcoin mining, where miners are located behind-the-meter (BTM) directly at renewable power plants, mining when the market price for renewable electricity is low and refraining from mining when it is high.
Bitcoin miners acting as "load resources" in conventional demand response programs, enabling them to participate in day-ahead markets. This helps with electricity demand, but does not guarantee that the energy mix powering Bitcoin mining is renewable. Porter does not mention this dimension, which has the larger share in the Texas experiment.
Let us take a scenario where all miners operate in a price-responsive, renewable energy scheme. Even in this scenario, the Texas Bitcoin miners reduce peak time mining, but maximise non-peak time mining, adding to net energy demand overall, placing the entire grid under strain, raising electricity costs. These and other issues have led to an ongoing Cogressional investigation.
Which is to say, above and beyond the energy mix powering the grid, is the constantly growing energy demand. From this perspective, even if one were to grant Porter's most idyllic scenario, where Bitcoin is mined in an energy-aware manner, running mostly on otherwise wasted renewable energy, as long as net energy demand continues to grow, we face a host of negative consequences.
The strains and risks above have resulted in a permitting slowdown in the experiment that has choked the rate of Bitcoin expansion, while generating demand for new infrastructure investment, although not exlusively or primarily for green energy infrastructure.
The same kind of issues arise when considering Bitcoin as a methane emissions reduction mechanism.
Potter's methane combustion use case, building on research by ESG-oriented Bitcoin promoter Daniel Batten, also looks on the face of it like a promising carbon capture solution but it's very far from guaranteed. The White House's moderate stance on the subject rings true:
Crypto-asset mining that installs equipment to use vented methane to generate electricity for operations is more likely to help rather than hinder U.S. climate objectives. However, unless the CO2 is captured and stored, using vented methane at oil and gas wells will still generate CO2 emissions and contribute to climate change. Using vented or flared methane for crypto-asset mining must also be assessed against other uses for this methane, such as hydrogen production or transporting the methane via pipeline to end-users.
Climate and Energy Implications of Crypto-Assets in the United States
Environmentally minded Bitcoin miners could indeed adopt and adapt this approach with potentially beneficial impacts. Meanwhile, environmentally indifferent Bitcoin entrepreneurs don't have any intrinsic incentives to distinguish between green and non-green energy. Bitcoin mining could create perverse incentives that end up stimulating methane and flaring demand, such as intentionally flaring methane to earn rewards.
More generally, there is no Bitcoin-native reason for miners to limit themselves to stranded green energy, or in the case of methane and similar fossil fuel cases, to be sensitive to any environmental constraints. This has even meant that, in pursuit of cheap electricity, miners have gone as far as resurrecting previously shuttered fossil fuel plants for cheap electricity.
The gap between the green Bitcoin dream and its implementation at scale is not insignificant, and the challenges are not mentioned once in Porter's pitch.
Bitcoin's environmental impact: state of the evidence
Life Cycle Analysis (LCA) is the most commonly recommended approach for calculating environmental impacts and comprehensively estimating scopes 1-3 emissions.
This is particularly hard to do when it comes to Bitcoin because of the lack of observability of its highly decentralised network of mining equipment. There is accordingly vanishingly little research outside direct energy consumption studies of Bitcoin.
A Single Life Cycle Analysis of Bitcoin
There are no studies at all estimating Bitcoin's scopes 1-3 emissions, and only a single 2019 reference study by Kohler and Pizzol attempting a rather speculative Life Cycle Analysis of Bitcoin as a whole. The authors acknowledge the paucity of data and high levels of uncertainty and attempt to mitigate it via stochastic simulation and sensitivity analysis for all parameters.
This sole study estimates that the hardware production and end of life (EOL) stages of Bitcoin mining devices account for 0.932% and 0.025% of Bitcoin's emissions, respectively, with the preponderance of CO2 emissions pertaining to Bitcoin's use phase, that is, its mining activity.
Corroborating evidence for Kohler and Pizzol's model comes from a bottom-up Life Cycle Analysis of a single behind-the-metre Bitcoin mining operation at a gas-powered electricity plant in the USA. That study supported the 0.9% finding above for Bitcoin mining equipment production, plus 21% for the gas-based electricity production life cycle, and the remaining emissions pertaining to the use phase. This study did not look at end of life equipment stage, accepting Kohler and Pizzol's 0.025% figure and considering it negligible.
That tiny 0.025% of total emissions, even if considered accurate, should not be regarded as negligible. It obscures the magnitude and consequences of an estimated 30.7 metric kilotons of Bitcoin-related e-waste generated annually (as of 2021), potentially doubling at peak Bitcoin prices.
Blitcoin's electricity consumption: best estimate
The LCA studies above, preliminary though they are, suggest that the much more widespread direct energy and emissions estimates for Bitcoin may well furnish a credible ballpark, with a c. 1% addition from missing hardware manufacture and disposal attributions.
Of these direct energy estimates, the most credible "best guess" (and it is just that) is generally accepted to be the Cambridge Bitcoin Electricity Consumption Index (CBECI). CBECI over-estimates the prevalence of older, more polluting mining equipment, leading to likely over-estimates of electricity consumption. On the other hand, CBECI likely significantly over-estimates Power Usage Effectiveness (PUE) implausibly putting it on a par with best-in-class Google Data Centers and giving no evidence for its calculation. This would mean undercounting the power consumption.
Furthermore, CBECI estimates include life cycle emission factors for the various electricity generation technologies, but not for the manufacture and disposal of Bitcoin mining equipment, and therefore cannot be considered a Life Cycle Analysis (LCA) in their own right, as the authors themselves acknowledge.
One caveat in looking at the CBECI figures is that they represent credible ballparks for Bitcoin's current energy and carbon intensity, but caution should be exercised when projecting past rates into the future. Follow-up research by the authors of the 2019 LCA study modelled several future scenarios, showing Bitcoin's environmental impact could dramatically increase and dramatically reduce based on just 3 variables (with many more mentioned but unaccounted for), using the same Life Cycle Analysis model as the original 2019 study.
Having said that, these are the figures for Bitcoin's direct energy consumption:
The CBECI estimates Bitcoin's annualised electricty consumption at 120 TWh.
It also estimates Bitcoin's annualised greenhouse gas emissions at 60 metric tons of CO2.
Together with Kohler and Pizzol's 2019 LCA study, the CBECI could be used to make a start on scopes 1-3 estimates for Bitcoin, although this has yet to be undertaken. This would be a valuable area for future research.
Quantifying Bitcoin's electricity hunger: Proof-of-Work consensus as perverse incentive
Beyond any direct electricity consumption measure at any given time, assessing the significance of Bitcoin's environmental impact is linked to whether that consumption is likely to grow, remain constant, or diminish over time. From this perspective, the real environmental threat from Bitcoin is arguably not its energy consumption at any given time, but its constantly growing energy demand.
In Proof-of-Work consensus algorithms, energy voraciousness is a feature, not a bug. As one industry participant expressed it at Intel's recent Web3 and Sustainability consultation with various blockchain companies:
“We’re very concerned about digital assets like Bitcoin that are wasteful by design. The incentives baked into the code call for using more and more electricity, the more popular they become, not less and less.”
Indeed, there are fundamental financial and security incentives baked into Proof of Work systems that make energy consumption an indicator of the blockchain's overall profitability and safety.
As a bitcoin miner, the more mining equipment you deploy, the more energy you consume, and the greater your financial profits. There are moderating factors, but the principle holds.
As an investor, the more computation is taking place in the network, the more energy is consumed, and the more secure your assets are.
Energy consumption is thus a simplified but powerful proxy for Bitcoin's overall profitability and security. Which explains why constant improvements to Bitcoin's energy efficiency have failed to diminish net electricity consumption and emissions. On the contrary, as mining hardware has become more and more energy efficient, energy consumption has grown in a pretty reciprocal curve.
This is to be expected. In a system as heavily incentivised as Bitcoin, efficiency gains make possible more mining and more computation for the same electricity. Instead of electricity diminishing to stay within previous usage electricity demand grows to achieve more consumption for the same price, leading to increased total emissions, a rebound effect known as Jevon's Paradox.
How significant is Bitcoin's environmental impact?
The facts are clear. At approximately 120 TWh and 60 MtCO2e, per year Bitcoin is environmentally costly. More so than its most ardent evangelists would claim, less so than its most ardent detractors would warn.
The following comparison by the CBECI authors is illustrative:
The Bitcoin's electricity consumption worldwide is roughly equivalent to that of all fridges in the USA, with a lower carbon footprint, given the embodied carbon of fridges is much higher than that of Bitcoin miners. Taking the mining analogy literally, the authors further make the point that global Bitcoin mining is roughly equivalent to the 130TWh consumed by global gold mining.
I think the closest like for like comparison might be data center usage, as both are computing-focused operations, and both show similar incentives. Sticking to the CBECI comparison for consistency, Bitcoin's total electricity use is equivalent to c. 60% of the global electricity consumption of data centres.
On the one hand, data centres power hundreds of times more applications and utilities than Bitcoin's much narrower uses, so one could argue that the amount of electricity consumption used for the amount of utility gained, shows Bitcoin in a very unfavourable light.
On the other hand, and for the exact same reason, data centers' scope 3 emissions are dramatically greater, since so many energy consuming tools would be inconceivable without them. The state of the art research by Freitag et al, notes an approximate research consensus on emissions from data centers at approximately 130 MtCO2e. They do go on to suggest this is an under-estimate truncating elements of the supply chain, but that's a topic for another post.
If we take CBCI's much less rigorous emissions estimates as broadly credible, that would mean that while data centers consume 40% more electricity than Bitcoin, they generate 200% more CO2 emissions than Bitcoin. We are not in fact comparing like with like, given that CBCI's estimates are not life cycle analyses, but given we have already established a likely addition of 1% from life cycle assessments, the numbers do remain broadly comparable pending more rigorous LCA research into Bitcoin. From this perspective Bitcoin, while arguably less useful, is also less polluting than data centers in the round.
Less commonly discussed are environmental impacts beyond CO2. As the most recent White House report on the climate implications of crypto-assets in the United States summarises:
Besides purchased grid electricity, crypto-asset mining operations can also cause local noise and water impacts, electronic waste, air and other pollution from any direct usage of fossil-fired electricity, and additional air, water, and waste impacts associated with all grid electricity usage. These local impacts can exacerbate environmental justice issues for neighboring communities, which are often already burdened with other pollutants, heat, traffic, or noise.
Climate and Energy Implications of Crypto-Assets in the United States
Is Bitcoin an environmental catastrophe?
Judging the significance of Bitcoin's emissions
Currently, no, it is not. Turning this time to CBECI's comparison of CO2 emissions:
60 million tonnes of CO2 is not nothing. It is equivalent to putting 13 million petrol cars on the road for a year, or (fun fact) every car in Nigeria. More painfully, using the Mortality Cost of Carbon measure, it would be accountable, in 2022 alone, for some 13,500 deaths from its causal share of extreme heat events due to global warming, by 2100. We cannot therefore dismiss Bitcoin's environmental impacts as negligible. They are in fact grave.
But in the context of other technology uses, it is nowhere near comparable to the alarm caused by many more damaging digital industries and tools. As highlighted in the comparison above, US video games, in the sole study devoted to the subject, have been estimated to be responsible for 24 million tonnes of CO2 emissions. The US accounts for less than 20% of the global gaming industry. We have no actual research on the global carbon footprint of gaming, but taking US numbers as indicative of the whole, we can roughly say that video games globally emit nearly double the CO2 emissions of Bitcoin, while evoking less than 1% of the environmental panic.
If the question however is framed in terms of its potential and likelihood of becoming environmentally catastrophic in the near term, the answer becomes more complicated. Bitcoin's electricity consumption has grown by 137% in the last 5 years, or an average of 27% per year. In a linear trajectory, that would mean Bitcoin's electricity consumption and associated emissions would double roughly every 4 years, a dangerously compounding effect in the face of accelerating global warming.
But as emphasised earlier, Bitcoin's electricity consumption cannot be approached in linear terms. In the wake of the well-documented crypto crisis, Bitcoin's electricity consumption rose by 3% in 2022, whereas in 2021 it rose by 53%. The 27% average is clearly unreliable, if not meaningless.
Pizol et al modelled 4 scenarios for Bitcoin's future Global Warming Impact:
a linear (business as usual) scenario.
a location-sensitive scenario where new mining facilities are only installed in more competitive places with lower energy prices. The Global Warming Impact rose by 31%
an equipment-sensitive scenario, where only more efficient mining equipment was used in new bitcoin mining projects. The Global Warming Impact decreased by 48%
a scenario where new bitcoin projects grew only in cheaper locations while using only the latest, more efficient mining equipment. The Global Warming Impact decreased by 32%
This was used to illustrate how misleading it can be to create linear prediction models, where Bitcoin network growth equates to emissions growth in a constant manner. There are scenarios where Bitcoin network growth could result in both dramatically greater negative impacts, but also dramatically greener overall impacts. The model does not account for Bitcoin's huge sensitivity to non-environmental factors, like national regulatory climate, which would affect mining location and hence emissions; massive Bitcoin price fluctuations, and their impact on demand, etc.
In fact, the price of Bitcoin tracks most closely to its energy demand, reinforcing the correlation between profitability, security and energy consumption. One recent study systematically assessed the link between demand for Bitcoin (which translates to Bitcoin price) and environmental degradation, and found that the link was statistically causal. A further study took a different approach to assess the correlations between Bitcoin market conditions and Bitcoin energy consumption, and likewise found an unmistakable correlation.
This suggests that our prediction of the long term magnitude of Bitcoin's environmental impact is likely to align with our assessment of its long term financial prospects. If we are bullish about its economic viability, we are bearish about its environmental impact; if we are bearish about its financial prospects, we are bullish about its environmental impact, in a pretty linear fashion.
Mining equipment efficiency gains have been touted as a moderating factor, but the last century of hardware efficiency improvements across ICT is a pretty strong predictor of likely rebound effects, meaning that, in a Proof-of-Work system like Bitcoin, I don't believe hardware improvements will likely result in net environmental gains, and could well result in accelerated net emissions.
Which is to say:
If you believe Bitcoin will be massively successful, massively adopted, and transform the way society structures its financial life and much beside... then yes, Bitcoin is likely poised to be environmentally catastrophic.
If you believe Bitcoin is an over-hyped artefact of the pilot stage of blockchain innovation, a gambler's dream (or addiction) that will be left behind by different, better tech and future regulation, then Bitcoin is indeed a massive, painful, costly environmental waste: but not an environmental disaster.
If you think the answer lies between, for instance predicting that the cycle of peaks and troths will continue, and that it may eventually be left behind, but that it won't be quick, and it will probably be much bigger by then: then Bitcoin merits serious worry and environmental advocacy, within the Bitcoin community and in the regulatory sphere.
Could Bitcoin be powered by renewables?
While it is true that currently Bitcoin runs on a typical mix of fossil fuel and renewable power, the case can certainly be made that it would be conceivable to run most or all Bitcoin mining on renewable energy.
Examples have already been given of grid participation schemes, whereby Bitcoin miners are paid by the tax-payer to mine outside of peak times, and in target normally curtailed, surplus energy. In some of these schemes, the focus is exclusively on renewable energy.
With the right incentives, Bitcoin mining equipment could be co-located with renewable energy sources at scale, powered significantly or even exclusively from surplus renewable energy. This has the added benefit of stabilising the grid, an issue that will grow in importance as the share of renewable electricity grows, meaning the potential for scale will only grow with time. Having said that, it is important to emphasise that powering Bitcoin mining on renewable energy is not enough to achieve an environmentally positive impact.
Counter-intuitively, when a Bitcoin mine purchases non-stranded electricity from existing renewable sources, it does not automatically reduce emissions. This is because to balance supply and demand, many national grids replace each additional unit of electricity demand from renewable sources with coal and natural gas equivalents. It is now understood that there is not a one-to-one equivalence between fossil fuel energy and renewable energy in emissions displacement, so you need extra renewable energy to displace the same amount of fossil fuel emissions.
Consequently, there are only two main ways to ensure that Bitcoin mining powered from renewables would result in zero direct emissions on the main electricity grid:
Using surplus renewable electricity that would otherwise be curtailed by the grid.
Constructing or contracting for new renewable electricity sources to power mining
An alternative, complementary approach to the latter involves linking Bitcoin's distributed mining network, to the smaller but steadily growing distributed renewable power network (small-scale solar and wind generators in homes, offices, streets, fields and the like), which currently has limited or no mechanisms to harness or sell their surplus energy.
This general concept, evocatively floated by Nurminen et al. would seem to be a close fit for Bitcoin mining running on spare renewable energy. Examples of this approach already exist. One promising variation is the company Soluna, in Morocco, which is researching how to finance off-grid renewable energy projects with Bitcoin mining. Where off-grid projects are too small and too far to be connected and sell energy to the electricity grid, they can monetise their local renewable power generation via Bitcoin mining as a way of financing capacity growth until they can integrate into the national power grid.
The largest-scale experiment in distributed generation to power Bitcoin was in China between 2014-2021:
When the first group of bitcoin miners arrived in Sichuan around 2014, the sites they chose for bitcoin factories were near small hydropower stations that did not connect to the national power network... For the bitcoin miners, the power price of such offline stations is lower than the power price sold online... The arrival of the bitcoin factory ...made some small hydropower stations profitable.
Addiction to Power: Infrastructure and the making of Bitcoin mining zones in China and the United States
At its peak, China dominated 75% of the global Bitcoin mining infrastructure, and in the summer months when rain is plentiful, most of it was powered by these small renewable hydro-electric plants. China’s winters are arid, and solar and wind farms don’t produce a steady enough supply to run mining operations around the clock, so miners often turned to coal. This put China's trajectory toward Net Zero in danger, leading, together with grid load and economic issues, to the 2021 crackdown that finally stopped the majority of Bitcoin mining in China.
If one could moderate or exclude fossil-fuel-powered Bitcoin mining, with effective displacement strategies, the potential of similar but more targeted approaches would be significant. Given the large number of small-scale Bitcoin investors, network effects and incentives such as subsidies could potentially incentivise and finance a significant expansion of distributed small-scale renewable energy infrastructure, along with more sophisticated industrial operations in the style of Soluna or Chinese hydroelectric miners, ensuring Bitcoin mining runs on surplus renewable energy, or leverages non-residual renewable energy to grow net renewable energy capacity for large ultimate environmental rewards.
What is clear is that this is not primarily a technological issue. The technical means exist or can be realistically developed to run Bitcoin at scale on renewable power. But this is impossible without concerted government action in the form of well-honed incentive mechanisms to make green approaches to Bitcoin mining profitable and expand renewable energy capacity; and enforceable regulation that curbs, disincentivises or impedes fossil-fuel-powered Bitcoin mining.
There is no evidence of this regulatory combination happening anywhere on a national scale, but there is scope for regulatory advocacy and experimentation.
Why "renewable energy" is not enough: the problem of energy demand
So, let us say that we succeed in running Bitcoin on new or stranded renewable energy. Daniel Batten states, almost as as a truism:
"By itself, Bitcoin Electricity Consumption is not the right metric to use, because it cannot give a read on environmental impact. For example, if all that energy were coal, it would be a severe impact. If it were all hydro, the impact would be negligible."
Likewise, Bitcoin's environmental page rhetorically asks:
"If Bitcoin’s energy comes from 70% renewables, is this bad?"
I don't believe that question should be rhetorical, and should in fact be asked in earnest: as we have already seen, the impacts of renewable energy use on environmental outcomes are sometimes unexpected,
Returning to Porter's green Bitcoin dream above, there is no acknowledgement that renewable energy currently powers only 13% of our global energy needs, and surplus renewable energy represents a tiny fraction of that. If all current Bitcoin usage targeted surplus renewable energy, let alone if every use case for carbon-aware computing did the same, the likelihood of perverse effects is high.
An example of such perverse effects could be price inflation. There is evidence from Texas, New York and China that where Bitcoin mining scales up in a locality, local consumer electricity costs also rise, meaning tax payers pay for both, the demand-response subsidies, and a "Bitcoin tax" on their bills.
Another example of preverse effects is the way Bitcoin's electricity demand, as we saw in Texas, can place the grid under strain, renewable energy or not, attracting regulatory attention from Congress. In China too, pressures on the electricity grid led to regulatory warnings and interventions in 2019 that prefigured the final crackdown in 2021. In Venezuela, where subsidised electricity and economic collapse made Bitcoin a financial safe haven, Bitcoin mining spikes led to grid failures and blackouts with 90% of the country being without electric power for several hours, and whole regions losing access to electricity for an entire week. The economic, social and human impact in a country without a functioning social net, was immense.
Porter might argue that this kind of grid pressure is the precise scenario he had in mind in suggesting that Bitcoin's energy demand would accelerate investment in renewable energy infrastructure. The Texas experience shows that indeed Bitcoin has indeed generated interest in further investment in the grid, although it remains unclear how far that interest will translate into hard cash and whether that cash will go specifically to the renewable energy sector. On the other hand, Sulana's example in Morocco shows how Bitcoin can indeed be harnessed to finance the growth of renewable energy infrastructure, particularly for distributed power generation.
Assuming that Porter's dream proved valid, and Bitcoin related grid stresses led to a golden age of investment in renewable energy infrastructure, this brings us back to why Bitcoin's question is worth asking in earnest: is powering Bitcoin on renewable energy bad?
There is a blindspot in this question when used rhetorically, shared by much of the green energy community and virtually all environmental public messaging. Yes, solar, wind and hydroelectric energy are, for all intents and purposes, endlessly renewable.
But turbines, photovoltaic panels, lithium batteries and similar machinery needed to turn renewable energy into usable electricity rely on the extraction of minerals and metals that are not only not renewable, but too scarce to meet projected energy demand.
The results show that proven reserves and, in specific cases, resources of several metals are insufficient to build a renewable energy system at the predicted level of global energy demand by 2050...
We show here that even if the energy system was fully renewable, supply constraints on several elements other than carbon would still compel us to reduce our energy demand.
Enough Metals? Resource Constraints to Supply a Fully Renewable Energy System
Green energy is technically much greener than fossil fuel energy and therefore a key tool in our battle against climate change, but at scale, it is not altogether renewable: it merely shifts the supply chain challenges from fossil fuels to minerals and metals.
This is still preferable, minerals and metals, unlike fossil fuels, allowing for recycling and substitution, reducing overall emissions and improving energy resilience. But it is not a magic formula that spares us from the need to reduce our energy consumption. This means that running Bitcoin on renewables does not render its energy voraciousness moot, even in an all-renewable utopia.
Is Bitcoin worth the environmental impact?
This is a question Bitcoin itself is not afraid to ask, answering in the affirmative. But it does not really try very hard to make its case, barely going through the motions by adducing in evidence Bitcoin's provision of some banking-type services to an unquantified proportion of the unbanked of the world and its contribution to SDG target 10.c to reduce the cost of international remittances.
Hardly a ringing justification for its attributable ~13,000 deaths a year from accelerating climate change. One could argue that Bitcoin's two cited contributions provide more societal value than say, the video-game industry, whose environmental footprint is likely much higher. Or one could got further and point to the tobacco industry's annual emissions of 84 million tons of CO2 for delivering social harm at scale. But such examples are only useful as fodder for whataboutism. They say precisely nothing as to ethical, let alone environmental justifications for mining, or investing, in Bitcoin itself.
Elaborating on the above, the ethical case for Bitcoin as discussed by its advocates may be summarised as follows:
Financial inclusion: Bitcoin can provide a way for individuals who do not have access to traditional banking and financial services to participate in the global economy. By enabling peer-to-peer transactions without the need for a financial intermediary, Bitcoin can provide greater financial inclusion and access for marginalized communities. It can help reduce the cost and complexity of international remittances, which are a critical source of income for many people in developing countries. Bitcoin can also enable micropayments which are not economically feasible with traditional payment systems. This has implications in contexts of extreme poverty or financial exclusion while opening up new opportunities for monetisation and revenue streams in the informal economy and sectors like the arts.
Financial stability, resilience and recovery: Bitcoin shares many of the same characteristics as gold, such as scarcity, durability, and divisibility, so it can provide a store of value that is resistant to inflation and economic volatility. This has led to its widespread use in contexts of mainstream financial collapse, as a hedge and safe haven.
Financial freedom and autonomy: as a decentralized digital currency Bitcoin operates independently of traditional financial systems and government control. This independence and decentralization can in theory provide a greater degree of financial autonomy for individuals and communities, and help to protect against censorship and government interference.
Incentivising the green transition: Bitcoin mining can provide an economic incentive for investment in renewable energy sources, such as solar or wind power, which can help to reduce greenhouse gas emissions and promote sustainability. It can help address the issue of massive renewable energy curtailment and waste, mitigate impacts of fossil fuel generation, and be deployed as a carbon capture mechanism. As summarised by Daniel Batten:
As we have seen already, there are many nuances to each of these claims, but for the sake of argument, let us grant every one of the above benefits.
The question arises: is Bitcoin the best way to achieve these outcomes?
There are a host of blockchain alternatives, which are delivering or could deliver the very same goals. There are also non-blockchain alternatives that could step into use cases pioneered by Bitcoin, such as grid-participation for carbon-aware computing as a demand response mechanism. So granted the above ethical benefits, why Bitcoin and not some alternative?
On the side of Bitcoin, it is far bigger than all the blockchain alternatives in terms of market capitalization, trading volume, and overall brand recognition. This means its potential for network effects, and therefore for achieving the goals above at scale and at speed could be greater, even much greater, than its competitors. Investing in growing Bitcoin as a means of delivering on the objectives above could lead to greater positive impacts faster.
But this is an argument that only holds if the alternatives have a similar benefit/waste/risk profile.
In fact, Ethereum, to give just one example, can approximate most of Bitcoin's key justifications above, although, with less scarcity and higher transaction costs, it may be less compelling than Bitcoin as a value store or financial inclusion mechanism. But unlike Bitcoin, Ethereum is designed as a software building platform, in addition to its functionality as a crypto currency. This means that its potential beneficial uses include but go well, well beyond Bitcoin's financial focus.
It is true that there are mechanisms now for building dapps on top of Bitcoin, but this is not a use case that has reached scale, or is natively suited to Bitcoin, unlike Ethereum and many more alternatives. However, it is entirely within the realm of possibility for this dimension to expand within the Bitcoin ecosystem, and take advantage of the much greater network effects.
More significant is the fact that Ethereum has moved from a Proof-of-Work to a Proof-of-Stake consensus algorithm, dramatically reducing Ethereum's energy intensity compared to Bitcoin, so that roughly similar benefits could be achieved for a fraction of the energy costs, and more importantly, without comparable perverse incentives toward energy consumption and demand, or the overwhelmingly wasteful computation.
This latter point is even more significant outside the blockchain. Bitcoin has pioneered compelling models for using computation to consume stranded renewable energy and serve as a demand response solution to growing grid instability from intermittent renewable power supply. But the compute itself is almost entirely pointless, described as a puzzle saving game in which most attempts amount to nothing. And as we have established, it brings with it an intrinsic energy voraciousness whose risks and consequences do not go away when powered by renewables.
What if that same compute time was devoted, not to hashing algorithms, but to societally meaningful computing problems, and did not imply an inseparable link between profitability, security and energy consumption?
As an example, there is an ongoing project aimed at [discovering causal relationships among human genes to improve drug repositioning](A Computing System for Discovering Causal Relationships Among Human Genes to Improve Drug Repositioning). Instead of running on a single supercomputer, it is distributing the compute task across a huge network grid of small computers, and has raised the possibility of being able to power this network from distributed renewable power generation. If projects such as these, or other volunteer distributed computing projects could be repurposed to run as demand response mechanisms, the benefits could be planetary. The challenge is economically incentivising such uses, although there are initiatives already offering potential Proof of Concept, such as Gridcoin, Curecoin and Foldingcoin. A recent review of similar "added-value" innovations has identified an expansive horizon beyond Bitcoin's trudging consensus algorithms.
So is Bitcoin worth the environmental impact?
In a rare and unlikely scenario where all its potential ethical benefits are being harnessed, and its very serious risks and costs mitigated, one could definitely make the case for Bitcoin's ongoing use and expansion, or at the very least, place it much, much lower in the priority industries to address from an environmental standpoint. But even in this idyllic setting, it seems unlikely that Bitcoin is worth its environmental impacts in comparison to alternative technologies.
When taking all factors into account, the only advantage of Bitcoin is its first-mover advantage and market dominance, enabling greater scale and faster expansion through network effects. But this becomes a massive liability in the likely prevalence of Bitcoin implementations in which negative societal impacts match or exceed positive ones.
In closing, we can derive four key insights from the current state of the art:
- Bitcoin is not currently the environmental catastrophe its most vociferous detractors portray.
2. It is nevertheless environmentally costly and seriously impactful; carries perverse incentives that hardwire energy hunger into its model in an unsustainable way that is not solved by renewables; dedicates almost all its electricity to wasteful computation; and is a poorer instrument in the round to achieve its recognised potential societal benefits than many existing alternatives.
3. This should not blind us to the value of Bitcoin's innovations in the area of carbon-aware computing and methane carbon capture at scale, and its current potential, in circumscribed and carefully designed implementations, to advance the environmental agenda in specific local contexts.
4. Bitcoin can serve, within these very narrow parameters, as a design template that could be adopted and adapted by better, more beneficial and less harmful technologies that can substitute and enhance Bitcoin's current positive applications.