New Delhi, India

Climate groups have claimed that altering codes can reduce bitcoin energy consumption by 99 per cent as a campaign called Change the Code Not the Climate.

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The campaign is coordinated by the Environmental Working Group, Greenpeace USA, and several groups battling bitcoin mining facilities in their communities.

An obstacle to large-scale bitcoin mining is finding enough cheap energy to run the huge, power-gobbling computer arrays that create and transact cryptocurrency. 

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Bitcoin mining, in simple terms, is the process by which a network of computers checks and validates a block of transactions that then get added to the blockchain. Miners get rewarded for completing a block.

Bitcoin miners unlock bitcoins by solving complex, unique puzzles. As the value of Bitcoin goes up, the puzzles become increasingly more difficult, and it requires more computer power to solve them. Estimates on how much energy Bitcoin uses vary.

It's an expensive business, though, requiring not just sophisticated and fast "rigs" costing upwards of $10,000, but also a huge amount of power. And it's getting pricier.

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The seven-day average of total mining cost per transaction validated has fallen to $176.8 from a record $235.57 hit in May last year, data from blockchain.com shows.

"As more miners join the network, each individually earns fewer bitcoin. This is because network difficulty increases in order to slow the issuance of new bitcoin," said Joe Burnett, analyst at infrastructure and mining firm Blockware Solutions.

Also see | How much tax is imposed on cryptocurrency in different countries worldwide?

Waning mining profitability is also hitting the broader market because some institutional investors, who are unable or unwilling to invest directly in cryptocurrencies, instead buy shares of listed miners or ETFs that track miners as an alternative way of gaining access to the young industry.

Some of the pressures on miners flow from bitcoin's inherent structure. The decentralised blockchain was created anonymously with a final limit of 21 million coins, of which nearly 19 million has already been minted.

It takes around 10 minutes to mine one block and the reward for miners, who currently get 6.25 bitcoin per block, is halved about every four years.

"There could be one miner or a million, it doesn't change anything. There's only one block and a set number of bitcoins issued," said d'Anethan at Amber Group.

“This is a big problem. In part because of where the industry stands now but also because of our concerns about its growth,” said Michael Brune, campaign director and former executive director of Sierra Club.

“Coal plants which were dormant or slated to be closed are now being revived and solely dedicated to bitcoin mining. Gas plants, which in many cases were increasingly economically uncompetitive, are also now being dedicated to bitcoin mining. We are seeing this all across the country,” said Brune.

Brune added: “It’s particularly painful to see this in the electric sector because that is precisely the place where the US has made most of its progress in the last decade,” he said. 

''There’s no way we can reach our climate goals if we are reviving fossil fuel plants.''

(With inputs from agencies)