PayPal is proposing a new initiative to incentivize sustainable Bitcoin mining. The company's Blockchain Research Group, in collaboration with Energy Web and DMG Blockchain Solutions, is suggesting "cryptoeconomic incentives" to encourage miners to use low-carbon energy sources. Under the proposal, "green miners" would be rewarded with special "green keys" and have transactions preferentially routed to them. This would incentivize profit-driven miners to operate with low-carbon sources to gain extra BTC rewards. The proposed solution has been successfully tested with Bitcoin miner, DMG Blockchain Solutions Inc.