Its key finding: even stringent accounting rules generally provide sufficient investment incentives. Numerous programs tie the level of subsidy to the assessed carbon intensity of the hydrogen produced. There is currently a policy debate over which carbon accounting rules are appropriate: Should the renewable electricity used for electrolysis be matched on an hourly basis, or is annual accounting sufficient? “The accounting rules ultimately determine how effective public policy is in achieving industrial decarbonization.” Current EU rules for renewable hydrogen stipulate that, until 2030, a monthly matching of electricity generation and hydrogen production is sufficient.