What does California's proposed buffer account mean for carbon storage under the Cap and Invest Program?

California's regulator ARB on Tuesday proposed letting covered entities cut their Cap and Invest Program obligations by storing captured CO2. The catch is a new insurance layer. Entities would be required to submit allowances to a buffer account that acts as a safeguard if stored carbon leaks back into the atmosphere.

The proposal addresses a long standing concern with permanence in carbon storage accounting. Crediting a reduction today for CO2 that is meant to stay underground for centuries creates a liability if that storage fails. A buffer account pools that risk by holding back a portion of value, so that reversals can be covered without unwinding the compliance position of the individual company.

For compliance teams at covered entities, the mechanics matter more than the headline. Submitting allowances to a buffer account means the benefit of storage is not a one for one reduction in obligations. Finance and carbon desks will need to model the net effect once the buffer requirement is applied, and decide whether storage remains economic compared with buying allowances or cutting emissions at source.

The proposal also signals how regulators may treat storage under other regimes. A buffer is a familiar tool in voluntary carbon markets, where registries hold back credits to cover reversal risk. Seeing the same logic written into a compliance program suggests that permanence risk is moving from a registry level concern to a regulatory design feature, which companies operating across jurisdictions should track.

What comes next is the rulemaking process itself. This is a proposal, not a final rule, so details on the size of the buffer contribution and the eligibility of storage projects can still change. Companies with exposure to California should engage in the comment process, since the final design will determine whether carbon storage becomes a workable compliance route or a marginal one.