California has long been a climate action leader, often adopting policies that serve as models for other states and even countries. The state, which would be the fourth- largest economy in the world if it were an independent country, recently took another major step forward. In December 2022, the California Air Resources Board (CARB) adopted a “Scoping Plan” to guide state policies to meet its targets to cut emissions at least 40% by 2030 (from 1990 levels) and achieve net-zero emissions by 2045.

Following requirements the state legislature enacted, the plan is designed to directly reduce emissions by at least 85% and compensate for remaining emissions through carbon dioxide removal (CDR). The plan encompasses a broad portfolio of emissions-reduction and carbon-removal strategies, including clean power; transportation and building electrification; green hydrogen; capturing and geologically sequestering carbon from cement kilns, power plants and directly from the air; and nature-based solutions.

Although the Scoping Plan has many key features, other aspects will need to be refined as the broad plan is turned into concrete policies and investments. WRI commissioned Evolved Energy Research (EER) to make suggestions for how CARB and other California state agencies can build on the tremendous effort that went into developing the 2022 Scoping Plan by updating key assumptions and analytic approaches. EER published Observations on the Implementation of the 2022 California Scoping Plan in December and WRI provided it to CARB through a public comment during the meeting where the Scoping Plan was adopted.

Here is a summary of some of EER’s important observations:

Findings on Electricity System Decarbonization

The Inflation Reduction Act (IRA) provides powerful incentives for California and other states to build new renewable and other zero-carbon generation over the next decade. The Inflation Reduction Act was enacted after energy system modeling for the Scoping Plan had begun, and the final analysis was not updated to reflect it. Future analyses should fully incorporate the benefits of the Inflation Reduction Act, which is likely to allow even deeper reductions in emissions from California’s electricity system in 2030 and beyond those reflected in the Scoping Plan.

EER also notes that a refined analysis of electricity system decarbonization should include geospatial analysis to identify the best locations for infrastructure — such as solar arrays and transmission lines — and address land use conflicts as early as possible. Furthermore, greater regional integration of California’s electricity system with neighboring states would increase reliability and lower consumer costs but was not considered in detail in the Scoping Plan.

The Scoping Plan assumed a ban on new fossil gas power plants, resulting in the selection of hydrogen-burning turbines for electricity reliability needs. This should be reconsidered given the risk of higher NOx emissions from hydrogen turbines. The Scoping Plan also assumed that remaining fossil gas power plants would be retrofitted with carbon capture and sequestration (CCS) just before the 2045 deadline to reach net-zero emissions. It may be more cost-effective, however, to ensure system reliability by allowing very limited operation of fossil gas power plants without CCS and compensate for those emissions with direct air capture (DAC) or other CDR technologies. Non-combustion options for providing firm capacity, such as long duration energy storage or geothermal power, may also be cleaner and more cost-effective solutions than building hydrogen turbines and retrofitting fossil gas power plants that weren’t designed to incorporate CCS.

Geothermal plant emitting steam vapor in California
Geothermal energy is a source of renewable energy in California, generating 5.7% or 11,116 GWh of in-state electricity in 2021. Photo by Andy Van Horn/Flickr

Findings on Carbon Management

Both CDR and CCS have important roles to play in helping California reach net-zero emissions by 2045 or sooner, but further analysis of how and where these approaches should be deployed will be needed as the state implements the Scoping Plan and SB-905, which requires CARB to establish stringent guidelines to govern carbon capture, removal and sequestration in the state. For example, applying CCS to cement kilns makes sense because the process of cement production produces CO2 regardless of which fuel is used. On the other hand, installing CCS at all oil refineries, as the Scoping Plan assumes, would not make sense because most are expected to retire or substantially reduce their output within a few years as electric vehicles replace gasoline- and diesel-powered cars and trucks.

Rows of trees in California almond orchard
Waste biomass from California agriculture, such as wood, shells and hulls from almond orchards, can be converted into biochar that can be applied to degraded soils or bio-oil that can be injected underground to stabilize empty oil and gas extraction caverns and sequester CO2. Photo by Thank You (23 Millions+) views / Flickr

California’s carbon removal strategy should also examine a wider variety of approaches than those included in the Scoping Plan, such as kelp cultivation, mineralization, and converting waste biomass from agriculture and wildfire risk reduction treatments into biochar or pyrolysis oil. Although biomass energy with carbon capture and storage (BECCS) is included in the Scoping Plan as a carbon removal strategy, other recent studies suggest that BECCS-hydrogen could play a significantly larger role than envisioned in the Scoping Plan scenario. The location and energy sources for DAC facilities also need further analysis. Significant cost reductions could be achieved by operating DAC and hydrogen facilities as grid-connected flexible loads, rather than assuming they will be powered by dedicated off-grid renewables as the Scoping Plan does.

These suggestions, and others contained in the EER white paper, can help California further refine its world-leading climate policies to produce even better outcomes for Californians and a better model for other jurisdictions to emulate.