Carbon Wedge Analysis


The Carbon Wedge Analysis is a way of presenting the effects various policy actions have toward meeting the Thurston County region’s greenhouse gas emissions reduction goals. Essentially, different policy actions help fill the ‘wedge’ between the ‘no action – baseline’ trajectory, and the targets. Each slice of the wedge represents the emissions saved by taking a specific policy action.

Some policy actions are fairly discrete, such as the updated Washington State Energy Code. Others are defined more broadly. For example, the analysis examined a “deep decarbonization pathway” for Washington’s electricity sector that could result from a range of state, regional, and national policy actions. It also examined the effects of increased adoption of electric vehicles (EVs), which could be achieved through a similarly broad set of local, state, and national policies and incentives. More details on each action and the analysis can be found in the assumptions documentation (link to documentation under More Information)

The consultant team ran a few different scenarios of policy actions, including two alternatives for the mix of sources for electricity generation, and three scenarios for electric vehicle (EV) adoption. A full description of each of the policy actions can be found under More Information.

Climate Wedge Scenarios

All scenarios contain the following policy actions:
  • Electricity generation meets Washington Renewable Portfolio Standard over time
  • New buildings follow Washington Energy Code
  • Vehicle fuel economy meets U.S. Corporate Average Fuel Economy (cafe) standards over time
  • After 2035, new buildings follow a Washington Energy Code extension to achieve net-zero energy for new buildings by 2050
  • Vehicle miles traveled is reduced consistent with regional targets occurs over time
  • Fuel efficiency meets a Low Carbon Fuel Standard
As shown in the table below, scenarios vary based on two factors:
  • Sources of fuel for Electricity Generation (two alternatives)
  • Electric Vehicle market share (three alternatives)
Actions effect on each other. For instance, the high scenario for electric vehicles is less effective when electricity is generated by carbon-intense sources.