King County Emissions Inventory

Background

The Emissions Inventory is like the carbon footprint of the entire County; it details how much greenhouse gases were emitted 2019-2020, with historical data from previous Emissions Inventories to put it in perspective. The report is put together by the County, with help from an outside contractor with expertise. It is done every two years, and the latest report, although released in Sept 2022, covers emissions in 2019 and 2020.

What impact did the pandemic have? Total emissions in 2020 were down 15% compared to 2019. Aviation fuel use was down by 40%. Commercial natural gas usage was down by 13%; most of this was due to less usage in commercial buildings, but even residential buildings used less, probably because 2020 was a warmer year. Industrial operations, and the emissions that go with them, also dropped significantly. One other change in 2020, which may or may not be pandemic related, PSE reduced the carbon intensity of their electricity by 25%. These large reductions were driven by changes in behavior.

Geographic Emissions Sources in 2019

The chart below shows sources of GHG emissions for the geographic emissions inventory.

Plan for Reducing Emissions 

The County has emissions reductions goals to meet, and they are 50% by 2030, 75% by 2040, and 95% by 2050, compared to a baseline of 2007. The wedge analysis chart below shows the path to get there, and the role each policy plays. Policies in solid colors are Federal, State, and County policies that are already in place, or in the implementation phase (i.e., they are current enacted law). Policies in dotted colors are policies that the County is projecting could be enacted, and, if they were, the GHG reductions that would result. This is the emissions gap –A the difference between the path we are on now, and the path we need to be on. As part of the Emissions Inventory, there is an Excel spreadsheet that allows you to play with the assumptions and modeling that go into these projections, and as you change them you can see the difference it makes too the emissions reductions. For instance, you can change projected rate of EV adoption, and see what difference that would make, or change the rate at which people update their heating systems to use heat pumps.

Consumption-based emissions sources

This is like a carbon footprint of everyone in the County. It shows higher overall emissions, mostly because we are a relatively rich community who import some of our emissions, and these imports aren't reflected in the geographical emissions.

These emissions are worldwide, and cannot be measured directly. Therefore, there is reliance on modeling. Modeling is based on six key factors: household size, household income, vehicle ownership, home size, educational attainment, and home ownership.

The differences in emissions from the consumption-based inventory can be tracked down to the neighborhood level, as shown in the map below:

As you can see, the amount of emissions vary widely between neighborhoods. There are various factors behind the differences:

• PSE vs Seattle City Light (SCL has clean electricity, PSE does not)

• Vehicle miles traveled (rural/urban divide)

• Size of home

• Income

The report sums it as follows:

Questions

• What can be done to get more frequent emissions inventory updates? Is there a “raw data” partial update that could be done?

• What can be done to get more localized geographical emissions? Seems like electricity & gas usage could be done. Do we have traffic volume data per neighborhood or jurisdiction?

• What was driving the changes in carbon intensity in PSE’s electricity mix?

• Does the vehicle modeling takes into account vehicle types & ages registered in the County? Nationwide the efficiency improvements are balanced by a move to larger SUVs and pickups, but this report cites overall improvements.

• Decrease in on-road emissions in 2020 were only 3%????

• Is there anything that can be done about supply chain emissions at state or local level (e.g., last mile driven)?