What if gas continues to be used in buildings?
Buildings comprised 14% of the Northwest’s greenhouse gas emissions in 2019. While the Northwest has a high share of electric heating, approximately 50% of heating energy use is gas. The NZNW Energy Pathways analysis modeled a scenario to examine the impact of retaining gas instead of electricity as a decarbonization strategy for buildings.
The Core Case models rapid electrification of residential and commercial gas appliances, which reach 100% electric sales shares by 2035 in space heating, water heating, and cooking. The Core Case also assumes that sales of both high-efficiency building technology and high-efficiency building shells will reach 100% by 2035 for both residential and commercial buildings and that 100% of stove sales are electric by 2035.
The scenario that retains gas in buildings assumes the same share of gas appliances (heaters and stoves) that exist in buildings today will exist in the future, with gas heating appliances replaced with high-efficiency gas options, reaching 100% sales by 2035. Buildings that already have electric appliances transition to higher-efficiency electric options at the same rate as in the Core Case. All demand-side assumptions in the transportation and industrial sectors are held constant.
The analysis found that:
Since gas appliances are less efficient than electric appliances, retaining gas in buildings results in 11% higher final energy demand across the economy by 2050 compared to the Core Case.
By 2050, retaining gas in buildings drives up decarbonization costs by $4.6 billion per year compared to the Core Case.
Even if heat pumps were 20% more expensive and there were no savings on gas pipeline infrastructure with decreasing gas use, costs are $2.9 billion per year higher by 2050 when gas is retained in buildings.
Northwest peak electricity load (excluding transportation load) grows only 8% from 2021-2050 when retaining gas in buildings compared to over 50% in the Core Case during the same period.
Please see NZNW Buildings Results for a full discussion of the assumptions, modeling, and impact of retaining gas in buildings on achieving net-zero emissions by 2050 in the Northwest.
Energy Use is Higher When Gas is Retained in Buildings
The Core Case finds 30% less final energy demand is required in 2050 than in 2025. When retaining gas in buildings, the drop in total energy use is eight percentage points less than in the Core Case as seen in the visualization below. When looking only at the commercial and residential sectors, rather than all four sectors shown, energy use is 31% higher than in the Core Case because gas appliances are less efficient than electric heat pumps.
Less Electricity is Required When Gas is Retained in Buildings
As seen in the visualization below, retaining gas in buildings uses less electricity overall than the Core Case, which translates into 11% less need for new wind capacity and 19% less need for nuclear by 2030. By 2050, the impact on capacity investments is 3% reduction in wind capacity; 11% reduction in solar capacity; and 61% reduction in nuclear energy.
Retaining Gas Requires More Decarbonized Fuels or Emission Offsets
The increased gas demand when continuing to use gas in buildings must either be met with decarbonized fuels or offset by emissions reductions elsewhere in the economy to reduce emissions according to the same targets as in the Core Case. The visualization below shows the following impacts of the increased need for gas on the Northwest fuel supply when retaining gas in buildings:
Increased use of fossil gas through 2050, which is offset by earlier use of clean liquid fuels and increased carbon sequestration
Increased use of biogas from 2040 to 2050
Electrofuels are produced in greater volumes from 2030 through 2045
Retaining Gas in Buildings Costs More Than Using Electricity
By 2050, retaining gas in buildings costs $4.6 billion per year more than the Core Case. Increased costs include clean fuels production (including electrofuels and biofuels); increased fossil fuel costs, and fuel transportation and delivery costs (including gas pipeline costs); increased direct air capture (DAC) costs; and increased geologic sequestration costs.
The costs that decrease when retaining gas in buildings include reduced electricity grid investments due to lower levels of electrification in buildings and reduced demand-side equipment costs due to the lower cost of gas appliances versus their heat pump counterparts.
While retaining gas in buildings requires less investment in electricity, on balance the technical and economic benefits of using electricity for heating, cooling, and cooking outweigh using gas in buildings. If gas were retained in buildings, investment in clean fuels and carbon sequestration would be required beyond what the Core Case needs.
In the 2030s, recommended actions include: rapid growth in electric space and water heating appliance sales, developing a more granular analysis of where opportunities might exist to retire gas infrastructure, and a geographical analysis of where hybrid systems could be deployed in the coldest Northwest climates.
By 2035, all building appliance sales should be electric to minimize decarbonization costs. In the 2040s, efforts should be made to reduce investments in gas transportation and delivery systems as gas volumes decrease and to decommission gas pipelines where possible. By 2050, Washington state’s pipeline gas supply must be fully decarbonized.
Although the NZNW Energy Pathways analysis shows that electrification of heating, cooling, and cooking is the most economic pathway to achieve net-zero emissions by 2050 for the building sector, there are significant challenges to transitioning off gas, particularly the potential financial impact on low- and middle-income ratepayers, who cannot be expected to bear the transition costs.