Report: Maine must decarbonize transportation and heating to meet climate goals

Maine will need to decarbonize its transportation and building heating sectors to meet newly adopted greenhouse gas emissions limitations, according to Efficiency Maine Trust's final report, Beneficial Electrification: Barriers and Opportunities in Maine.

In 2019, the Maine legislature enacted a series of laws significantly reshaping the state's electricity laws and climate policy, including a doubling of Maine's renewable portfolio standard (RPS) to require 80% of electricity sold at retail to be backed by renewable attributes by 2030, expanded eligibility for net energy billing programs offering enhanced value to participating customers, mandates to procure renewable energy from both large and small distributed generation resources, and the Maine Climate Council law requiring Maine to reduce its gross annual greenhouse gas emissions to at least 45% below the 1990 gross emissions level by 2030 and to at least 80% below 1990 levels by 2050.

The legislature also enacted a law focused on "beneficial electrification", a concept defined as "electrification of a technology that results in reduction in the use of a fossil fuel, including electrification of a technology that would otherwise require energy from a fossil fuel, and that provides a benefit to a utility, a ratepayer or the environment, without causing harm to utilities, ratepayers or the environment, by improving the efficiency of the electricity grid or reducing consumer costs or emissions, including carbon emissions." This beneficial electrification law required the Maine Public Utilities Commission to conduct a transportation electrification pilot program, and required Maine's quasi-governmental independent efficiency program administrator Efficiency Maine Trust to study barriers to beneficial electrification in Maine's transportation and heating sectors.

The Trust released its final report under that mandate on January 31, 2020. In the report, the Trust notes, "Maine has thus far focused much of its GHG reduction efforts on increasing renewable electricity supply and improving energy efficiency." The report cites examples such as the Trust's core work under a state law mandating that electric and natural gas utilities assess their customers in an amount necessary to fund “the maximum achievable cost-effective energy efficiency" through the Trust, as well as the recent expansions to the renewable portfolio standard and net metering programs and the recently enacted long-term contract procurement mandates.

As noted by the Trust, "these policies have significantly decarbonized Maine's electric generation sector". Electric power generation contributed just 7% of Maine’s greenhouse gas emissions in 2017 (down from 9% in 2015), and has shown the greatest percentage reduction in carbon emissions relative to its peak compared to any other tracked sector. In 2018, about three-fourths of Maine's electricity net generation came from renewable sources.

The report further observes that despite the substantial progress already achieved and further progress mandated with respect to electricity, direct fossil fuel use in transportation and buildings continues to contribute most of Maine's greenhouse gases emissions:

Notwithstanding the progress in GHG reduction from the policies mentioned above, there remain significant emissions resulting from direct fossil fuel use in buildings (residential and commercial), transportation, and industry as shown in Figure 3. Maine’s RPS and solar policies have limited direct impact on those fossil fuel emissions for all but the electric power sector. 

Figure 3, reproduced below, shows that in 2017, the transportation sector was responsible for 54% of Maine's greenhouse gas emissions from fossil fuel combustion, with buildings responsible for another 30%, while the industrial sector contributed 9%, and electric power just 7%:

The report notes that three "key electrification technologies" -- heat pumps, heat pump water heaters, and electric vehicles -- "can play a significant role in curbing a large portion of the state’s overall emissions." While the report did not attempt to develop a precise estimate of the number of heat pumps, heat pump water heaters, and EVs required to achieve Maine’s emissions reduction targets, it did project that electrifying 90% of light duty vehicles could mean that over 1.2 million passenger EVs would be registered and operating in Maine by 2050, compared to about 3,000 today, and that electrifying 95% of fossil fuel demand for heating in residential buildings could mean installing well over a million heat pumps and 500,000 heat pump water heaters, compared to about 43,000 and 24,500 respectively today.

The report cites Maine's success to date in promoting heat pumps through the Trust's programming, leading to "the highest per-capita penetration of heat pumps in the U.S., with at least 46,000 installed over the past seven years in residential and commercial settings". But the Trust's report suggests that should be viewed as just the tip of the iceberg, with significant more work ahead in the near term to decarbonize the transportation and building heating sectors.