According to data from the Energy Information Administration, the electric industry has reduced carbon dioxide emissions approximately 25% since 2005. State mandates, local policy goals, and internal utility policies are calling for further cuts in emissions. To achieve these goals, utilities will have to significantly increase the amount of non-emitting generation in their portfolios.
Wind and solar capacity is increasing every year. Total wind capacity now exceeds 100,000 megawatts, more than double what it was in 2011. The U.S. has more than 40,000 MW in utility-scale solar capacity and nearly as much installed distributed solar. Together, wind and solar account for 63% of utility-scale capacity currently under construction.
Public power utilities are in the mix as well. Because public power utilities cannot claim the investment tax credit for renewable generation, most choose to add renewable generation through power purchase agreements. According to a recent American Public Power Association survey, public power utilities have approximately 10,000 MW of wind and solar in their portfolios and at least 6,000 MW of planned additions in the coming years.
The pathway to achieving further carbon reductions is more affordable and operationally achievable if hydropower and nuclear are included in the mix. All forms of non-emitting generation account for over 40% of total U.S. generation, and hydro and nuclear account for three-quarters of this generation. Several states have more than 50% non-emitting electricity generation already, including nuclear, hydro, and other renewables. New developments in nuclear technology, including small modular reactors, have the potential to increase the amount of nuclear capacity in the future.
Although hydropower and nuclear are integral to getting to a clean energy future, some states place limits on the size or type of hydro capacity that counts toward state renewable portfolio standard mandates, and some exclude nuclear from goals. Excluding these and other non-emitting forms of generation — including carbon capture, utilization, and storage — makes it much more difficult and costly to achieve an emissions-free portfolio in the future.
Even if all forms of generation are included, it is still challenging to get to 100% non-carbon-emitting energy, as the costs increase appreciably the closer one approaches this level. Adding more wind and solar will require more transmission upgrades, as wind and solar capacity is generally not sited near population centers. Since wind and solar are intermittent forms of generation, they also require backup power generation, such as natural gas and battery storage, with the latter technology not yet robust enough to provide significant utility-scale backup reliably.
Another issue is that electricity only accounts for 28% of all carbon emissions nationally. Other sectors of the economy — including transportation, agriculture, industrial processes, heating and others — account for the rest and might be more difficult to decarbonize. Electrification — especially in transportation, home heating, and water heating — can help reduce overall emissions but will require development of new technologies to significantly decarbonize.
The electric industry has made great strides in reducing its carbon footprint, and projections indicate we will go even further in the future. In order to achieve carbon reduction goals, policymakers must give utilities the latitude to choose the right resource mix. Furthermore, policymakers will have to consider whether 100% emissions-free goals are attainable in the first instance given reliability and affordability priorities.
. See, for example, Pacific Northwest Low Carbon Scenario Analysis: Achieving Least-Cost Carbon Emissions Reductions in the Electricity Sector. Energy and Environmental Economics Inc. Project Team: Nick Schlag, Arne Olson, Kiran Chawla and Jasmine Ouyang. December 2017; Energy Futures Initiative, The Green Real Deal: A Framework for Achieving a Deeply Decarbonized Economy, August 2019; and Optionality, Flexibility & Innovation: Pathways for Deep Decarbonization in California, May 2019.