Coal and nuclear provide more than half of the country’s electricity, with the future mix central to the USA’s climate ambitions
By Gerard Wynn
Future US carbon emissions will fall if the competitiveness of coal-fired power plants continued to suffer compared with natural gas, the statistics arms of the Department of Energy said on Monday.
US carbon emissions have fallen faster than any other developed country in recent years, thanks to a shale gas revolution which has put some coal plants out of business.
However, coal-fired and nuclear power plants still together provided 56% of the electricity generated in the United States in 2012, underlining their importance.
The Energy Information Administrationâs (EIA) calculates that carbon emissions will soon continue an upward trajectory as the impact of the shale gas revolution fades, under its âreference caseâ.
In new analysis, however, the EIA calculated what would happen if the competitiveness of coal and nuclear power stayed under pressure.
When faced with declining profitability, plant owners may choose to retire their units rather than make additional investments to keep them operating.
If more coal plants closed than previously expected, then carbon emissions may fall by more than 10% by 2040, compared with present levels.
If nuclear power plant closures accelerated, however, then carbon emissions may rise, as these were replaced partly by gas.
Accelerated closures would be a huge bonus to gas and renewables.
âThe new capacity mix consists almost entirely of natural gas and renewable energy sources,â EIA said.
âNatural gas-fired combined-cycle units are favored because of their low fuel prices and relatively moderate capital costs.â
The EIA described scenarios where coal-fired and nuclear power plants may close faster than previously expected.
Regarding less competitive coal, the EIA study assumed higher coal prices than under its reference case, and rising operating and maintenance (O&M) costs.
Under that scenario, some 110 gigawatts of coal plant capacity closed between now and 2040, compared with 50 GW under the EIAâs reference case. That compares with a total of 310 GW of coal capacity presently.
The EIAâs reference case assumed that O&M costs remained flat for both nuclear and coal.
Regarding less competitive nuclear, the EIA assumed rising O&M costs, and also that no new nuclear power plants would be built beyond those already in the pipeline.
Under the resulting accelerated nuclear retirements, 42 GW of nuclear capacity were retired through 2040, compared with about 5 GW in the reference case.
The assumptions used to simulate less competitive coal and nuclear power were only examples of economic conditions which might cause them to suffer compared with gas and renewables.
Coal would equally be damaged by new carbon regulations such as the wider introduction of carbon prices.