US greenhouse gas emissions from the energy sector are going to stay below their 2005 peak for the foreseeable future, thanks to more efficient energy usage and increased use of lower-carbon energy sources, says the Energy Information Administration (EIA).

The projection is in EIA’s preliminary outlook to 2040, the first agency analysis to project beyond 2035.

The US emitted about 6 billion metric tons (MT) of carbon in 2005, EIA Administrator Adam Sieminski, releasing the outlook in Washington, DC, earlier this month, but emissions dropped markedly in the recession. While economic recovery is projected, particularly after 2014, carbon emissions are expected to stay relatively flat.

Sieminski said that, under current laws and trends, emissions will hit only 5.45 billion MT by 2020 and 5.69 billion MT by 2040 as the economy becomes less energy- and less carbon-intensive.
“The population will grow by almost 30%, but energy use will grow only about 10%,” he said.

Sieminski noted that a goal from international climate talks is a return to 1990 emission levels, which in the US case is about 5 billion MT. “It wouldn’t take a huge change in assumptions” to get US emissions to that level, he said.

EIA analysts see several factors stunting carbon emissions’ growth and making the economy more energy efficient.

One factor is continuing technology advances, reflected in rising auto and truck efficiency standards, efficiency gains in all kinds of appliances and motors, and switching to low-carbon fuels.

The population will grow by almost 30%, but energy use will grow only about 10%,”

That includes “significant growth” in renewables, spurred by state requirements and tax incentives and by increasing fossil fuel costs, said Sieminski. However, renewables are growing from such a small base that they will “still have a relatively modest share” of US energy production in 2040, he said.

Another major factor is fuel switching to natural gas for electric generation, heavy-duty vehicles, and manufacturing. The EIA foresees continued growth in shale gas keeping prices low and enabling rapid growth in industrial use, the key factor in projections of higher manufacturing sector output, said Sieminski.

While federal environmental laws will make a difference in emissions, Sieminski said “the key driver” in increased natural gas use remains the relative price of natural gas compared to coal in the electric sector and oil in the transportation sector.

Switching from coal to natural gas in the electric power sector will continue as more than 30 gigawatts of older coal plants are retired this decade, but coal will make something of a comeback after the least efficient plants are out of the fleet, Sieminski said. EIA analysts see operators of the remaining coal plants using them more intensively after costly environmental retrofits.

In transportation, use of liquefied natural gas (LNG) for heavy-duty trucks like 18-wheelers is increasingly attractive given the wide price difference between LNG and diesel, Sieminski said, and other substitutions of LNG for diesel look possible. He cited long-haul railroad trains and marine transports like barges and tankers as vehicles that could make the switch economically without waiting for huge technology development.

Fueling infrastructure is the biggest challenge for natural gas use in transportation, competing with the extensive gasoline and diesel infrastructure already in place, the analysis says.