Wissenschaft

Natural Gas Use Is Rising. Is that Good News or Bad News for the Climate?

As another decade ends, change is in the air. Six million protesters took to the world’s streets during September’s climate meeting in New York. School strikes are spreading, and Time named Greta Thunberg its Person of the Year.

What didn’t change much during the 201os was the relentless rise in greenhouse gas emissions. Through our annual release of the Global Carbon Budget 2019, we recently reported that fossil CO2 emissions rose by one sixth during the decade, ending with our estimate for 2019 of 36.8 billion metric tons of CO2 pollution (40.6 billion U.S. tons ±1percent). That’s an elephant’s worth of CO2 pollution—five tons a year—for every person on earth, albeit distributed unevenly around the world.

The best we can say for 2019 is that global carbon dioxide emissions rose “only” 0.6 percent (likely range from minus 0.2 percent to 1.5 percent). That’s a lot slower than the 1.5 percent and 2.1 percent growth in 2017 and 2018. Is it good news, the start of a transition away from fossil fuels, or is it simply bad news, another record year of fossil carbon dioxide emissions?

Increased natural gas and oil use are driving the increase in carbon dioxide emissions and are outpacing slight declines from global coal use. Oil use around the world has been rising steadily at about a percent and a half per year for the last five or six years. Natural gas use is surging at almost twice that rate, aided by the boom in liquefied natural gas (LNG) that is connecting global gas markets. Emissions from natural gas use rose almost 200 million metric tons of CO2 in 2019, and were responsible for two thirds of the global emissions increase.

In the United States and Europe, natural gas is replacing coal in electricity generation. Coal consumption in both regions dropped at least 10 percent in 2019. Coal use in the U.S. is down by half from 15 years ago; 500 coal power plants have closed or are scheduled to. Most of the lost U.S. coal capacity was replaced by natural gas, with additional contributions from renewables and energy efficiency. In the United Kingdom, the birthplace of the industrial revolution, coal-fired electricity has almost disappeared and now supplies only 5 percent of power. In both countries, the replacement of coal by natural gas and renewables is reducing both CO2 emissions and air pollution from particulates, mercury, sulfur and lead—saving lives as a result.

While the U.K. and U.S. have some positive news, emissions are rising in many other places around the world. Oil use continues to climb, and the additional natural gas being burned isn’t replacing coal in electricity generation. Rather, it’s meeting new energy demands for electricity and residential and industrial heating. China burns half the world’s coal. In 2019, its coal use is expected to climb about a percent at the same time its natural gas use grows 9 percent and oil use climbs 7 percent or so. China’s per capita CO2 emissions now equal those of Europe’s.

In some places, natural gas is even replacing low- and no-carbon fuels. Before the Fukushima disaster in 2011, Japan produced almost a third of its electricity from nuclear power. By late 2013, it had closed all of its reactors, at least temporarily. Today only nine of 40 or so Japanese reactors are back to producing electricity. What fuels filled the gap? Natural gas, primarily, imported through more than 30 liquefied natural gas terminals, with additional contributions from coal, renewables and energy efficiency. Japan is one of the world’s most energy efficient countries, and continuing efficiency improvements in other sectors have offset increased emissions in electricity. Still, Japan’s CO2 emissions would have decreased much more if natural gas hadn’t replaced nuclear power.

With natural gas use surging globally at 2.6 percent a year and with increased emissions from it outpacing decreased emissions from coal globally, we need to reevaluate the role of natural gas as a bridge fuel. Where it replaces coal for electricity generation, it’s reducing carbon dioxide emissions and improving air quality. It still produces carbon pollution, though, and therefore slows, but does not solve, the climate problem. Where it’s providing new energy and new emissions—replacing low- and no-carbon technologies or keeping them from being deployed—it is hindering climate solutions.

If the world is going to build thousands of new natural gas plants over the next decade—infrastructure that will run for decades—most of the plants should be carbon-capture–ready or use new technologies to produce their power. This is unfortunately not yet happening. One promising new technology is the Allam cycle, which burns natural gas or other fossil fuels in oxygen rather than air, with carbon dioxide as the carrier gas. An Allam cycle power plant produces almost pure CO2 as a byproduct.

This pipeline-quality CO2 removes the need for CO2 capture in current technologies that use amines or hydroxides to scrub the CO2. The CO2 can then, in principle, be sequestered back underground, like the natural gas or coal it came from. A 50-megawatt Allam Cycle demonstration plant is being built in La Porte, Tex. We hope it succeeds.

Over the last decade (2009–2019), global carbon dioxide emissions from natural gas use have increased 30 percent a year to more than 7.5 billion metric tons. Some of this increased gas use has replaced coal emissions, which also rose 11 percent over the same period. Most of the gas has not displaced coal and is unlikely to do so in the near future. Unless most of the emissions from new natural gas infrastructure are captured and either stored belowground or utilized for renewable fuels, global temperature stabilization at 1.5 or 2 degrees Celsius will be extremely difficult, if not impossible, to reach.

This year’s likely growth in global CO2 emissions of approximately 0.6 percent will be slower than the growth in emissions for the past two years. That’s good news. But growth is growth, and another year and another decade have been lost to record emissions. We remain far from the 7.6 percent annual declines recommended by a new United Nations report. Current trends don’t suggest structural changes are happening that would lead to a peak and decline in global emissions anytime soon.

As we welcome the New Year and new decade, some people will celebrate the good news that emissions growth slowed in 2019. Others will bemoan the bad news that growth is growth, with record carbon dioxide emissions reached yet again. What we need is much more radical news: a steep drop in pollution that drains the emissions glass as quickly as a final champagne toast.

All of the authors are members of the Global Carbon Project, an international group of scientists who track emissions and sinks of CO2 and other greenhouse gases from land, oceans, industry and agriculture.

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