If natural gas is a “bridge fuel,” what’s on the other side?
This question kept popping up in recent weeks as a series of reports predicted gas would become a growing part of the global energy mix in the coming decades. Gas, while cleaner burning than coal, still falls short of the low-emissions scenarios envisioned by world leaders, including President Obama.
The solution, according to some experts, is to siphon off and bury the carbon dioxide deep underground using a suite of technologies called carbon capture and storage (CCS). CCS is typically seen as a way to redeem dirty coal, but that view is changing.
“CCS is not a coal technology at all, it is a greenhouse gas abatement technology,” said Julio Friedmann, the leader of the Carbon Management Program at the Lawrence Livermore National Laboratory. “Increasingly people are realizing that the long arc of climate mitigation really does require capture from natural gas plants.”
A viable, but flawed, technology
CCS is ideal for natural gas, Friedmann said, because many of the technologies have already been tested at gas plants. Gas emits a fraction of coal’s sulphur and particulates, which must be removed before the carbon is captured. In addition, he added, markets with a lot of natural gas power (think California) have high electricity prices to begin with, so the additional cost of CCS is more easily absorbed.
CCS actually works – it has been tested at several coal plants and at multiple industrial applications – but it has several knocks against it. For one, it’s expensive. Friedmann estimates current costs range from $80 to $100 per ton of carbon dioxide to retrofit a natural gas plant. CCS also reduces a plant’s energy output because the system needs power to operate.
Critics have also raised concerns about carbon dioxide leaking from CCS projects and contaminating groundwater, pointing to alleged leaks from a site in Saskatchewan. Subsequent studies and experts have refuted the leak claims and Friedmann said uncontrolled leak of carbon dioxide stored underground is extremely unlikely. Still, industry recognizes that the public must be sold on the benefits and safety of large-scale CCS.
Cost a barrier
Perhaps the biggest barrier to a large-scale pilot project has been the capital cost of installing CCS.
CCS has been most successfully used in places where the carbon dioxide can serve a purpose, such as injection into depleted oil wells to goose production, or must be removed for economic reasons. Norway, for example, has been a global leader in CCS, in part because of the country’s tax of $50 per metric ton of carbon makes projects economically feasible.
The oil company Statoil has been removing carbon dioxide from natural gas from the Sleipner field and pumping it 1,000 feet below the North Sea floor for 15 years. Also in Norway, the Technology Center Mongstad at Statoil’s Mongstad refinery will use two different types of CCS technology – chilled ammonia and an amine process – to capture 85 percent of carbon dioxide.
California utilities investigate CCS
Absent a tax on carbon, the U.S. will continue lagging behind in CCS for natural gas plants, though this too is changing.
A coalition of government labs, nonprofits and California utility companies, motivated by a law mandating greenhouse gas emission reductions of 25 percent by 2020, are investigating CCS. Those emissions reductions will have to come from gas plants, which provide about half of the state’s electric power, according to Rich Myhre, a spokesman for The West Coast Regional Carbon Sequestration Partnership (WESTCARB).
WESTCARB has begun a one-year study of the costs and engineering challenges associated with retrofitting California natural gas plants for CCS, Myrhe said. But he conceded that utilities are not yet ready to go ahead with an installation.
As Friedmann, who is involved in the WESTCARB project, said: “The more we look at CCS the smaller the risks look and the better the technology looks. That’s not the same as having solved these problems.”
Article appearing courtesy Txchnologist.