by Henry Robertson, MO Chapter Energy Chair
It’s hard to write about energy without landing you in an alphabet soup, but I’ll try to keep the acronyms to a minimum. When it comes to “clean coal,” there are two that keep cropping up: IGCC and CCS.
IGCC stands for Integrated Gasification Combined Cycle. In an IGCC power plant coal is not burned but chemically converted into a synthetic gas (syngas) that generates electricity in a gas turbine. The waste heat is then used to create steam in a heat recovery steam generator (HRSG—oops) and the steam powers turbines for a second round of generation; hence “combined cycle.” IGCC uses the energy in coal with an efficiency of 3639% compared to 33% in a pulverized coal (PC; sorry) plant. There are a few cutting-edge ultrasupercritical PC plants in Europe, and the coal and utility industries say they can work this technology up to 50% efficiency. IGCC is better than PC for most pollutants except volatile organic compounds (VOCs; I give up), which contribute to ozone and smog; I’ve seen conflicting statements about which technology is better at curbing mercury pollution.
These advantages aren’t exactly overwhelming, and an IGCC plant costs at least 2025% more to build than an equivalent PC plant. Gasification has long been known in the chemical and petroleum industries but has yet to be built at commercial scale for power generation. A number of plants are in the permitting process; one project in Minnesota was recently set back by an administrative decision.
So what’s the attraction? It’s being touted as “clean coal” technology because IGCC works better than PC with CCS.
A decent burial?
CCS is carbon capture and storage; you could add a second S for sequestration and call it CCSS. We could keep merrily burning coal for our electricity if we could keep the CO2 (Carbon Dioxide - global warming gas) out of the atmosphere by putting it back where the carbon came from—underground . If CCS doesn’t work, it’s either no more coal or we cook the planet. The stakes are that high.
CO2 has to be captured from the waste stream, stored on-site, piped to a secure geological formation, and sequestered there forever. IGCC has a big advantage over PC at the capture stage. The syngas consists of carbon monoxide and hydrogen which, when reacted with steam, yield CO2 and more hydrogen. The CO2 can be chemically separated from this concentrated stream of gases.
In a PC plant CO2 has to be captured from the flue gas going up the stack, where its concentration is 1012% at best. Amine absorbent binds with the CO2 and then is separated from it in a regenerator. Incorporating CCS into a power plant is reckoned to cost $30$70 per ton of CO2, according to a Stanford report in Science Daily. The federal Department of Energy puts the cost of capture with current technology at around $150 per ton of carbon, “much too high for carbon emissions reduction applications” (maybe this refers to retrofitting an existing plant). My faith in statistics is fading, but any way you look at it, CCS is expensive. A mid-sized power plant can emit 7 million tons of CO2 a year.
For a technology that’s supposed to be the salvation of coal, CCS is not only pricy but unproven. The first pilot project to capture CO2 from power plant flue gas started up in Denmark in March 2006. Howard Herzog, who led an MIT study into The Future of Coal, says CCS is still in the research phase and will need $1 billion a year for over 10 years to get it going.
Another shortcoming is that the capture process takes some of the electricity generated at the plant, reducing the efficiency of IGCC by 19% and of PC by 24%, according to Herzog.
Then there is the problem of what to do with the stuff. The only application that promises a profit is enhanced oil recovery (yes, that’s EOR)—pump CO2 into an ailing oil field and it will boost production. This is being done on a modest scale in an arrangement between the Great Plains Synfuels Plant in Beulah, ND and the Weyburn Oilfield in Saskatchewan. I have one tiny objection to make: how does pumping more oil help solve global warming?
I usually trust the Intergovernmental Panel on Climate Change, and they say there’s no shortage of geological storage for all human-produced CO2 with high confidence that it would not leak. Leakage would be a problem because CO2 in concentrations above 30% is lethal. A natural CO2 leak at Lake Nyos in Africa killed 1700 people in 1986.
CO2 is acidifying the oceans, and it could do the same to groundwater, posing the risk that toxic heavy metals like lead could leach into drinking water supplies.
Name your price
So what price do you want to pay for electricity? You can pay, for the time being, for business as usual (BAU, of course)—ever-increasing amounts of coal-generated electricity to light cavernous houses and run car-sized refrigerators, big-screen plasma TVs, video games, 24-hour Internet, and every appliance and power tool ever devised by profit-driven ingenuity. As an unbilled extra you get global warming, up to and including the extinction of the human species.
At a substantial add-on price you can get “clean coal.” They’ll stash the CO2 under the floorboards. I would be digressing if I mentioned the costs of the high-energy life that aren’t reflected on our utility bills, such as resource extraction, pollution, waste disposal, and the dirty, tedious and underpaid labor of the poor-country workers who kindly toil for our convenience. Maybe they really are better off than in their ancestral villages, but if we are to avoid the worst of global warming they absolutely must not be allowed to share in our resource-profligate lifestyle. To let them prosper, we must stop hogging the energy.
To replace fossil and nuclear electricity with renewables we’d have to blight great swaths of landscape with wind farms and solar arrays. For the times when the wind doesn’t blow or the sun doesn’t shine we’d have to overbuild to make up for the loss of steady base load power or develop new technologies to store power for use when it’s needed. Apart from that, wind power is now cost-competitive with coal, but solar is still much more expensive even than nuclear.
Renewable energy is great, but it comes in third behind energy conservation and energy efficiency. Conservation is number one. The cheapest, easiest and most environmentally benign way out of the energy and climate crises is simply to use less energy.