The seminar, hosted by Chewonki Foundation, was a meeting of scholars from Princeton University, Clark University, Harvard, and MIT, individuals involved in Maine and federal energy and environmental policy, and members of the business community who work with carbon capture technology.  Twin River Energy asked Sarah Forbes of Potomac Hudson Engineering to conduct a “Mine to Wheels” analysis of its proposed gasification plant.  The project engineer for the plant also spoke about the proposal.

All of the participants were clear about one thing:  All ecologically sensitive sources must be added to the mix as soon as possible, and most scenarios include rapidly expanding current renewable energy sources of all types (wind, solar, geothermal, hydro), emergent energy sources such as hydrogen and tidal power, cleaner fossil fuel sources that sequester carbon emissions, and nuclear power.  All agree that in 20 years’ time, the energy grid must look very different than the grid looks today.

Overall, the case for carbon capture and storage (CCS) is good; emerging economies are adding dirty coal-fired plants at the rate of one every other week.  Coal is plentiful and cheap, and will remain, regardless of the environmental costs, the fuel of choice for decades to come, especially in the developing world.  If possible, the best thing to do would be to find a way to capture the carbon that emerges from plants and store it underground.  On a small scale, this is technically possible today. 

However, large scale plants have never been tried, and in the last year, nine U.S. plants that want to use this technology have either voluntarily decided it was not economically possible, or have been forced to put their project on hold by regulators.  (see sidebar)

Without any carbon capture, this plant would perform like a traditional coal plant, and the "liquid-coal" diesel that it would produce would have twice as much emissions of traditional petroleum diesel. With capture (and biomass) the diesel would be the same as regular diesel and the power plant emissions would be similar to natural gas plants.  Either way, the use of coal alone is not good enough to stabilize atmospheric greenhouse gas concentrations.
The only way coal can even potentially be used to effect decreases in greenhouse gas concentrations is with a biomass partner.  The use of food stocks, such as corn and soy, are not good partners, because the carbon cost of planting them and raising them to harvest is so high. 

In Illinois, a potential test program consists of a plant, located near the mouth of a coal mine, with arable land a short distance away.  In this scenario, certain prairie grasses are grown instead of corn or soy, and harvested at the end of the growing season.  A certain amount of carbon is stored in the roots of the plants, and remains in the soil, allowing the plant to use this carbon for its own growth in future growing seasons and keeping it out of the atmosphere.  The carbon that remains in the plant roots, and carbon dioxide stored in a deep saline aquifer located directly beneath the plant, offset any potential carbon released to the atmosphere by the processing of the coal and biomass. The ratio of biomass to coal needed for “zero” net greenhouse emission is about 1:4, if credit for the carbon in the roots and soil is “given”.   If not, the ratio rises to about 1:3.

Currently, this test program is a mere thought experiment, however, located where it would be, with the kind of carbon sink needed, this kind of scenario might one day prove to be an important player in the fight to decrease greenhouse gases in the atmosphere.

By contrast, the proposed plant in Wiscasset has none of these advantages.  It is located nowhere near a coal mine; it has no convenient field of prairie grasses growing nearby; it has no potential carbon sink anywhere within 400 miles. 
The proposed gasification plant in Wiscasset plans to use forest product refuse - woody residue left over from the lumber milling process or paper making process.  These wastes would come into Wiscasset from northern forests, adding additional carbon dioxide as they are transported to the coast.  The plant plans to use underground coal supplies, which would come from western Pennsylvania, carried by train and barge, and possibly train again. 

The closest site known for potential carbon capture is the Sable Island oil field, located off the coast of Nova Scotia.  It is possible that further south on the Georges Bank in the Gulf of Maine, a region known well for its rich fisheries and rare whale habitat, might also be a potential site for carbon storage, however it is unlikely that the southern Georges Bank would pass muster from an ecological perspective, since it is a seasonal feeding ground for Right and fin whales and other endangered species.  Both the United States and Canada have agreed to a moratorium on oil exploration on the Bank to preserve the fisheries.

To get the carbon dioxide, under high enough pressure to form a liquid, from the Wiscasset coast to either site would require a pipeline.  The costs of laying such a pipeline would be high, acknowledges engineer Sarah Forbes.  There are currently no plans or negotiations to establish a place to put the carbon.

Despite the assertion by an earlier presenter that coal use without complete CCS would be ecologically unfeasable, it was learned at the end of the seminar that the Twin River Energy project plans to capture only 25% of the carbon generated.  75% would be emitted through the stacks.  And although Twin River has committed to technology that would capture 25% of the carbon, there is currently no way to actually store it anywhere.

Other presenters noted the difficulty of retrofitting coal plants, so the undeniable truth is that the Twin River Energy Center would emit between 75% and 100% of its carbon dioxide over the lifetime of the plant, adding to - not subtracting from - the global warming problem worldwide.

Since the trees from which the biomass stocks will come may or may not be replanted (Twin River has no immediate plans to reseed, although the paper and lumber companies may), the biomass is not a carbon-neutral source in any case.  By comparison, the prairie grasses in the Illinois project would quickly grow back to absorb carbon on a regular basis.  Carbon dioxide is absorbed by plants during photosynthesis; however, after the plants die, the carbon is returned to the carbon cycle in one way or another.  Whether the plant is used in a gasification plant or decomposes on the field or forest floor does not matter.  If a plant is grown to replace the one that is used in industry, well and good.  The cycle is balanced, and the result is a net-carbon-neutral system.  If the plant is removed from the ecosystem and not replaced, the result is a net carbon addition. 

There is currently no way to know whether the biomass stock Twin River plans to use will come from sustainable forest practices or not.  Twin River has repeatedly said that no decisions regarding source of materials, energy partners, water usage, or even transportation of the coal/biomass will be addressed before the November 6 election.

Sarah Forbes’ study, which has not yet been presented for peer review by the seminar participants, including Chewonki itself, may or may not be accurate.  In her findings, she claims that, even considering all the costs of transportation of coal and biomass to the site, the plant would emit slightly less carbon dioxide than a similar natural gas plant with a small amount of oil refining to account for the 11,000 barrels of F-T diesel every day, if ... and only if ... the plant uses 5% or more biomass, and stores 25% of its carbon.

Currently, the carbon storage piece is impossible.  Even if and when that problem is resolved, the Twin River plant will be a net emitter of carbon dioxide for the lifetime of the plant ... and part of the global greenhouse gas problem, rather than part of its solution.