DESCRIPTION OF THE TECHNOLOGY
Coal is the most plentiful fossil fuel on Earth and has been used since the age of the cave man. There is enough on the planet to last another 200-300 years (DOE, 2008).
Electricity is produced by coal when it isburned to boil water; the resulting steam is used to move turbines. The problem with coal is that impurities stored within it like carbon dioxide, mercury, sulfur and nitrogen are released into the air with combustion (ACC. DOE, 2008). Today, this has been limited by:
- Washing the coal pre-combustion to remove particles and scrubbing smoke flues clean of this residue. This produces 50% energy efficiency (DOE, 2011).
- Atom separation – heating coal and blasting the coal with steam, breaking it into its molecular parts, allowing them to be trapped. The result is a mixture of carbon monoxide and hydrogen. Carbon dioxide is captured with chemicals called “amines” and, more recently, ammonia (EARTH magazine. American Coal Council). There are several options for dealing with the by-products, two are:
- Gasification (syngas) – burning the resulting chemicals to turn more turbines
- Capture and storage (CSS) – transporting and burying them underground
COAL TO SYNGAS EMISSION REDUCTION/SINK ENHANCEMENT POTENTIAL
Currently, coal is responsible for more than 70% of CO2 emissions produced by power generation (DOE, 2010). Energy emissions account for at least 80% of greenhouse gases emitted by the US. In many current factories, only 30% efficiency is achieved (DOE, 2011). Pacala and Socolow quoted efficiency of coal at 32% and required 2x the electricity at 60% efficiency to create an adequate wedge.
Integrated gasification combine cycle (IGCC) plants are considered the most efficient coal plant around today, but only 6 exist around the globe. These plants use contained processes to limit the release of by-products; they maximize efficiency(70% quoted by DOE, 2011) and allow carbon dioxide to be siphoned off before coal combustion takes place, which aids in capture and storage. However, they are very expensive and must be built from scratch (CBS News).
The American coal council claims that for every 1% increase in combustion efficiency there is a 2.5% reduction in CO2 emissions (quoted as 3% by IEA and 2.5% by ACC). Diluting the syngas, through the IGCC process, allows for NOx emissions as low as 15 parts per million (DOE, 2011).However, each of the cleaning processes require an extra 1/3 of the energy originally required for simply burning, which requires more electricity and thus more water and coal; it is an endless cycle (EARTH Magazine).
Carbon capture and storage (CSS) units can be built on existing plants, but they also lower efficiency of the plant by 10%, making the option financially challenging (IEA). Pacala and Socolow note that this technology could prevent 90% of carbon emission from coal plants from entering the atmosphere, but also recognize that the future will require much more energy, an amount that no current coal plant on Earth can produce. The largest synfuel facility on the planet produces 165,000 barrels a day, they claim that 200x that amount will be needed in 2054. Additionally, locations for storage are politically difficult to attain and the success of such a program is questionable (NRDC). IGCC plants are built from the ground up with efficiency as their main function, allowing carbon dioxide and other harmful pollutants to be captured without sacrifice to the rest of the system. At the moment, nothing already constructed can compete.
ASSESSMENT OF GLOBAL ADOPTION
At this point, it is not economically viable for a private or public entity to build IGCC plants. The US had considered building one, but the recession forced the federal government to move it’s funding into carbon capture retrofitting on current coal plants (EARTH Magazine). The IEA predicts that as regulations on carbon capture increase the incentive to build IGCC plants will grow (IEA. CBS News.). By making CSS a requirement they predict that the embedded efficiency of an IGCC plant will make it a better choice, when compared to current scrubbing operations. They suggest that efforts must come from cooperation among energy producers and innovators, clarity in policy and incentives from federal governments (IEA).
In February 2010, President Obama challenged the federal government to create a plan for cost-effective CCS within 10 years, including plans for at least 10 commercial demonstration plants nationwide by 2016. He created the Task Force on Carbon Capture and Store (DOE, 2008 and EPA collaboration) to address his request. For now, CSS is the major energy focus for our current administration. $4 billion from the federal government has been combined with $7billion in private investments for development (DOE, 2010).
France, the UK and Australia have all passed legislation that will not allow the construction of new coal-fired plants that are not CSS ready. China has begun a project to build its first IGCC plant and Australia has one in the works (IEA). Unfortunately, China is also building new coal plants at the rate of one per week (CBS News).
History of coal production, Department of Energy (2008):
Cleaning Up Coal, Department of Energy (2010):
Gasification Technology R&D, Department of Energy (2011):
Engineered fuel technologies, American Coal Council:
Power Generation from Coal: Ongoing Developments and Outlook, IEA:
Carbon capturing from coal plants: Is it feasible? EARTH Magazine:
Powered by Coal, 60 Minutes, CBS News:
Natural Resources Defense Council (NRDC), Testimony of Antonia Herzog to the Committee Hearing on Coal Gasification, 2007: