Sept/Oct 2007

Going clean – New technology makes coal greener

By H. E. Robinson

As noted in George White’s article, "The new face of coal," clean coal technologies are pointing to a strong future for this long-time source of energy. The science and technology is proven, and applications are being found. All indications suggest we’ll be seeing the development of coal projects, such as CO2 sequestration and coal gasification, growing in the near future.

Paul Clark, president of Ripley Canyon Resources Ltd. and a veteran in the coal industry with over 30 years of experience, said, “Coal is ubiquitous in the world; it appears almost everywhere and that is why we turn to coal [as an energy source]. There is more energy in coal in the world than there is in oil.”

Coal has played an important role in development. It is a widely distributed resource, fuelling industrial development in many countries. Most developed nations have built their economies on coal. The relative availability and abundance of coal has made it a reliable resource for centuries. It is also an affordable source of energy, costing less than US $2.00 per GigaJoule (GJ). These factors ensure that coal will remain a valuable resource as the demand for energy increases.

Clean Coal Technology (CCT) presents a more efficient and ‘green’ way to use coal by recycling by-products and reducing the emissions of carbon dioxide (CO2). Several examples of clean coal technology are oxy-fuel combustion, amine scrubbing (the use of amine compounds to isolate CO2), and coal gasification. Although these methods use different approaches, they all achieve the same outcome, which is the production of energy while emitting a CO2 gas that is relatively pure and can be easily captured for storage, thereby preventing emission to the atmosphere. The Canadian Clean Power Coalition determined that oxy-fuel combustion and the use of amine scrubbers are expensive processes that also use more energy. This results in a reduced efficiency that in turn means more coal has to be processed in order to produce the same amount of output. A more effective option for clean coal technology is coal gasification, which has enormous potential, particularly in Canada.

Alberta sits above some of the largest coal and oil reserves in the world. Maximizing the efficiency of coal processing can free up resources such as natural gas for commercial and export markets. Gasification involves heating up a coal feedstock at high temperatures and pressure, in the presence of water in the form of steam.

In the process, synthesis gas is produced, which can be used as a natural gas substitute. Further processing can produce high-purity hydrogen (H2), which has applications for upgrading bitumen to synthetic light crude oil. CO2 is still produced but it is concentrated in a way that makes it relatively easy to capture and store in the earth’s crust rather than allowing it to be emitted into the atmosphere. Such CO2 can also be used to enhance the recovery of oil from previously depleted oil wells.

“There is a tremendous interest in gasification and there are numerous carbon-based materials available for gasification in Alberta,” explained White. “[One] can gasify liquids such as bitumen or bitumen residuals, which is being considered by some heavy oil processors; [one] can gasify the petroleum coke produced as a by-product of bitumen synthetic crude; or [one] can gasify coal. All these feedstocks have different characteristics and properties that determine their ease of gasification. Coal is cheap, abundant, and available in large quantities throughout the province where H2 is needed. Our research and development has demonstrated that Alberta sub-bituminous coal is an ideal candidate for gasification.”

“In Alberta, we not only have all the industries that need hydrogen for feedstock, but we have the Western Sedimentary Basin, which provides a vast storage for pure CO2,” added Clark.

The technology involved in coal gasification is not new. About 200 years ago in England, the gas produced by gasification was called ‘town gas’ and was used for lighting and heating homes in London, resulting in a technological highlight of the day. However, town gas was relatively expensive, and was ultimately replaced by natural gas in the mid-1950s. During World War II, the German government used a gasification process called ‘Fischer-Tropsch’ to turn coal into gasoline and diesel fuel. South Africa began using coal gasification methods during colonial development, as the country is rich in coal but limited in petroleum resources. The embargo on shipping to South Africa during Apartheid solidified the use of coal gasification as there was no other alternative fuel source. It has been very successful (South Africa produces 160,000 bbl of oil per day from coal) and is still heavily relied upon to this day.

The conventional processes of generating electricity from coal are now much more efficient than they were last century. High demand, increasing energy prices, and environmental concerns have driven the development of new technological methods that make every new coal plant more efficient than the previous ones. The development of coal gasification technology represents a step change in this advancement and because of greenhouse gas issues, has received renewed interest in the past two decades. Gasification is the only current technology that will have the ability to significantly reduce the amount of greenhouse gases released into the atmosphere from fossil fuels. Reduction of greenhouse gases is the key motivator in seeking clean coal technologies. “The emphasis is on reduction of emissions of CO2 into the atmosphere,” agreed Clark. “[Clean coal] processes and technology all have the ability to capture and store CO2.”

Another factor supporting coal gasification has been the fluctuating prices of oil and gas. Recent increases in petroleum prices make gasification projects economically viable. Coal is relatively cheap and is a local resource so that the price of feedstock can be better controlled. Coal’s abundance and availability means that feedstock prices can be set out in very long-term contracts, thereby reducing the price volatility of the gasification products. Lower carbon products, including hydrogen, synthesis gas, methanol, or even ultra-clean diesel fuel, which also lowers CO2 emissions, are a consequence.

Coal gasification can also play an important role in bitumen upgrading and enhanced oil recovery. Bitumen is a heavy oil that needs to be upgraded before it is refined. The first upgrading process is to add hydrogen to turn it into synthetic crude, which can then be refined into gasoline and other petroleum products. Natural gas has traditionally been used as the feedstock for the production of hydrogen in this process. But natural gas is in relatively limited supply and is subject to price fluctuations. Substituting a H2 source produced by coal gasification would free bitumen upgrading from swings in natural gas prices as well as opening up the reserves for other markets.

“It is a highly capital-intensive technology but is more attractive when [taking into consideration] the value it brings to bitumen upgrading,” said White. “There is much demand to replace natural gas as a source of primary energy for bitumen production and upgrading. Oil sands projects are based on long-time scales, and yet there is no certainty in natural gas availability or cost 20 years from now. Coal is a cheap and abundant feedstock, there is available technology that is being improved, and we have a desire to reduce the carbon footprint through capture and sequestration.” These factors combined can justify some of the capital costs associated with starting a coal gasification plant.

Clark noted “the biggest roadblock now is the capital cost of building these gasification facilities. People struggle to find ways to lower the capital costs, such as ways to improve technology and have higher efficiency. If natural gas and oil prices start to become volatile again, there would be a lot more activity [in coal gasification projects], but so long as the prices are relatively stable, it is going to be difficult to make these kinds of projects economic.”

Another advantage for gasification is enhanced oil recovery (EOR). During the gasification process, CO2 formed by H2 production is in a pure form, suitable for capture and sequestration. CO2 is captured and injected into declining oil fields, which improves the flow rate of oil. The increase in production from an oil field can be enough to offset the price of carbon capture because, in this process, CO2 has a value. Transport of the gas to an oil field can be difficult, but is not necessarily applicable in Alberta because of the high density of carbon resources. In other words, sequestration opportunities exist very close to CO2 sources. For example, the newly proposed coal gasification plant outside of Edmonton by Sherritt International Corp. (Dodds-Roundhill Coal Gasification Project) is close enough to oil fields to enable CO2 transportation through a pipeline.

White explained “there has always been a desire in Alberta to have an integrated resource development plan where all of the various components of the energy business (coal, bitumen, oil and gas, along with other factors such as technology, infrastructure, people, and processes) all come together to promote optimization of the resources.”

In a public disclosure document, senior vice president of Sherritt International Corporation, Barry Hatt, stated, “The Dodds-Roundhill gasification project represents a key step towards Alberta’s future as a global centre of excellence in innovative ‘clean coal technology.’ Such technology can lead to a critical mass of jobs and intellectual capital with tremendous export potential. This new technology will help preserve natural gas resources for higher value uses and unlock the full energy potential of coal.”

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