‘Green coal’ is at the forefront of global governmental and scientific agendas in that it could greatly reduce carbon emissions
Having spent two years supplementing decidedly menial developments in furthering clean coal technology, a group of researchers at Ohio State University (OSU) have taken crucial steps towards the technological bettering of clean coal technology.
In February 2013, OSU professor Liang-Shih Fan led and directed a select team of students in reaching a new milestone for clean-coal technology. Fan – having already instigated a number of local environmental initiatives – is Professor of Chemical and Biomolecular Engineering at OSU, as well as being the Director of Ohio State’s Clean Coal Research Facility. Having made the breakthrough, the team hope that “not only can we use America’s natural resources such as Ohio coal, but we can keep our air clean and spur the economy with jobs.”
The discovery – termed ‘coal-direct chemical looping‘ (CDCL) – is a pioneering technology entailing the chemical conversion of coal to heat while safely retaining 99 percent of the carbon dioxide generated. Fan explains that: “In the simplest sense, combustion is a chemical reaction that consumes oxygen and produces heat… unfortunately, it also produces carbon dioxide, which is difficult to capture and bad for the environment. So we found a way to release heat without burning.”
More specifically, CDCL requires the mixing of small oxide beads with fine powdered coal, carrying oxygen for use in initiating a chemical reaction. The resulting mixture is then heated so that coal binds with oxygen from the iron oxide to produce carbon dioxide. While the carbon dioxide rises and collects atop the reaction chamber, the subsequent generation of heat creates water vapour for use in powering steam turbines.
The otherwise-contained carbon dioxide is separated and recycled, whereas the iron beads are exposed to the air inside the reactor, resulting in re-oxidisation: this reaction allows the beads to be regenerated indefinitely for use in later processes or for storage. Current research practices demonstrate that each unit produces approximately 25 thermal kilowatts for use in generating electricity.
The associated researchers plan to develop the technology further with the construction of a pilot plant, located at the US Department of Energy‘s National Carbon Capture Centre and scheduled to begin operations in late 2013. Aiming to produce approximately 250 thermal kilowatts using syngas (synthesis gas), the tests are considered of vital importance in the technology’s commercial development.
The building of this plant further demonstrates committed government support for new, environmentally beneficial technologies. Fan has since attested to the State of Ohio being “very supportive of our research efforts” and tells of “brilliant invention and cutting-edge research,” and being “successful and progressive” in alignment with government funding.
Coal used in the generation of electricity is currently the US’ second-biggest contributor to carbon dioxide emissions and has come under increasing scrutiny amid growing public concern over global warming. The coal industry has responded by repeatedly emphasising its commitment to clean coal initiatives.
Carbon dioxide is a renewable material and might be used in future electricity generation
Over the past 30 years, more than $50bn has been deployed in the US in the development and implementation of clean coal technologies, with almost $500m devoted to carbon capture and storage research and development.
Increased US capacity for generating coal-based electricity could go some way in reducing the price of oil across global markets. Furthermore, Iraq looks set to better realise its potential as a leading oil producer, and increase its annual output by 600,000 barrels per day for the foreseeable future.
Citigroup’s Edward Morse said in a statement: “Starting this year, North American output… should start to have tangible impacts both on global prices and trading patterns, and will eventually turn the global geopolitics of energy on its head.” The shift would significantly limit the revenues of the producing OPEC nations, as well as Russia and West Africa.
How clean is ‘clean’?
Though clean coal solutions are beginning to gain some presence in the developed world, there are many who argue the legitimacy of terming these projects ‘clean’. The world’s first ‘clean coal’ power plant – built in Spremberg, Germany in 2008 – though fundamentally negating the release of carbon dioxide into the atmosphere on a short-term basis, does not provide a long-term prevention method in stopping carbon dioxide being expelled.
Having furthered developments in both clean coal technology, and in the isolation and short-term containment of carbon dioxide, the question is how it is to be recycled or contained in the long-term. Current techniques include the injecting of carbon dioxide into depleted natural gas fields or other suitable geological formations. Termed Carbon Capture and Sequestration (CCS), it is an attractive and relatively simple answer for the near-term, although it cannot be considered a permanent solution.
CCS currently sits high on the green agenda for many governments, remaining a viable option for climate change amelioration. That said, many scientists and technicians consider the burying of carbon dioxide a crucial mismanagement of a potentially viable energy source. Carbon dioxide is a renewable material – unlike those from which it’s expelled – and some chemists have questioned the methodology of burying something that might be used in future electricity generation.
With recent discoveries in the field of CCS support, demand for carbon dioxide-generated means of producing electricity has been steadily rising among scientists and engineers. The theories of how carbon dioxide could generate electricity are split into two broad schools of thought: one is the converting of CO2 into simple oxygenated compounds such as methanol; the other is the utilisation of organic matter in imitating photosynthesis. Although both branches of thought offer a sound scientific means for generating electricity, neither can be considered a commercially viable option at present.
Today we have a global economy in which highly incentivised focus is both hungry and unflinching in its efforts to improve environmental conditions. Whereas initiatives led by those such as Professor Fan are clearly making headway in the advancement of clean coal technology, there are still important related aspects for which development necessitates a vast amount of investment.
Approximately a quarter of the world’s electricity generation is provided by coal-related methods, and the process is a major contributor to proliferating environmental pollution. In this sense, it’s clear that any further attempts to better restrict harmful pollutants would be of paramount importance worldwide.