Carbon dioxide capture from power plants: Sally Benson speaks to Near Zero
The tradeoff between the immediate burning of a lump of coal vs the long term global warming it generates: Ken Caldeira
Coal constitutes a large portion of primary energy supply in the world. In 2018, coal accounted for 27.2% of world primary energy consumption, its lowest in fifteen years [BP, 2019]. After two subsequent years of decline in coal consumption in 2015 and 2016, 2017 saw a 1% increase in coal consumption to a net 7585 metric tons of consumption. The increase in demand was due to significant increase in consumption in India, Korea and China [IEA, 2018]. In 2018, coal demand (1.4%) increased for the second consecutive year. OECD demand fell to its lowest consumption growth levels since 1975 [BP, 2019].
Coal currently supplies a third of global energy use and accounted for 38% of electricity generation in 2017, an increase of 3% from 2016. If the UN Sustainable Development Goals are to be satisfied, an annual decrease of 5.6% in coal-based electricity generation is required [IEA, 2018].
More than 20 countries launch global alliance to phase out coal for climate mitigation purpose in Conference of Parties (COP) 23. By April 9, 2018, the number of alliance members has grown to over 60 [UNFCCC, 2017; Government of Canada, 2018].
In the United States, natural gas surpassed coal as the number one producer of electric power in 2016, and in April and May of 2019 renewable energy supplied more power than coal for the first time [Utility Dive, 2020].
Imminent Breakthroughs
The most promising 'clean coal' technology involves using the coal to make hydrogen from water, then burying the resultant carbon dioxide by-product and burning the hydrogen [WNA, 2017].
As part of the Conference of Parties (COP) 24 held in 2018, action to shift away from coal-based electricity generation garnered further attention. The Powering Past Coal Alliance (PPCA) as of December 2018 has 30 national governments, 22 sub-national governments and 28 businesses as members. The PPCA has targets to completely abandon coal-based electricity generation by 2030 for EU and OECD countries. Other member-countries have a target year of 2050 [PPCA, 2018].
Co-gasification of coal and biomass is emerging as a greener alternative. Coal and biomass have been gasified independently for multiple decades now. Co-gasification helps transcend the low thermodynamic utilization rate of coal and also helps lower carbon emissions. This is identified to be a very useful solution for developing countries like India, that is expected to be increasingly coal dependent in the next decade. [Kamble et al., 2019].
Clean coal technologies are getting attentions, and the Carbon Capture & Sequestration (CCS) is encouraged to facilitate to achieve zero-emission goals [WCA, 2017a].
The most promising clean coal technology is using coal to make hydrogen from water, then burying the resultant CO2 by-product and burning the hydrogen [WNA, 2017].
Obstacles to TW-Scale Integration
Hard and Soft Coal
- The average coal-fired power efficiency around the world is 33%, which is much lower than the state-of-art rate 45% [WCA, 2017b]. To achieve the sustainable development of energy, public opposition to coal utilization has been gaining ground in recent years, and the IEA recommended to phase out the use of least-efficient coal-fired power plants [IEA, 2015]. However, coal utilization is globally widespread for the energy availability, accessibility and low cost. [WCA, 2017].
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Expansion of coal-based generation is constrained by costs. The US has achieved ‘coal cost crossover’, which implies that existing coal is increasingly more expensive that clean-tech alternatives. Approximately 74 percent of US coal can be replaced by clean energy alternatives, specifically wind and solar, generating savings in the process [Energy Innovation, 2019].
Peat
- Over 90% of peatlands are located in the temperate and cold belt in the Northern Hemisphere, and is not optimal for peat resource extraction [IPS, 2017a]. There is significant public opposition to the extraction of peat for energy use given its carbon content and ecological footprint [IPS 2017b].
Enabling Technologies
There are two types of coal mining, surface (opencast) and underground (deep), and both use specific technology:
- Large, opencast mining is economic when coal is near the surface, and technology can recover 90% or more of the coal using draglines, power shovels, large trucks, bucket wheel excavators, and conveyors [WCA, 2017].
- Underground mining occurs via room-and-pillar or longwall mining [WCA, 2017].
Political Considerations
Hard and Soft Coal
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With the ratification of the Paris Agreement, the world is confirming the need for an inter-governmental commitment to CCS in a variety of applications, including coal and natural gas-fired power generation [CIAB, IEA, 2016]. In the U.S., Control technologies have been implemented at coal-fired units to keep consistent with the Clean Air Act [EPA, 2016a].
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Coal consumption is shifting to the East, with decline in Europe and North America and increase in Asia, indicating that a geographical split may emerge in the world’s reliance on coal [IEA, 2016].
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Most coal is consumed where it is extracted, with only 15% of coal traded globally [WCA, 2014]. Asia is the predominant destination for coal exports, mainly China and India, followed by Europe and the U.S. The projected share of total world international coal imports ranging from a low of 75% in 2020 to a high of 78% in 2040 [EIA, 2016].
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Direct and indirect subsidies play a major role in the success of fossil fuels, including coal [Kenny, 2012].
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Seventy-six percent of the global recoverable reserves are located in five regions: the US (26%), Russia (18%), China (13%), non-OECD Europe and Eurasia (10%), and Australia/New Zealand (9%) [EIA, 2016].
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Coal-based generation is kept alive by several local and state governments, despite unfavorable economics and threat of future regulatory changes, owing to the continued dependence of the communities on coal. In the US, Wyoming passed a bill in 2019 to delay the retirement of coal plants by mandating utilities to make an effort to sell economically under-achieving coal plants and continue buying power from the potential buyer, ahead of recovering the cost of replacement plants [Utility Dive, 2019]. Poland predicts that coal would constitute 50 percent of its generation even as late as mid-century. Several communities in Poland depend on coal and it is a part of Poland’s long-surviving culture [The Washington Post, 2018].
Peat
- Many countries have moved away from peat as an energy source due to its inefficiency, and significant contributions to climate change [IPS, 2014].
Social Considerations
Hard and Soft Coal
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Developed and developing societies alike currently rely on coal; coal meets 23% of primary energy needs and generates 39% of global electricity. About 70% of steel production depends on coal as a feedstock [WNA, 2014].
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The burning of coal can be a public health hazard. Coal mining and transportation release carcinogenic matters, which create significant hazards, both to workers and the public. In addition, the air pollution from coal burning is what most threatens health, causing heart and respiratory diseases [Smith, 2013].
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Over the last fifty years, changes of several kinds have contributed to a decline of 4 million coal jobs. The primary drivers for coal job losses are identified to be increasing mine mechanization to improve operational efficiencies, advent of clean energy policies, reduced consumption due to energy efficiency measures, and other energy technologies being cheaper [World Bank, 2018].
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While the number of coal-related jobs may constitute only a small sector in the total job-market of countries, these jobs are often very local and mine-closures can have devastating impacts on specific communities [World Bank, 2018].
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Several governments have launched revitalization programs for laid-off coal workers. In the United States, the Department of Labor’s Employment and Training Administration is aiding coal-dependent states to revitalize their workforce. The POWER programs in Ohio and Kentucky are examples of worker retraining programs. The retrained workers are being equipped for employment in heavy machinery industries, IT, healthcare and agriculture to name a few [US Department of Labor].
Peat
- The harvest of peat leads to the destruction of mires in northern Europe as well as the tropics, leading to strong public resistance against peat as an energy source [IPS, 2014].
Environmental Considerations
Hard and Soft Coal
- Burning coal generates emissions including SO2, NOx, CO2, which contribute to air pollution and climate change [IEA, 2017]. Coal-fired power plants provide over 42% of global electricity supply, accounting for over 28% of global CO2 emissions [CIAB, IEA, 2010]. Coal and coal waste, which include fly ash, bottom ash, and boiler slag, are also one of the major sources of toxic chemicals and heavy metals in the atmosphere, including arsenic, lead, mercury, nickel, vanadium, beryllium, cadmium, barium, chromium, copper and radium [Nalbandian, 2012].
- In underground mining, waste materials that are piled at the surface can be disturbed by runoff, which in turn carries dissolved solids to local water sources. Acid mine drainage pollutes streams and lakes, and if it seeps into groundwater, it can contaminate aquifers [CATF, 2001].
Peat
- The harvest of peat leads to the destruction of mires in northern Europe as well as the tropics, which can have dramatic impacts on the ecosystems of the region, as well as undermining soil integrity [IPS, 2014].
- Peat releases less SO2 than other fossil fuels when combusted [IPS, 2014].
- The drainage of peat releases a substantial volume of water, which can contaminate downstream waterways [IPS, 2014].
References:
BP Statistical Review of World Energy, 2019. https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2019-full-report.pdf
Coal Industrial Advisory Abroad (CIAB), IEA. 2016.
EIA. Annual coal report. 2017. https://www.eia.gov/coal/annual/
EIA. International Energy Outlook 2016.
Energy Innovation Policy & Technology LLC, 2019. https://energyinnovation.org/publication/the-coal-cost-crossover/
EPA. 2016. https://www.epa.gov/airmarkets/clean-air-markets-emissions-tracking-highlights#Coal
Government of Canada. (2018). Coal phase-out: the Powering Past Coal Alliance. https://www.canada.ca/en/services/environment/weather/climatechange/canada-international-action/coal-phase-out.html
Utility Dive. 2020 Outlook: Coal status in the United States, 2020. https://www.utilitydive.com/news/2020-outlook-coal-faces-headwinds-from-aging-plants-adverse-market-signal/569732/
Herminé Nalbandian. Trace element emissions from coal. 2012. https://www.usea.org/sites/default/files/092012_Trace%20element%20emissions%20from%20coal_ccc203.pdf
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https://www.iea.org/reports/medium-term-coal-market-report-2016
International Peatland Society. https://peatlands.org/peat/
Kamble, Alka D., et al. "Co-gasification of coal and biomass an emerging clean energy technology: status and prospects of development in Indian context." International Journal of Mining Science and Technology 29.2 (2019): 171-186.
Powering Past Coal Alliance, 2018. https://poweringpastcoal.org/about/Powering-Past-Coal-Alliance-Mission
Smith, K. R. (2013). Smoked out: the health hazards of burning coal. The Lancet, 381(9882), 1979.
Ümit Şahin. 2018. Hope for coal phase-out after COP23. Green European Journal. Retrieved from: https://www.greeneuropeanjournal.eu/hope-for-coal-phase-out-after-cop23/
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United States Department of Labor. https://www.dol.gov/owcp/dcmwc/powergrants.htm
Utility Dive. Wyoming Coal Plant Bill, 2019. https://www.utilitydive.com/news/wyoming-passes-coal-support-bill-in-spate-of-western-action-to-save-ailing/549753/
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WCA, 2017a. https://www.worldcoal.org/net-zero-emissions-new-climate-target-and-new-chance-coal
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World Nuclear Association (WNA). 2017. http://www.world-nuclear.org/information-library/energy-and-the-environment/clean-coal-technologies.aspx