By Ye Han
REDUCING CO2 emissions is a key task of modern society to attenuate climate change and its environmental effects. Coal-fired electricity generation plants emit billions of tonnes of CO2 each year and are accountable for 30% of global CO2 emissions (according to 2018 statistics). Each year burning coal produces over 14 billion tonnes of carbon dioxide (CO2 ), which is released into the atmosphere, most of this being from power generation. Coal is the World’s most abundant and widely distributed fossil fuel source which remains the single biggest contributor to climate change. Thermal plants like coal-fired plants emit harmful substances to the environment. These include mercury, sulfur dioxide, carbon monoxide, mercury, selenium, and arsenic. These harmful substances not only cause acid rain but also are very harmful to humans as well. Therefore carbon dioxide from burning coal (a fossil fuel) is the main focus of attention today since it is implicated in global warming. (Chemically, coal is mostly carbon, which, when burned, reacts with oxygen in the air to produce carbon dioxide, a heat-trapping gas. When released into the atmosphere, carbon dioxide works like a blanket, warming the earth above normal limits.). Air pollution from coalfired power plants is linked with asthma, cancer, heart and lung ailments, neurological problems, acid rain, global warming, and other severe environmental and public health impacts. However, as much of the world lacks access to modern, clean energy, coal is still essential to alleviating worldwide energy poverty.
The 76th session of the United Nations General Assembly (UNGA 76)
The 76th session of the United Nations General Assembly (UNGA 76), where all 193 Member States are represented, was opened in New York on 14 September 2021. UNGA High-Level Week took place on 20-24 September. The United Nations Secretariat has adopted a new 10- year Climate Action Plan aimed at transforming its operations to achieve a 45 per cent reduction in greenhouse (including carbon dioxide) gas emissions and sourcing 80 per cent of electricity from renewable energy by 2030.
The world’s two largest economies, US and China, committed to more ambitious climate action during the high-level week of the General Assembly: United States’ President Jose Biden announced that his country would significantly increase its international climate finance to approximately $11.4 billion a year. President Xi Jinping of China said that he would end all financing of coalfired power plants abroad, and redirect support to green and low carbon energy generation.
Air pollution from coal-fired power plants is linked to global warming and other damaging environmental and public health consequences. UN Secretary-General António Guterres warned that obtaining energy from coal is a particular challenge. He said that “If all planned coal power plants become operational, we will not only be clearly above 1.5 degrees - we will be well above 2 degrees. The Paris targets would go up in smoke”.
(The Paris Agreement is a legally binding international treaty on climate change. It was adopted by 196 Parties at COP 21 in Paris, on 12 December 2015 and entered into force on 4 November 2016. Its goal is to limit global warming to well below 2, preferably to 1.5 degrees Celsius / 2.7 degrees Fahrenheit above pre-industrial levels).
G20 – 2021 Summit
On 30 and 31 October 2021, G20 leaders met for a two-day summit hosted by the Italian G20 presidency in Rome. UN experts say that even if current national plans are fully implemented, the world is headed for global warming of 2.70 C, with catastrophic consequences. The final G20 statement includes a pledge to halt financing of overseas coalfired power generation by the end of this year, but set no date for phasing out coal power, promising only to do so “as soon as possible”.
UN Climate Change Conference, the COP 26 climate summit, was hosted by the UK in partnership with Italy. It took place from 31 October to 12 November 2021 in the Scottish Event Campus (SEC) in Glasgow, UK (COP standing for Conference of the Parties. This is the 26th time countries have gathered under the convention.). COP26 is important because it is the first major test of the 2015 Paris Agreement. Each UN Climate Conference (COP) is preceded by a preparatory meeting held about a month before, called Pre-COP.
The outcome of COP26, Glasgow climate summit is the first one focused on coal and not the entire range of fossil fuels. Its pledge to end coal power weakened in the final compromise. But it had closed with members failing to agree on a call to “phase-out” (to discontinue the use of in phases) coal use, after a last-minute intervention by India to change the language, mentioning the terminology to “phase down” (to reduce the size or amount of by phases) of coal.
More than 40 countries pledged to phase out coal, the dirtiest fossil fuel despite the US and China promoting the ‘coal phase down’ concept. The United States, which still generates about one-fifth of its electricity from coal, also did not sign the pledge. And did not agree to stop coal development at home but promised to halt overseas funding of oil, gas and coal. But several of the biggest coal consumers were notably absent from the accord, including China and India, which together burn roughly two-thirds of the world’s coal, as well as Australia, the world’s 11th-biggest user of coal and a major exporter.
Secretary-General Antonio Guterres said the final texts were compromised and reflected the interests, the conditions, the contradictions and the state of political will in the world today.
Although progress has been made in reducing its use, it still produced about 37 per cent of the world’s electricity in 2019. Countries around the world reached an agreement to reduce coal-fired power generation in phases at the “Glasgow Climate Pact”. The centrepiece of the pact includes “reduction in phases of coal-fired power generation plants” without carbon reduction facilities and ‘acceleration of efforts to phase out subsidies for inefficient fossil fuel.
A coal-fired power station or coal power plant is a type of fossil fuel power station which burns coal to generate electricity. Coalfired plants produce electricity by burning coal which has been pulverized into a fine powder is blown into a furnace, called a boiler, and burned. The heat produced converts water, which runs through a series of pipes in the boiler to produce steam under tremendous pressure. The water is heated to a very high temperature (about 600 °C) and produce high-pressure steam (above 22 MPa/3190.83PSI). (1Megapascal = 145.038 pound per square inch). The high-pressure steam flows into a turbine and turns the blades of a turbine, which is connected by a shaft to a generator and spin up to 3,600 revolutions per minute to produce alternating current (AC) electricity at 20 kV or so. It is fed through a local transmission power line via a transformer. The steam is then cooled condensed back into the water. The condensed water is then recirculated back through the coal-fired boiler to again turn to steam and power the turbines.
In the diagram, you can see how the main use of water is to cool the condenser units, which receives the condensed steam that was used to turn the turbines. The hot, condensed steam water is run through pipes that are cooled by the cooler water withdrawn from the river or reservoir. The condensed water is thus cooled down and then recirculated back through the coalfired boiler to again turn to steam and power the turbines. This is the closed-cycle loop part of the system and it reuses the water continuously.
In the other part of the water-use cycle of the plant, the open-loop cycle, massive amounts of water are taken from a river and reservoir and are pumped to the condensers. This cooler water surrounds the pipes containing the hot condensed steam and thus is heated up a lot. The hot water is pumped from the condenser units into cooling towers (about 530-foot tall), so it can lose its heat. Each cooling tower circulates about 268,000 gallons of water per minute. Most of this water is reused after it cools, but about 8,000 gallons per minute are lost to evaporation. Thus you see the steam escaping from the tops of the cooling towers.
Coal-fired power plant development started with the introduction of the first dynamo built for power generation in 1866 by Werner von Siemens. In 1882, Thomas Edison built the first central power station in New York. The coal is combined in the air and ignited in the boiler. The carbon is oxidized to CO and CO2 . Nitrogen and sulfur contaminants are oxidized to their highest oxides. Mercury is volatilized. Other minerals are left in the ash. A coalfired power plant emits roughly twice the amount of carbon dioxide for the energy produced as a natural gas-fired power plant. Burning coal releases 2,249 lbs of carbon dioxide, 13 lbs of SO2 and 6 lbs of NOx per MWh.
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