Coal: A mixed blessing?

By Gerry T. Estrera
“Among the materials that are dug because they are useful, those known as anthrakes (coals) are made of earth, and, once set on fire, they burn like charcoal. They are found in Liguria … and in Elis as one approaches Olympia by the mountain road; and they are used by those who work in metals.” — Theophrastus, On Stones
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Damned if you, damned if you don’t.  Such is the case of using coal as source of power.  If coal is not used for power generation, it’s damned.  And if it used, it’s still damned.  The demand is seen to intensify as population continues to increase each year.
Whether Filipinos like it or not, the country’s power supply will be unstable.  This is particularly true in Davao, where the economy is booming.  In fact, from time to time, brownouts happen every now and then.
“One of these days, about 10 years from today, we will completely lose our energy,” explained Davao City Mayor Rodrigo R. Duterte on why he defended the approval on second reading the request of Therma South, Inc. to expand its generating capacity in barangay Binugao, Toril from 300 megawatts (MW) to 645 MW.
Duterte told the local media that all mans should be utilized to meet the power demand.  As there are no economically viable alternatives of energy sources right now, he singled out coal as the best possible solution.
 “Coal is the cheaper and more accessible source of power that could satisfy the (growing) demand of the city,” Duterte pointed out.  He added that oil as a source of power is too expensive.  As for the geothermal from Mount Apo, it can only give about 30% of the city’s power needs.
Environmentalists, however, are worried that the coal fired-power plant would harm the ecology and jeopardize the health of the communities where the plant is located.  “I am the mayor,” he said, “Do you think I will allow that to happen?  Am I that stupid?”
Coal (from the Old English term col, which has meant “mineral of fossilized carbon”) is a fossil fuel that supplies 28 percent of the world’s fuel.  “Coal began to form 300 million years ago when large regions of the earth were covered with tropical swamps containing dense vegetation,” wrote H. Steven Dashefsky, author of Environmental Literacy: Everything You Need to Know about Saving Our Planet.  As the fast-growing vegetation died and accumulated under the water, it formed a material called peat, which is the first step in the formation of coal.  The peat was gradually covered by sediment.
“Over time, pressure squeezed out much of the water and compressed the peat into lignite coal (also called brown coal), which contains about 40% moisture.  With heat from the earth and continued pressure, lignite was transformed into a soft type of coal balled bituminous coal, which has only about 3% moisture.  With continued heat and pressure, hard coal called anthracite was finally formed.”
The entire process took hundreds of millions of years.  “Coal is not a pure substance,” wrote Penelope ReVelle and Charles ReVelle, authors of The Environment: Issues and Choices for Society.  “In addition to carbon, it contains inorganic material that remains after coal has been burned; it’s called ash.  Sulfur also occurs in coal, sometimes as iron sulphide and sometimes combined with organic compounds.  Arsenic is also present in coal, as are radioactive elements.”
 Coal may be “the dirtiest of the fossil fuels,” but it is a magnificent source of heat energy.  “Burning 0.454 kilogram of bituminous coal releases 13,000 Btu, or 13,700 kilojoules of heat energy,” the ReVelles wrote. 
 Wikipedia shares this information as to how coal is used for electricity generation:  “(Coal) is usually pulverized and then combusted (burned) in a furnace with a boiler.  The furnace heat converts boiler water to steam, which is then used to spin turbines which turn generators and create electricity. The thermodynamic efficiency of this process has been improved over time. Simple cycle steam turbines have topped out with some of the most advanced reaching about 35% thermodynamic efficiency for the entire process. Increasing the combustion temperature can boost this efficiency even further.”
At least 40% of the world’s electricity comes from coal.  In 2012, about one-third of the United States’ electricity came from coal.  Ten percent of the world’s coal reserves (identified deposits) are located in the US, with over 50% in China.
“Coal reserves are expected to last about 220 years if existing demand continues,” Dashefsky wrote.  “The projected amount of coal resources (unidentified deposits), however, might last about 900 years with the current demand.”
Coal contains high heat content at economical costs, but many environmental problems are associated with its use.  Coal is touted to be the dirtiest fossil fuel to burn and it generates hundreds of millions of tons of waste products, including fly ash, bottom ash, and flue-gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals. 
Burning of coal releases pollutants that help contribute to acid rain.  In addition, the burning may release more carbon dioxide into the atmosphere thus causing the climate change phenomenon.  Studies have shown that coal-fired electric power generation emits around 2,000 pounds of carbon dioxide for every megawatt-hour generated.  This is almost double the approximately 1100 pounds of carbon dioxide released by a natural gas-fired electric plant per megawatt-hour generated.
According to Wikipedia, coal-fired power plants without effective fly ash capture systems are one of the largest sources of human-caused background radiation exposure.  They also emit mercury, selenium, and arsenic, which are harmful to human health and the environment.
But there’s good news.  “New technologies can burn coal more efficiently and more cleanly,” Dashefsky noted. “This includes the fluidized-bed combustion method, which will begin replacing old-style coal burners.  It converts solid coal into gas or liquid fuels called synfuels.”
Coal gasification converts solid coal into a gas synfuel called synthetic natural gas.  Coal liquefaction turns it into a liquid synfuel such as methanol.  Both types of synthetic fuels produce much less air pollution than burning solid coal. 
“Liquid fuels are more functional than solid fuels for heating homes and running automobiles and other forms of transportation,” Dashefsky pointed out.  “They can also be transported through pipelines whereas solid coal must be shipped.”
Meanwhile, Mindanao gets its power from four major sources: hydropower, coal, oil, and geothermal — in that order.  The bulk – 662 MW or 52% – comes from hydropower. Oil contributes 24% of the power supply (311 MW) while geothermal is the source of 8% (98 MW). The remaining 16% (203 MW) comes from coal.
“We are heavily dependent on hydropower which is coming only from one source, Lake Lanao,” says Manuel ‘Bobby’ Orig, first Vice President for Aboitiz Power Corp. in Mindanao. “This is the reason why during summer months or during long dry spell, when water level in Lake Lanao is very low, the power supply in Mindanao is gravely affected.”