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SCIENCE LITERACY ARTICLE 6 – for November 18, 2011

THE CONTROVERSIES BEHIND THE CONSTRUCTION OF ZC 100 MW COAL-FIRED POWER PLANT

“A power company is expected to start construction of a 100-megawatt coal-fired power plant by June, next year at barangay Talisayan, over 20 kilometers west of the city proper, according to the Zamboanga City Electric Cooperative or

ZAMCELCO “

ZAMCELCO President Efren Perez said that the memorandum of agreement for the P12-billion project is expected to besigned between the cooperative and project proponent Conal Holdings Corporation by December.

Perez said that 97 out the 98 barangays in this city already manifested the support for the construction of a plant by theConan Holdings Corp. The only barangay opposing the project is Talisayan where the project will be located.

The power plant will supply electricity to the city and thus ensure that there will be “zero” blackout as it starts producingelectricity using coal. Zamboanguenos appreciates the big help to Zamboanga’s electricity supply, and that the ‘blackoutcrisis’ will be solved.

But before jumping to conclusions, everyone should know what a coal-fired power plant is. More than half of the

electricity generated in the world is by using coal as the primary fuel. The function of the coal fired thermal power plant isto convert the energy available in the coal to Electricity. Coal power plants work by using several steps to convert storedenergy in coal to usable electricity that we find in our homes that powers our lights, computers, and sometimes, back intoheat for our homes.

Though appearing very easy and helpful, one should always take into consideration nature’s sake.Here are some key facts about a coal-fired electricity production. As an example consider these facts for typical coal firedpower plant of capacity 500 MW.• Around 2 million tons of coal will be required each year to produce the continuous power.• Coal combustion in the boiler requires air. Around 1.6 million cubic meter of air in an hour is delivered by air fans into

the furnace.• The ash produced from this combustion is around 200,000 tons per year.• Electrostatic precipitators capture almost all of this ash without dispersing this to the atmosphere. Pollutants from

coal power plants like carbon dioxide, sulphur dioxide, and nitrogen oxide can also affect the environment. Thermalpower plants are the biggest producers of Carbon Dioxide.• The boiler for typical 500 MW units produces around 1600 tons per hour of steam at a temperature of 540 to 600

degrees Centigrade. The steam pressures is in the range of 200 bar. The boiler materials are designed to withstandthese conditions with special consideration for operational safety.

• Heat transfer from the hot combustion gases to the water in the boiler takes place due to Radiation and convection.• The Electrical generators carry very large electric currents that produce heat and are be cooled by Hydrogen and

water.• The steam leaving the turbine is condensed and the water is pumped back for reuse in the boiler. To condense all the

steam it will require around 50,000 cubic meter per hour of cooling water to be circulated from lakes, rivers or thesea. The water is returned to the source with only an increase of 3 to 4 degrees centigrade to prevent any effect to theenvironment.

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• Apart from the cooling water the power plant also requires around 400 cubic meters per day of fresh water for makingup the losses in the water steam cycle.

Though in our case, where only a 100 MW plant will be built, the effects may be lessened, but they are still there. We mustremember that not everything that helps is entirely good. Coal may be a very good source of energy for us, but just likeevery other power plant, with every bit of energy that we harness, we pollute the environment.

Sources:begins-june-2012-perez.html http://www.brighthub.com/engineering/mechanical/articles/18082.aspx