COAL Maggie, Gus, Kylie, and Sam
Is coal efficient? Coal is economically efficient, readily available for use now, and is present in larger quantities than oil and natural gas. If coal is to remain a part of our energy future, it must be mined responsively, burned cleanly, and guaranteed to not worsen climate change and pollution. Currently, there is no existing coal technology that meets these standards.
What? Coal isn’t efficient? It’s not efficient, but it’s cheap and plentiful. The average coal plant in the United States is only 33% efficient. However, organizations like the World Coal Association is working to improve coal efficiency levels.
But they’re working on it! New techniques include the fluidised bed combustion, supercritical and ultrasupercritical technology and integrated gasification combined cycle.
Fluidised Bed Combustion FBC systems improve the environmental impact of coal-based electricity, reducing SOx and NOx emissions by 90%. In FBC systems, coal is burned in a reactor comprised of a bed through which gas is fed to keep the fuel in a turbulent state. This improves combustion, heat transfer and recovery of waste products. The higher heat exchanger efficiencies and better mixing of FBC systems allows them to operate at lower temperatures than conventional pulverised coal combustion systems. By elevating pressures within a bed, a high-pressure gas stream can be used to drive a gas turbine, generating electricity. http://www.youtube.com/watch?v=cmm5R_km4Kk
Supercritical and Ultrasupercritical Technology New pulverised coal combustion systems operate at increasingly higher temperatures and pressures and therefore achieve higher efficiencies than conventional PCC systems and significant CO2 reductions. Supercritical steam cycle technology has been used for decades but is now becoming the system of choice for new commercial coal-fired plants around the world. Ultrasupercritical units operate at even higher efficiencies, ideally up to 50%. These operating systems are currently researched and used in Denmark, Germany and Japan to achieve improved efficiencies and reduce fuel costs.
Integrated Gasification Combined Cycle Also known as IGCC, this system is improving upon pulverised coal-fired power stations through the use of gasification. IGCC uses a gasifier to convert coal to syngas, which drives a combined cycle turbine to generate electricity. Waste heat from the gas turbine is recovered to create steam which drives a steam turbine, producing MORE electricity.
But pollution and stuff The disadvantages of coal include: -Greenhouse gas emissions (all of which can cause different respiratory health conditions) -Sulfur Dioxide: Leads to acid rain formation -Carbon Dioxide -Nitrogen Oxides -Mining coal is really dangerous, and miners while working under treacherous working conditions also suffer health conditions -Also, coal is a nonrenewable resource.
Bibliography -www.worldcoal.org -www.sierraclub.org -http://www.eia.gov/coal/ -http://fossil-fuel.co.uk/coal/advantages-of-coal -http://sunglitz.wordpress.com/2011/02/01/advantages-and-disadvantages-of-using-coal-energy/ -http://coalenergysource.blogspot.com/2013/01/advantages-and-disadvantages-of-coal-as.html -http://www.eia.gov/tools/faqs/faq.cfm?id=107&t=3