Conventional Energy Plants: Problem and Solution
The Problem
For decades, the conventional way to deliver energy
from the point of production to consumers was via centralized power plants.
These plants emit immense amounts of greenhouse gases and other pollutants,
including particulate matter, sulphur dioxide and nitrogen oxides. Current
estimates for 2008 energy related CO2 emissions are 5,735 MMT, or 81
percent of the total emissions, are related to energy production. Greenhouse
gas emissions were estimated at 7,052 MMT for all gases in 2008 (EIA 2008).
These include energy related CO2, and other high global warming
potential (GWP) gases including nitrous oxide (NOx), and methane (CH4)
and CFCs. Energy related CO2 has been emitted more than any other
gas, and accounted for 81 percent of all emissions in 2008 (EIA 2008).
Based on three major fuels, petroleum, coal, and natural gas, petroleum is
shown to have the greatest emissions, followed by coal, and natural gas. When
emissions were broken down by sector, electric power shows the greatest impact.
Residential, commercial and industrial has the smallest impact, but it can be
argued that this sector should be included in the electric power sector since
buildings are consumers of electricity as well. In addition to greenhouse
gases, there is also waste heat, contaminated water, and solid materials such
as ash, scrubber residue, and particulate matter polluting the land and
waterways.
The conventional energy system creates many other
problems, such as groundwater and soil pollution from the chemicals involved in
cleaning and cooling parts. These systems are extremely inefficient, allowing
for price volatility and reliance on an over 100 year old transmission grid in
dire need of updating (Asmus 2001). To produce electricity, fossil fuel power
plants must withdraw water from sources such as rivers and lakes in order to
create steam to run turbines that create electricity. The boilers and other
parts must also be periodically cleaned and purged. During these processes,
used water is discharged and is contaminated with many toxic chemicals and
heavy metals (Baum, Chaisson, Miller, et al. 2003). Each year, coal fired power
plants produce over 130 million tons of CCW which consists of waste from
processes such as scrubber cleaning and other processes necessary to keep the
plants operating properly. Like purged water, component cooling water (CCW)
released into the environment is filled with toxic chemicals and heavy metals,
and often a single power plant requires several acres to dispose of the waste
(NRDC 2007). The conventional energy system also costs Americans billions of
dollars annually in health costs. A 2009 study by the National Academy of
Sciences revealed that each year fossil fuels cost Americans $120 billion in
human health damage. $62 million of this is caused solely by coal power plants
(AWEA 2010)
The Solution
Conventional power plants are producing only 33% electricity and the remaining 67% is waste. This type of power plant has been and is till being in increasing numbers around the world.
Burning gas in a gas turbine (GT) produces not only power - which can be converted to electricity by a coupled generator - but also fairly hot exhaust gases. Routing these gases through a water-cooled heat exchanger produces steam, which can be turned into electricity with a coupled steam turbine and generator, producing high power outputs at high efficiencies (up to 68%) and with low emissions.