Coal, natural gas, and nuclear power make up the largest sources of electrical power production in the United States.  Each presents it’s own set of benefits and challenges.

In most conventional nuclear power plants, heat from radioactive decay is used to heat water, that is then used to spin turbines slaved to generators to create electricity, the steam is then cooled in a condenser (usually a large body of water such as a lake or cooling tower) and then returned back to the system to be used again.   Perhaps the most demonized of the group, nuclear energy may prove to be the most environmentally friendly to the environment in both the short and the long term.  While providing megawatts of power with virtually no green house gas emissions is a major plus, nuclear power also suffers from the dual detractors of relatively high cost of generation (11 cents/kWh) as well as the perennial issue of no long term radioactive waste disposal.

Yucca Mountain, a proposed long disposal site for nuclear waste in the US was canceled due to waste containment design flaws and poor site selection.  Without a viable plan for long term disposal as well as the recent disaster at the Fukushima Diiachi plant in Japan , wariness in public sentiment continues to hamper expansion of nuclear energy in the US.

Coal fired power plants work in a slightly different fashion wherein coal is pulverized to a fine powder and then burned in a firebox to produce rather high temperatures (up to 1000 C), this heat is used to convert water to high pressure steam that, much like in nuclear power, is used to spin turbines connected to electrical generators.  The water is once again cooled in a condenser and returned to the system.  The biggest, and most detrimental, difference is that the combustion of coal produces by-products. While most of what we see emanating from smoke stacks is water vapor, CO2 and SO2 (Sulfor Dioxide) create worrying challenges on the climate change front.  CO2 can make up to %15 of dry air volume emissions from these plants. While Carbon Capture and Storage, the sequestration of harmful emissions before they can be released into the atmosphere, provide some relief, CO2 from coal remains one of the most worst greenhouse gas pollutants.   That, however, is offset in this country by the vast reserves the United States possesses, making energy production from coal fairly cheap (4.5-5.5 cents/kWh).  As it supplies roughly %50 percent of the electricity in the US, without a drastic change in price or policy, this isn’t likely to change.

Natural Gas is rapidly becoming the best, worst case option for electrical generation in the US.  Not only does it produce a nominally less harmful emission than coal, it has also become cheaper as far as electrical generation is concerned (about 4 cents/kWh).  Natural gas produces energy in a fashion similar to coal, only it only requires a gas boiler to super heat the steam.  However, a recent study found that switching to natural gas, which many power plants are doing for obvious reasons, will not necessarily help the environment.  The study by Environmental Research Letters found that between now and 2055, the impact of a switch would only reduce greenhouse gases by %9, an amount to small to make significant changes.  But the switch would also delay the transition to and improvement of more environmentally friendly options such as solar, wind, and other carbon neutral sources.  Further, Methane while used in lesser quantities has a CO2 equivalence of 70 to 100.  This means that while significantly less harmful byproducts are a emitted, they can have an effect 100 times worse for the environment.

Fundamentally, all choices have drawbacks.  The task now before policy makers, and society at large, is determine which are the best among a host of bad options and then to purse them with gusto.  If our progeny are to have any semblance of decent standard of living, we have no other choice.

http://www.nirs.org/radwaste/yucca/whyyuccawouldfail2010.pdf

http://www.theguardian.com/environment/2012/mar/08/fall-nuclear-power-stations-fukushima

http://www.duke-energy.com/about-energy/generating-electricity/coal-fired-how.asp

http://peswiki.com/index.php/Directory:Cents_Per_Kilowatt-Hour

http://news.nationalgeographic.com/news/energy/2014/09/140924-natural-gas-impact-on-emissions/