The production of electricity is a major focus of energy use, with the United States generating about 4 billion kilowatthours of electricity in 2012, according to the U.S. Energy Information Administration (EIA, 2013). Coal remains the most common source of energy for this process, while renewable energy sources, such as solar, are the type of energy source that is showing the highest growth rate (EIA, 2013). As the consumer demand for electricity keeps increasing, it makes sense to compare the various means of producing it to determine the advantages and disadvantages of using the different forms of energy available. One of the key factors in this analysis is cost, but other externalities, such as convenience, efficiency, and environmental impact should be accounted for in addition to the direct costs involved. Accordingly, the present paper will provide a brief overview of each of these areas and conclude with a summation of the advantages and disadvantages of using solar and coal as a source of energy.
As an extremely active area for energy research, there is much information available about the costs of using solar energy. In particular, the Solar Foundation has published an article examining the costs and benefits of going solar for the consumer (2012). In order to provide a general overview of the issues related to solar energy and its use, commentary is also available on the environmental impact of solar energy (Union of Concerned Scientists, 2013), measurements of the overall efficiency of solar power (EIA, 2013b), and measurements of the overall cost of solar power (EIA, 2013a). All of these recent publications help provide insights into the advantages and disadvantages of solar as an energy source.
There is also an immense amount of literature available discussing coal and its use, at least in part because it has been used as a primary source of energy for so long. Specifically, one very useful study is recent work by Epstein et al. that examines the full cost accounting for the entire life cycle of coal provides insight into the externalities involved in using coal as an energy source (2011). Additional commentary is available on the cost of coal as to safety (Iacob, 2010), the issues surrounding importing coal (Deyette and Freese, 2010), and statistics about coal and its use to produce electricity (EIA, 2013a; b). This collection of recent studies provides a solid overview of the issues involved in order to support the comparison between coal and solar power made within this paper.
Solar energy comprised approximately 0.11% of the energy used to produce electricity in the United States in 2012 (EIA, 2013). Although this number is admittedly a very small percentage of the total energy used, there is significant interest and significant investment, from both governmental and private funds, to increase this contribution. Specifically, in 2012, global private investment in solar power was $142.5 billion dollars resulting in the return of $93 billion, that is, no profit (Isola, 2013). Obviously, there is much progress to be made in order for the solar energy industry to become a profitable business. However, as will be discussed in detail below, there are distinct advantages to the use of clean energy sources, such as solar energy, in the production of electricity. Additionally, it is difficult to separate the problems with the current solar business model of having the consumer bear the investment costs from problems with the energy source as a whole (Solar Foundation, 2012). In any case, solar energy scientists are working diligently to overcome the current issues with the technology and business modes involved in an effort to make solar energy not only something that makes environmental sense, but one that makes business sense as well.
In contrast, the coal industry has long been a source of both energy and profit. Coal comprises approximately 37% of the energy source for the electricity produced in the United States in 2012. It was the top source that year, although gains were made in its market share by natural gas, the next highest used source at 30% (EIA, 2013). The coal industry has been highly profitable in recent years. For example, the three top producers of coal, Peabody Energy Corporation, CONSOL Energy, Inc., and Alliance Resource Partners, L.P., showed profits of $3,396 million $2,229 million and $1,207 million the past five years, respectively, and these are just the top three of many companies involved in the industry (Taxpayers for Common Sense, 2012). Despite these impressive numbers, the discussion below will highlight some of the issues with the use of coal, particularly in the terms of externalities, or costs that are external to the coal industry but still imparted on society with its use. Fully informed decisions about the advantage and disadvantages of the use of coal as an energy source can only be made by examining the full impact. Nevertheless, it remains that the coal industry is a significant source of revenue in the global and U.S. economy.
There are many ways to measure the cost of producing electricity so the first step in the analysis is to pick a particular value to compare. For the purposes of this paper, a useful measurement is “total system levelized cost.” Total system levelized cost is the “present per kilowatthour cost of building and operating a generating plant over an assumed financial life and duty cycle, converted to equal annual payments and expressed in terms of real dollars to remove the impact of inflation” (EIA, 2012). It is important to understand that this number does not reflect state or federal tax credits which may have a significant impact on the actual cost. However, the total system levelized cost is useful as a basis for comparative cost between energy industries. For two industries that have a lot of governmental subsidies, as both solar power and coal do, total system levelized cost is a reasonable choice for comparison.
The total system levelized cost reported by the EIA breaks down solar energy into two types, solar photovoltaic (PV) and solar thermal (EIA, 2013a). Solar photovoltaic is the best known kind of solar energy and it involves using cells that capture the sun’s energy and turns it into electricity. Solar thermal energy involves directly using the sun to alter temperature to avoid the use of other power sources to cause this energy change (EIA, 2013a). The total levelized cost for solar PV energy is $144.30 per kilowatthour. More expensive and certainly less developed is solar thermal energy, which has a total levelized cost of $261.50 per kilowatthour.
For coal, the total levelized cost is broken down into three different types: conventional coal, advanced coal, and advanced coal with carbon capture and sequestration (CCS) (EIA, 2013a). Advanced coal is conventional coal that has been treated to reduce sulfur and ash while advanced coal with CCS is the treated coal used in combination with other technologies that capture the produced carbon rather than letting it escape as carbon dioxide waste. These advanced technologies necessarily cost more money. The total levelized cost for conventional coal is $100.10 per kilowatthour, while the use of advanced coal raises the price to $123.00, and the addition of CCS technology raises it to $135.50.
The convenience of using solar energy at any particular location is dependent on how prevalent sun is in that particular location of the Earth, immediate landscape, time of day, season, and weather (U.S. Department of Energy, 2013). Sunlight can also be diffused by pollutants, forest fires, volcanos, and other naturally occurring events. Thus, it is not surprising that with all these variables the amount of sunlight in any one place at any one time is highly variable. On the other hand, sunlight is always present at some level during the daylight hours and like all renewable resources, there is no expectation of this diminishing in the near future, unlike other sources of energy that have dates where the resource will be depleted. An additional convenience is that by using available technology, sunlight can be captured and converted to energy or heat in relatively static manner. Thus on the whole, solar energy does have many aspects to it that make it a convenient source of energy.
Coal as an energy source is significantly more inconvenient than solar. Coal has been formed through compression under the ground of plant material over very long periods of time. Thus, in order to get to the coal, it has to be mined, a process that has significant safety issues, even today (Iacob, 2010). Furthermore, there are many surrounding processes involved in obtaining the coal that results in additional external costs. One of these externalities is the need to transport the coal long distances in order to get it to where it is used (Epstein et al., 2011). This inconvenience is further magnified by the amount of coal currently being imported into the U.S., an effort related to obtaining the least expensive coal possible (Deyette and Freese, 2010). All of these considerations contribute to a conclusion that coal is a relatively inconvenient source of energy.
As with costs, there are many ways to measure the efficiency of energy production. One way to compare is a measurement called capacity. Capacity is the amount a power system could produce if going at 100% output versus what it actually achieves. Capacity is a useful comparator as it looks at not only the ability to get energy from the particular source, but the efficiency of the technology used to extract the energy from the source. Using this measurement, the capacity of a coal-run power station is 63.8%, while the percent capacity of a solar PV is about 13-33% (EIA, 2013b). Thus, it is clear that using present technology coal is a more efficient means of producing electricity than solar energy, although this could change over time with advances in solar cell technology. Specifically, increased efficiency in solar cell function would be expected to positively affect the capacity of solar energy power production.
The final point of comparison is environmental impact. Comparatively, the use of solar power has less environmental impact than almost all means of producing electricity. That is not to say that solar power has no environmental impact at all. Land use and habitat loss, water use, and the use of hazardous materials in the cell production are all negative environmental impacts of the solar energy industry (Union of Concerned Scientists, 2013). In contrast, the negative environmental impacts of burning coal are extreme, to the extent that the advanced and advanced with CCS technologies have been developed despite their higher costs. Some of the well-publicized environmental impacts of burning coal are production of air pollution in the form of greenhouse and toxin gases (Epstein et al, 2011). However, it should be noted that new technologies measurably reduce these impact but do not take them to zero (Giglio, n.d.). Other environmental impacts of coal occur during the mining process such as the potential for spontaneous combustion and water table pollution (Younger, 2004). Further environmental impacts are produced during transportation of coal. All of these factors make the overall scope of the environmental impact of coal use very high.
When examined from the points of costs, convenience, efficiency, and environmental impacts, the production of electricity using solar energy and coal have some significant differences. In the present situation, coal remains cheaper than solar energy even if more expensive special technologies such as advanced coal and CCS are utilized. However, solar energy is much more convenient as it does not require the extensive mining and transportation processes or the post-capture treatments that the more expensive advanced coal requires. It is also a renewable resource and thus will not run out, although the supply of coal globally is adequate through for at least another 112 years given the current consumption rate (World Coal Association, 2011). At current technologies levels, coal is a more efficient means of obtaining energy, although as solar panels become more efficient this could change. The biggest difference between coal and solar power are the environmental impacts. Even when using clean coal technologies, solar energy has much less of negative effect on the environment and the negative effects are not as widespread. It is within the environmental impact comparison where solar energy has its best advantages over coal. However, until the cost of coal and solar energy become more similar, the demand for and profits realized from coal will remain higher than those for solar energy.
References
Deyette, J. and Freese, B. 2010. Burning coal, burning cash. Union of Concerned Scientists. [online]. Available at < www.ucsuse.org/assets/documents/clean_energy/Buring-Coal-Burning-Cash_full-report.pdf > [Assessed on July 10, 2013].
Epstein, P.R. et al. 2011. Full cost accounting for the life cycle of coal. Annuals of the New York Academy of Sciences. 1219: 73-96. Available at: <http://solar.gwu.edu/index_files/Resources_files/epstein_full%20cost%20of%20coal.pdf> [Accessed on July 10, 2013].
Giglio, R. n.d. New technologies reduce environmental impacts of coal-fired plants. EngineerLive. [online]. Available at <www.engineerlive.com/coontent/22603> [Accessed on July 10, 2013].
Iacob, Madalina. 2010. The cost of coal. Forbes. [online]. Available at <www.forbes.com/2010/04/06/coal-mine-explosion-equities-markets-massye.html> [Accessed on July 10, 2013].
Isola, J. 2013. New investment in clean energy fell 11% in 2012. Bloomberg New Energy Finance. [online] Available at <bnef.com/Downloads/pressreleases/260/pdffile/> [Accessed on July 10, 2013].
Proctor, C. 2013. In Colorado, could solar thermal energy be a more efficient answer? Energy Quarterly. [online] 24 May. Available at < http://www.bizjournals.com/denver/print-edition/2013/05/24/in-colorado-could-solar-thermal.html?page=all> [Accessed on July 10, 2013].
Solar Foundation. 2012. Solar Accounting: Measuring the Costs and Benefits of Going Solar. [online]. 23 August. Available at
< thesolarfoundation.org/sites/thesolartfoundation.org/files/TSF_SolarAcct_Final.pdf> [Accessed July 10, 2013].
Taxpayers for Common Sense (TFCS). (2012). Coal Industry Profits. [online] Available at < http://www.taxpayer.net/library/article/coal-industry-profits> [Accessed on July 10, 2013.]
U.S. Department of Energy. 2013. Solar energy resources.[online] 22 April. Available at <www.eere.energy.gov/basics/renewable_energy/solar_resources.html> [Accessed on July 10, 2013].
U.S. Energy Information Administration (EIA). 2013a. Levelized Cost of New Generation Resources in the Annual Energy Outlook 2013. [online] Available at <www.eia.gov/forecasts/aeo/electricity_generation.cfm> [Accessed on July 10, 2013].
U.S. Energy Information Administration (EIA). 2013b. What is U.S. electricity generation by energy source? [online] Available at < http://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3> [Accessed on July 10, 2013].
World Coal Association. 2011. Where is coal found? [online]. Available at <www.worldcoal.org/coal/where-is-coal-found/> [Accessed on July 10, 2013].
Younger, P. 2004. Environmental impacts of cal mining and associated wastes: a geochemical perspective. London Geological Society. Special publication. [online]. Available at <specpubgls.highwire.org/content/236/1/169.short> [Accessed on July 10, 2013].
