With global energy demands rising and our reserves of fossil fuels decreasing each day, many are looking towards alternative energy sources as a way out of our current predicament. As there are a myriad of alternative energy sources to choose from, a key question has become which are actually better alternatives to fossil fuel consumption? While just about every alternative I am aware of emits less pollution during energy production than the burning of fossil fuels, are they actually better? To answer this, one must look at the entire life cycle of a technology, not just how well it works once it is created and working at full capacity. A paper in a recent edition of the International Journal of Global Energy Issues delves into exactly this issue.
By using a technique known as life cycle assessment, a pair of Greek researchers look at the total environmental impact of alternative energy technologies as compared to the impact of an equivalent energy output through burning fossil fuels. A life cycle assessment takes into account more than just comparing the energy output of two working energy systems: it compares the flow of material and energy used in the construction, operation, and ultimate decommissioning of a renewable energy supply. In addition to these terms, it takes into account the impact of manufacturing the materials needed to extract energy, as well as waste generated by the process.
It was found that wind and geothermal energy are indeed green alternatives. The efficiency of these systems—over their entire life cycle—is comparable to that of fossil fuels. It was found that solar power did not fare as well. The electricity produced by photovoltaic cells is less efficient when production, running, and recycling is taken into account. However, solar energy has the benefit of economy of scale; if you produce enough solar cells and have them covering a large enough area, the total life cycle efficiency for the generated electricity tips in the favor of solar cells when compared to traditional fossil fuels. Also, the authors noted that the pollution of solar systems is far, far less then traditional fossil fuels, even though they represent a lower thermodynamic efficiency. As the authors state, "A significant advantage of the use of renewable energy systems is that they are environmentally friendly because overall they result in lower dangerous pollutant emissions, this and one other major factor, they are essentially inexhaustible."
Int. J. of Global Energy Issues, 2007. DOI: 10.1504/IJGEI.2007.014865