Today's guest column is a response to the Green Room article ""Take a clean look at nuclear energy"" by Rachel Slaybaugh.
Ms. Slaybaugh's article on the need to take a clean look at nuclear energy may have raised a few eyebrows, as clean and nuclear are rarely part of the same sentence. However, it is important to first define what makes clean energy and see how different energy options measure up on this ""clean"" scale. Cleanliness, and efficiency, of an energy source depends not only on how it is generated, but also on the complete chain of all processes involved in generating power with a given technology.
For example, solar power is always touted as the solution for all of the energy problems we face today, often forgetting how solar radiation is converted to electricity in the first place, namely solar cells. Solar cells are manufactured using metals like cadmium, arsenic, and other compounds of silicon. The metals used are rare and can be very toxic. Their metallurgy involves extraction processes generating toxic waste. Silicon is available in large quantities but its extraction is fraught with toxic and hazardous by-products. Ironically, a by-product of the process is carbon-dioxide from blast furnaces. Solar cells eventually need to be disposed of once they lose their capacity to generate electricity, which presents a waste disposal problem given the metals present in them.
A 2007 study performed at Brookhaven National Laboratory analyzed the emissions and waste generated in the metallurgical processes of metals required for solar cells. The metals used are primarily the products or by-products of copper and zinc mining and extraction. Two important metals for solar cells are indium and tellurium (zinc and copper mining by-products respectively). One tonne (or metric ton) of indium is produced for every 6000 tonnes of zinc, while 1000 tonnes of copper ore result in one kilogram of tellurium. Each tonne of zinc and copper require 30 and 25 gigajoules of energy to excavate. Every tonne of zinc results in 1.3 tonnes of carbon dioxide released as a process and energy requirement by-product. Also, the production of one tonne of zinc and copper leads to emissions of the atmospheric pollutant sulfur dioxide, lead and arsenic, as well as other metals like cadmium, chromium and mercury. These complicated figures indicate the need for a thorough understanding of the whole process to understand how waste is generated.
The point is not to discredit solar power, but to paint the complete picture behind what is generally considered a completely clean energy source. A more rational parameter of comparison would be how much chemical and industrial waste is generated for each megawatt of energy generated from the entire energy-production cycle.
Wind power is also considered a form of clean energy. But it is inherently intermittent, endemic and takes up too much space to shoulder the burden of an industrialized economy that requires steady reliable power.
Hydroelectricity is a promising source from both waste generation and scalability perspective. However, hydroelectricity also has substantial issues in the form of land area used, as well as the flooding of upstream areas due to dams and silting at the base of dams over a period time. This reduces dam efficiency and is a grave ecological hazard.
One advantage of nuclear power has always been the low tonnage of waste generated per megawatt of electricity and the energy-intensive nature of nuclear fuel, where one kg of uranium-235 has the capacity to produce about 70000 gigajoules of energy before transmission.
Used nuclear fuel, a major environmental issue, can be dealt with efficiently by reprocessing and separating it into individual constituents. France and Japan are two heavily industrialized countries that rely on nuclear power for a large portion of their electricity (79 percent and 35 percent respectively) and actively reprocess. Reprocessing allows us to take back viable fuel present in low concentrations and separates all the fission products and by-products into their individual constituents, many of which have industrial uses. Reprocessing is effectively the recycling of used nuclear fuel. The residue left is what is called high level waste. A point to be noted is that an intensely radioactive material has a shorter life and one of lower radiation intensity a longer one. For the high-level waste, technology currently exists to store this waste safely until it is rendered inactive.
Although nuclear power has a low margin of error, safety is still a high priority. All nuclear engineering programs in the U.S. have a research field devoted only to safety, something that is rare in chemical or mining industries. Statistically, the nuclear industry has one of the best safety records when compared with any other sector.
The nuclear reactors today are inherently designed to be safe and, even in theory, they cannot, given the fuel loading and geometry, ever go out of control and pose a public risk. New reactors take even greater advantage than existing reactors of a physical phenomenon called temperature feedback, and other fail-safe methods put in place that assure safe operation.
Today we need a power source that is relatively clean and can be counted on to supply power to 6.8 billion people for the coming 200-300 years, until a more viable form of energy, like nuclear fusion is harnessed.
Everything we use today requires energy to produce, whether it is toothpaste, soap or computers. Even the process of recycling has energy needs and generates waste, like when the pulp of paper mixed with acid dissolves off bottles to separate glass. To become truly eco-friendly we need a change of lifestyle that is difficult in a short span of time.
This article is not about defending one power source over another, but analyzing each without being under the impression of false notions. Contrary to popular perception, an economy completely based on solar power can place extreme strain on mining while effectively still being a source of energy dependent on non-renewables.
In summary, the points raised against nuclear power are equally pertinent for all sources of energy, even those considered ""renewable."" Based on present day requirements of reliability, scalability, and emissions control, and available technology, nuclear power presents one of the best options for us, and it should be viewed positively.
Aditya Pidaparthy is a graduate student studying nuclear engineering. You can send responses to opinion@dailycardinal.com.
