Remembering Chernobyl and what it means for the energy challenges of the future.

On April 26 1986, a series of explosions at a nuclear power plant in Chernobyl, Ukraine led to the emission of huge amounts of radioactive contaminants over a wide geographical area. Much of Europe was contaminated with catastrophic levels of ionizing gamma radiation and nuclear fission particles including radioactive iodine, cesium and strontium.  As of 2008, the WHO estimates the deaths resulting from the long term effects of the radioactive fallout from the accident at 4,000. Other estimates range from 200,000 to 985,000. On the 25th anniversary of what has become the worst nuclear accident in history, it’s important to reflect on the role of nuclear energy and engage in a broader discussion on global energy consumption patterns.

The US Department of Energy estimates that nuclear energy currently accounts for 20% of US electricity and 70% of its “carbon free” electricity. Fossil fuels account for close to 70%  of US electricity generation with coal accounting for 46%, natural gas 23% and petroleum 1%. Coal accounts for the bulk because it is a relatively cheap source and it occurs naturally in abundant proportions in the United States.

Unfortunately, burning fossil fuels to generate electricity leads to significant environmental pollution. Combustion of coal for instance produces unfathomable amounts of green-house gases such as carbon dioxide, carbon monoxide, sulfur dioxide and heavy metals like mercury, uranium, thorium and arsenic. Plumes of thick poisonous smoke billowing from coal-fired plants produce significant amounts of fly and bottom ash that permanently stay in the earth’s atmosphere and become smog. Aside from the green-house gases and their well known effects on global warming and climate change, the ash predisposes residents in close proximity to fossil-fuel combustion plants to lung cancer. Coal mining can also affect the water table and contaminate underground water. Arsenic and mercury poisoning of underground water resources has led to many deaths in Bangladesh and neighboring countries. In addition to the green-house effects of sulfur dioxide, it also contributes significantly to acid rain.

With such a devastating environmental impact, it’s important to focus attention on carbon free sources of energy. The Obama administration has been making a strong push for clean energy with emphasis on renewable sources such as wind, solar and hydroelectric power. In December 2010, however, Energy Secretary Steven Chu said that the administration’s push for a clean energy standard could include non-renewable sources such as nuclear energy and clean coal. While nuclear energy is carbon free it comes with a separate set of costs. In the wake of the Fukushima I nuclear crisis following the March 11 tsunami in Japan, nuclear energy as a source of generating electricity has come under serious scrutiny.

Nuclear power is produced by the splitting of the nucleus of dense fissile material (such as uranium or plutonium) which generates an incredible amount of energy. This reaction is referred to as nuclear fission. Nuclear fission is exothermic (meaning heat is released) and it is that heat energy that powers a nuclear reactor to generate electricity. The problem with nuclear fission however is that the nuclear chain reaction produces particles that are different from the original element, a process called nuclear transmutation. Therefore the fission products – iodine, cesium, krypton, cadmium, strontium, xenon, lanthanides, etc tend to be highly radioactive. They have unstable nuclei and decay spontaneously by emitting ionizing radiation. They become even more dangerous when radioisotopes of iodine and cesium get absorbed in the human food chain. These ultimately become silent killers because they are absorbed into the leucocytes predisposing people with prolonged exposure to leukemia and other forms of cancer. Cesium-137 is even more dangerous this way because it has a half life of 30 years. This poses a serious problem for nuclear waste disposal and storage.

Normal waste can be easily disposed – hydrocarbons can be recycled, organic waste decays naturally because it’s biodegradable and the rest can be incinerated. The problem with nuclear waste is infinitely more complicated. Uranium 235, the uranium isotope used as a fuel rod in nuclear plants has a half-life of 700 million years. Half-life is the time it takes for an element undergoing radioactive decay to decrease by half. With a half life that long it becomes a major headache to safely dispose of spent nuclear fuel. It’s also worth noting that while spent uranium undergoes its natural decay in storage it emits particles/fission products that are also radioactive.

The largest environmental cleanup exercise in the world is currently underway at the Hanford nuclear site in Hanford, WA.  Hanford was the first full scale plutonium production reactor in the world. The plutonium bomb dropped on the city of Nagasaki during Word War II was manufactured at Hanford. The facility was decommissioned in the 1970s but disposal of the radioactive waste has been a problem since then. Much of the spent nuclear waste on the site is stored underground in double shell tanks. These tanks have corroded from rain over the decades and it is feared that liquid radioactive waste could seep into the ground and contaminate the area’s underground water and possibly the Columbia River further downstream. A major groundwater remediation project costing the government billions of dollars is currently underway there. Furthermore, the Hanford Waste Vitrification Plant (after construction is complete) will process nuclear waste into canistered glass logs for long term disposal at an underground national repository yet to be determined. The purpose of vitrification is to make radioactive waste stable (neither decay nor react with other elements) by heating the radioactive waste in a furnace with fragmented glass. The resulting glass is a new substance in which the waste is bonded into the glass matrix when it solidifies. This new glass is very stable and suited for long term underground storage for up to thousands of years. This project has been ongoing for close to a decade and it’s expected to cost the federal government up to $200 billion in 50 years.

Obviously, nuclear energy is not necessarily “better” than fossil fuels as the costs of disposing spent nuclear fuel is enormous. In addition, nuclear reprocessing technology can be used to sequester and harvest fissionable (weapons grade) plutonium from spent nuclear fuel to manufacture nuclear weapons. Over 90% of spent nuclear fuel is made up of several isotopes of uranium. Reprocessed uranium can also be re-enriched to recover Uranium-235 which is weapons grade. The by product of uranium enrichment, depleted uranium is commonly used in mortar shells of army tanks. Given it’s potential to lead to the proliferation of nuclear weapons, spent nuclear fuel (or their lack of proper disposal) poses significant challenges. Despite this grim picture, there is some hope. There are significant technologies out there that can considerably facilitate the disposal of heavy metal and nuclear waste.

Two such technologies were developed by ChemNano Materials Limited, a startup based in Akron, OH. The company owns patents to two technologies that remove heavy metals and radionuclides (including uranium and plutonium) from liquid or gas. NanoDM is the sequestering agent for heavy metals and NanoUREX for radionuclides. NanoDM can remove heavy metals such as lead, mercury, zinc, arsenic, copper, chrome, and cadmium from liquid or gaseous industrial waste in two simple steps. Waste streams from coal fired plants, ore refineries or chemical processing plants that contain such heavy metals pass through NanoDM which then captures the target metals after a few hours of contact. NanoDM sequesters the metal waste onto solid NanoDM polymer matrix. The efficiency of this technology can significantly save millions of dollars by eliminating several stages in the current treatment of the waste. This technology can significantly complement current clean coal technology to make coal more appealing as a source of energy.

NanoUREX sequesters liquid radioactive waste nuclides onto a solid nanotube matrix. By passing the liquid radioactive waste over the matrix, NanoUREX concentrates the liquid waste which makes it coalesce into solid around the nanotube matrix. This can considerably reduce the volume of radioactive waste for storage. A 2005 Congressional report states that as of the end of 2004, total inventory of discharged spent fuel from nuclear power plants across the country was 54,000 metric tons. NanoUREX can help reduce the volume of this radioactive waste considerably. The technology can also complement the vitrification plant at Hanford, WA by reducing the volume of nuclear waste that has to be vitrified for storage.

Furthermore, significant investment should be made into Carbon Dioxide Capture and Storage (CCS) technologies. CCS is a broad term that encompasses a number of technologies that can be used to capture CO2 from point sources, such as power plants and other industrial facilities; compress it; transport it mainly by pipeline to suitable locations; and inject it into deep subsurface geological formations for indefinite isolation from the atmosphere. As world energy demand increases, propelled by China’s exponential growth, much of the supply has come from fossil fuels. This has had adverse effects on climate change and global warming. Therefore clean coal will remain a critical tool for the future management of energy policy.

Finally and most important, renewable sources of energy should become an integral part of global energy needs. Wind energy, hydroelectric power, geothermal energy, tidal energy, biofuel, ethanol, and solar energy must be encouraged to help reduce the carbon footprint from fossil fuels. An August 2010 BusinessWeek article titled “Obama: Clean Energy's Venture Capitalist-in-Chief” commented on the administration’s aggressive policies towards promoting renewable energy. I think the President is making the right bets by promoting sustainable energy. The costs of inaction could be much worse.