Clean, Reliable Energy

There is an ongoing debate about what constitutes clean energy. You even hear about “clean coal” in those discussions (I will get back to that later). We need to expand this debate to include “reliable” as part of the discussion. I define reliable as an energy source that is available to meet electricity demands any time of the day or night. If we define clean as a source that minimizes solid wastes and does not emit CO2, then electricity generated from nuclear power plants may be the only widely available source that qualifies as clean and reliable.

Let me explain with both words and graphs. First, everybody recognizes that the demand for electricity is not constant; we tend to use less at night than in the daytime. What most people don’t recognize is that even late at night, we still use 75% of the electricity consumed during normal working daytime hours (see figure 1). The data shown in figure 1 is important because it shows that even late at night, we consume a lot of electricity. That means a clean and reliable source of energy has to produce power all night long. Since we have no capacity for direct electricity storage on this scale, solar power doesn’t qualify as a reliable source of electricity for meeting our baseload requirements.

Wind is the other clean, renewable energy source, but it also has reliability problems. The “cut-in” wind speed (the speed when turbines can start producing usable power) is typically between 7-10 Mph. For most sites across the country, the wind speed varies considerably with the hour of the day, with minimum speeds between 1:00 and 5:00 AM. In addition to the hourly variations in wind speed, there are seasonal changes that affect the amount of energy available from wind power. For example, the National Climatic Data Center has collected data for 30 years and their information shows that the peak wind speeds for Fresno, CA are lowest in the winter months, and highest in the spring and summer. Although not an ideal wind site, the wind profiles for Fresno are similar to profiles at other sites around the country. The energy produced by these systems is not constant, and during many hours of the day they drop below the cut-in threshold. Figure 2 shows average hourly wind speed data for Fresno, California in July of 2009. As shown on this plot, the average wind speed does not cross the “cut-in” threshold until just after 3:00 in the afternoon. The wind speed allows energy generation during the peak demand hours of 5:00 – 8:00 PM, but would contribute nothing to the power requirements between 3:00 AM and 4:00 PM. The fact that wind power systems don’t burn any fuel while they are operating qualifies them as clean energy sources, but they can’t be relied to meet baseload electricity demands. There has been a lot effort to develop grid scale energy storage systems (massive batteries) so that power produced by wind turbines when the wind blows could be used at other times of the day, but none of that effort has produced a viable sulution. For the foreseeable future, wind will remain an attractive and clean way of helping to meet peak power needs, but won’t contribute to the supply of baseload electricity.

Now, what happens when we overlay some of the information we now have about wind energy availability on top of the electricity demand graph and see what conclusions can be drawn. The data on electricity demand came from the California ISO website referenced in end note 1, and the wind data came from the National Oceanic and Atmospheric Administration’s National Data Center referenced in endnote 3. The scale for measuring power demand is VERY different than the scale for measuring wind speed, so each data stream is plotted against a separate vertical axis in Figure 3. The absolute values in the two plot lines aren’t important, but the trends certainly are very critical, and very clear when plotted together. Although the wind begins to blow hard enough to make power just before peak demand begins, there is a significant time period where the demand is increasing from baseline levels and when there is no recoverable wind energy. From this data, the average wind energy is July is unable to produce power for 50% of the day, and that low point in energy production coincides with high, steady demand during productive daylight hours. In addition, the average wind strength is greatest during the time of day that demand for electricity is dropping rapidly. Clearly, this does not represent a reliable source of power. When you factor in the understanding that solar power does not create any electricity at night, and only minimal power during the first and last three hours of daylight when the sun is at a low angle in the sky and the inevitable conclusion is that the two cleanest sources of energy are not reliable sources. In fact, an energy production strategy that focused on wind and solar would require constructing a completely redundant system of other energy sources to pick up the load when both the wind and sun are absent. That doubling of the installed capacity to provide reliability would raise electricity rates to unaffordable levels.

Now, back to coal. Coal certainly produces reliable energy. The fuel source is abundant in the US and burning it in a traditional fossil plant produces dependable energy on demand, 24 hours a day. Coal’s availability and reliability is why it is used to produce 30% of our electricity. There is a lot of talk about “clean coal”, but that talk centers on capturing and storing CO2. Currently, a 1,000 MW(e) coal plant burns about 3.4 million tons of coal per year when operating at a 90% capacity factor. Burning that coal requires 32 million tons of air for combustion and produces 8.8 million tons of CO2 (yes, with the amount of air consumed, a coal plant puts out more tons of CO2 than the tons of coal burned). That is a huge amount of CO2 to try and capture for storage, but let’s assume it can be done. Does that make coal clean? Not by a long shot. In addition to the CO2 produced from burning that much coal, the waste stream also includes 685,000 tons of fly ash, bottom ash and slag. Toxic materials originally present in the coal are concentrated in this ash when the carbon burns off. The GAO reported that between 2000 & 2006, the power industry deposited more than 124 million pounds of six toxic pollutants (arsenic, chromium, lead, nickel, selenium, and thallium) in ash sludge ponds. A major example of what can go wrong with ash storage can be seen in the 2008 failure of the retention pond for TVA’s Kingston Coal Plant in Tennessee. The official estimate is that 5.4 million cubic yards of sludge were released from the 84-acre “containment area”. The spill covered surrounding land with up to six feet (1.8 m) of sludge as shown in Figure 4. The EPA’s approved clean-up plan now estimates the cost of the clean-up to be $268.2 million. On March 6, 2009 Duke University submitted a Survey of the Potential Environmental and Health Impacts in the Immediate Aftermath of this Coal Ash Spill. That survey showed enrichment of trace elements (including strontium, arsenic, barium, berrylium, cadmium, chromium, lithium, lead, mercury, nickel, and thallium) in samples of sediments and river water. Despite the fact that 26 reporting facilities cited spills or unpermitted releases from a total of 35 surface ash impoundments within the last 10 years, the EPA does not directly regulate coal combution residue disposal in surface impoundments or landfills. The exact number of CCR surface impoundments at utility coal fired power plants is not known, and no industry organization or government agency tracks this information.
If we are consistent with the definition of “clean” energy as a source that minimizes solid waste and CO2 production then coal power can’t be called clean, even if methods for carbon capture and storage are worked out.

Now, let’s compare the operation of a nuclear power plant that produces the same amount of electricity as the coal plant described above, 1,000 MW(e) constantly for 90% of the year. With the same overall power output, the nuclear plant only consumes 19 tons of nuclear fuel, compared to 3.4 million tons of coal required for the fossil fuel plant. Perhaps more importantly, the effluent from that nuclear plant’s operations is also only 19 tons. Since nuclear fuel does produce its power by a burning process, no air is needed, no oxygen is consumed and the 8.8 million tons of CO2 produced by a comparable coal plant is avoided. Yes, the waste requires careful management, but that has always been assured. The used fuel is placed in massive welded steel containers that are surrounded with reinforced concrete structures that are constantly monitored. This focus on safe nuclear waste management in the United States explains why there has never been a release of spent fuel into the environment here. Even under the severe accident conditions like those at Three Mile Island, all of the spent fuel has been contained. When compared to the annual storage of 685,000 tons of ash wastes from a similarly sized coal plant that are stored as sludge behind earthen dams, it is easy to understand that there is a significant difference in the cleanliness of nuclear plants compared to coal.

So, where can you get clean electricity in a reliable way? Based solely on the facts, nuclear power is a resource that must be considered. It provides reliable power 24 hours a day, emits no CO2 from power production, produces minimal solid wastes that are safely and securely managed and does not require any new technology to deploy more plants today. When contrasted with other clean technologies it is far more reliable and the cleanliness of nuclear far surpasses other reliable sources of electricity like coal. Let’s protect the environment and assure ample supplies of electricity to meet our growing baseload demand by increasing the size of the fleet of nuclear power plants. This can, and should be done in parallel with expanding the use of other clean energy sources that can help meet peak energy demands.

[1] From: a source of definitions and background information
on energy production.

[2] From the NOAA’s National Data Center at:

[3] From the Energy Information Administration at:

[4] From GAO report: “Coal Combustion Residue: Status of EPA’s Efforts to Regulate Disposal” available at:

[5] From EPA fact sheet available at:

[6] From Duke University testimony to the Subcommittee on Water Resources and Environment, U.S. House of
Representatives available at:

[7] Derived from EIA data on energy generated by nuclear plants at and EIA data on used fuel discharged by nuclear plants at

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Yucca Mountain Laid To Rest

On September 30, 2010, the DOE Office of Civilian Radioactive Waste Management (OCRWM) ceased to exist.  This was the Office established by Congress to study, design, license, construct and operate a repository for the nation’s spent nuclear fuel.  The reasons for its demise have been discussed at length in the trade press and in the news media.  Much of the credit for the end of Yucca Mountain (YM) is given to the Senate Majority Leader, Harry Reid, who built his career around opposing construction of a repository in Nevada.

Although that viewpoint is easy to understand given the political nature of the YM project from the begining, YM had withstood the opposition of Nevada previously.  When the site was first recommended by DOE in 2002, Nevada vetoed the recommendation, but was overruled by a significant majority vote in both the House and Senate.

What changed? In the initial vote to approve YM, it enjoyed a coalition of support that was broad and deep.  The nuclear industry, states with waste in storage, Congress and the rural counties in Nevada where the repository would be built all supported the program.  In the three years immediately following the Yucca site recommendation, OCRWM made a number of mistakes, causing supporters to lose faith. Certification of the Licensing Support Network was struck down when it was challenged by Nevada and submittal of the License Application (LA) to the US Nuclear Regulatory Commission (NRC) suffered numerous delays.

Although OCRWM made significant progress in 2008 when the LA was submitted to the NRC, and docketed, major supporters had already shifted their focus.  One of the drivers for broad support was the “confidence rule” first issued by the NRC in 1984.  The confidence rulemaking responded to legal challenges over the environmental impact of nuclear energy absent waste disposal capability. The NRC rule established expectations for future licensing of nuclear power plants.  Two key parts of the rule were requiring reasonable confidence that the wastes could, and would in due course be disposed of safely; and that wastes could be stored safely in the interim.

As faith in Yucca waned, supporters lobbied for a shift in the focus of the confidence rule. A rule based only on safe, longer term storage, would obviate the need for disposal at YM. The rule was updated on 9/15/2010 with this shift in the basis for continued licensing activities.

As expected, legal challenges to this change were soon raised. The plaintiffs complained that the changed rule did not adhere to NEPA requirements for a thorough environmental impact analysis because no detailed study of long term storage had ever been done.  This was raised as a particular concern for high burn-up fuels.  The plaintiffs won that challenge and the NRC is still working on a supplement to their environmental analyses to support the proposed rule change (as of 10/18/2013).  

Even after completion of an analysis of the impacts associated with long term storage, a new final rule making supporting continued storage is likely to be challenged in the courts again.  There is an argument that waste confidence is based on the eventual ability to dispose of these wastes, not on the ability to store them safely for very long periods of time.  The fact that eventual disposal of these wastes has actually taken several steps backwards rather than progressing could suggest the plaintiffs have a viable rationale for their follow-on suit. That will be an interesting case to follow.

Some have suggested that the nuclear power industry should do more to support development of a repository.  Pressing their Congressional representatives to support aggressive development of a repository (be it Yucca Mountain, or a new site based on the consensus of the host community) would be a good place to start.  There is a belief that such action would be in the utilities best interests.  Unfortunately, a cold calculation of the energy situation may suggest a different approach.  Right now, the operational costs of small merchant nuclear plants are not competitive with natural gas fired plants, and they can’t follow the loads on the grid as easily as a gas plant can.  Shutting down a plant before the end of its useful life involves significant costs.  Funds for decommissioning the plant are collected during the plant’s operating life.  If the plant is shut down early, insufficient decommissioning funds may be available.  This can be a big problem, but the government may provide a solution for them!

The utilities have contracts with the federal government to take their spent fuel and dispose of it.  The government was supposed to start collecting the fuel in 1998.  When the government failed to pick up the spent fuel on time, the utilities sued for partial breach of contract and won their suits. Based on the government’s failure to pick up the fuel for disposal, taxpayers are on the hook for about $500,000,000 per year to cover the continued storage costs at utility sites.  Now, take this logic one step further.  If the NRC loses its waste confidence battle because there is no progress on disposal, it may have to call for the closure of all of the nuclear plants in the US.  If that happens, whose fault is it?  Again, the government is responsible for disposing of these wastes, so any requirement to shut down plants based on a lack of disposal capability would fall on the government again. If forced to shut down before their operating licenses normally expire, the utilities could sue for both their decommissioning costs and the cost of replacement power!  Based on the precedents set by the storage liability, they would have a good chance of winning those challenges.

Loss of broad support is what killed YM, not political pressure alone. The fact that neither the utility industry nor their lobbying group are actively pressing for a solution suggests the status quo is fine with them.  If America loses its nuclear industry, it will be due to the lack of actions from its supporters as much as from the actions of its detractors.  It will be one more technology originated in the US that we wind up giving away to the rest of the world along with the jobs that once went with it.  Right now the incentives are not aligned to encourage anything more than minor research on nuclear power in this country.  If key policy makers want to change that, they need to work tirelessly on resolving all issues affecting the full nuclear life cycle, including disposal.  

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Welcome to RAMTASC Ramblings.  In this blog I will explore facts and myths about radioactive material transportation and storage in the context of current policy developments.  My first editorial is about the framework of support needed for the long term success of any solution to managing used nuclear fuel.  Stop in often and provide your perspectives on the topics I explore.

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