Energy Lifecycle of Nuclear Power

The performance of Nuclear Power can also be measured by calculating the total energy required to build and run a Nuclear Power plant and comparing it to the total energy it produces. The following set of calculations is also taken from the independently audited, Vattenfall Environmental Product Declaration for its 3090 MW Forsmark power plant. A more detailed description is here. Vattenfall have also made available the aggregated data set as a spreadsheet. You can download it from here

The following table displays the source and the amount of energy required to produce 1 KW-Hr of electricity from the Forsmark power plant. The table includes the energy used in construction of the plant, mining the Uranium, enriching it, converting it to fuel, disposing the waste and decommissioning the plant. The Forsmark plant is assumed to run for 40 years. There is an additional 0.026 grams of Uranium consumed in generating this one KW-Hr of electricity. This 0.026 grams includes the Uranium used to generate power at Forsmark and the Uranium consumed by the French Nuclear Power plants that produced the electricity that enriched the Forsmark Fuel.

So the Forsmark Plant produces 93 times more energy than it consumes. Or put another way, the non-nuclear energy investment required to generate electricity for 40 years is repaid in 5 months. Normalized to 1 GigaWatt electrical capacity, the energy required tothe plant, which amounts to 4 Peta-Joules (PJ), which is repaid in 1.5 months. The energy required tois also 4 PJ and repaid in 1.5 months. In total this is less than 0.8% of the all the electrical energy produced by the plant.

The calculations of the operating energy costs include the energy required to mine and mill the Uranium. In the case of the Forsmark power plant some of the Uranium is sourced from the Olympic Dam mine in South Australia. This mine has a rather low Uranium concentration (0.05% by weight). A detailed and audited environmental description of the Olympic Dam mine is available here . A succinct description of the energy inputs of the mine is here . These data show that the Olympic Dam mine supplies enough Uranium for the generation of 26 GigaWatt-years of electricity each year (including the Uranium needed to run the power plants for enrichment). The energy consumed by the the mine is equivalent to 22% of a GigaWatt-Year. The energy gain is over a factor of 100. The Olympic Dam mine energy cost includes the energy required for mining and smelting it's huge Copper production.

Another Uranium source for Forsmark is the Rossing Mine in Namibia. A description of the operations of the mine is available here . The Rossing mine produced 3037 tonnes of Uranium in 2004, which is sufficient for 15 GigaWatt-years of electricity with current reactors. The energy used to mine and mill this Uranium was about 3% of a GigaWatt-year. Thus the energy produced is about 500 times more than the energy required to operate the mine.

It is worth noting that the widely quoted paper by Jan Willem Storm van Leeuwen and Philip Smith (SLS), which gives a rather pessimistic assessment of the Energy Lifecycle of Nuclear Power, assumes a far larger energy cost to construct and decommission a Nuclear Power plant (240 Peta-Joules versus 8 Peta-Joules(PJ)). The difference is that Vattenfall actually measured their energy inputs whereas Willem Storm van Leeuwen and Smith employed various theoretical relationships between dollar costs and energy consumed. This paper also grossly over-estimates the energy cost of mining low-grade Ores and also that the efficiency of extraction of Uranium from reserves would fall dramatically at ore concentrations below 0.05%. Employing their calculations predicts that the energy cost of extracting the Olympic Dam mine's yearly production of 4600 tonnes of Uranium would require energy equivalent to almost 2 one-GigaWatt power plants running for a full year (2 GigaWat-years). You can follow this calculation here . This is larger than the entire electricity production of South Australia and an order of magnitude more than the measured energy inputs.

The Rossing mine has a lower Uranium concentration (0.03% vs 0.05% by weight) than Olympic Dam and the discrepancy is even larger in the case of Rossing. Here SLS predict Rossing should require 2.6 Giga-Watt-Years of energy for mining and milling. The total consumption of all forms of energy in the country of Namibia is equivalent to 1.5 GigaWatt-Years, much less than the prediction for the mine alone. Furthermore, yearly cost of supplying this energy is over 1 billion dollars, yet the value of the Uranium sold by Rossing was, until recently, less than 100 million dollars per year. Since Rossing reports it's yearly energy usage to be 0.03 GigaWatt-years, SLS overestimates the energy cost of the Rossing mine by a factor of 80.

Additionally SLS predict that the yield of of Uranium extracted from low grade Ores will fall to 0 at concentrations of 0.0002% (2 ppm). The Olympic Dam mine extracts gold at high efficiency at concentrations of 0.0005% (5 ppm (parts per million)) and there are many other gold mines which produce gold profitably at this concentration. Given the huge Uranium reserves present at 5 ppm, it unlikely we will ever need mines that operate lower than this.

The energy cost of the Olympic Dam mine is the sum of all the operations for mining Copper, Uranium, Gold and other minerals. It is therefore the upper limit of the energy cost of extracting the Uranium alone. The Rossing mine which only produces Uranium, is a better measure of the energy cost future Uranium mines.

It is interesting to see what effect using the correct energy cost of 8 PJ for the construction, decommissioning and waste disposal of a power plants and the measured energy consumption of the Rossing mine has within the methodology of Willem Storm van Leeuwen and Smith. If we assume that the energy cost of extraction scales inversely with concentration and employ the Rossing experience as a benchmark, ore concentrations as low as 0.001% (10 ppm) provide an energy gain of 16. This also (and very unrealistically) assumes no further progress in mining technology or efficiency improvements in Nuclear Power operations over the course of hundreds of years. As shown here there is an estimated 1 trillion tonnes of Uranium at concentrations of 10 ppm or higher within the Earth's crust. This provides a resource over a factor of 300 times greater than predicted by Willem Storm van Leeuwen and Smith to be recoverable. So once the correct energy cost for plant construction and mining operations are used, the work of Willem Storm van Leeuwen and Smith imply that resource exhastion will not be a problem for Nuclear Power for the foreseeable future.

Storm and Smith have released a rebuttal of this argument. You can find this rebuttal here . We have responded in detail to the questions raised by Storm and Smith. You can find our reponse here . Storm and Smith have issued a rebuttal to our response. It is here . Our answer to this is here

Our additional investigations strengthen the conclusion that there is far more minable Uranium than predicted by Storm and Smith.