Whether nuclear power should be considered a form of renewable energy is an ongoing subject of debate. Statutory definitions of renewable energy usually exclude many present nuclear energy technologies, with the notable exception of the state of Utah.[1] Dictionary-sourced definitions of renewable energy technologies often omit or explicitly exclude mention of nuclear energy sources, with an exception made for the natural nuclear decay heat generated within the Earth.[2][3]

The most common fuel used in conventional nuclear fission power stations, uranium-235 is "non-renewable" according to the Energy Information Administration, the organization however is silent on the recycled MOX fuel.[3] Similarly, the National Renewable Energy Laboratory does not mention nuclear power in its "energy basics" definition.[4]

In 1987, the Brundtland Commission (WCED) classified fission reactors that produce more fissile nuclear fuel than they consume (breeder reactors, and if developed, fusion power) among conventional renewable energy sources, such as solar power and hydropower.[5] The American Petroleum Institute does not consider conventional nuclear fission renewable, but considers breeder reactor nuclear fuel renewable and sustainable, and while conventional fission leads to waste streams that remain a concern for millennia, the waste from efficiently recycled spent fuel requires a more limited storage supervision period of about thousand years.[6][7][8] The monitoring and storage of radioactive waste products is also required upon the use of other renewable energy sources, such as geothermal energy.[9]

Definitions of renewable energy

Renewable energy flows involve natural phenomena, which with the exception of tidal power, ultimately derive their energy from the sun (a natural fusion reactor) or from geothermal energy, which is heat derived in greatest part from that which is generated in the earth from the decay of radioactive isotopes, as the International Energy Agency explains:[10]

Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from sunlight, wind, oceans, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources.

Renewable energy resources exist over wide geographical areas, in contrast to other energy sources, which are concentrated in a limited number of countries.[10]

In ISO 13602-1:2002, a renewable resource is defined as "a natural resource for which the ratio of the creation of the natural resource to the output of that resource from nature to the technosphere is equal to or greater than one".

Conventional fission, breeder reactors as renewable

Nuclear fission reactors are a natural energy phenomenon, having naturally formed on earth in times past, for example a natural nuclear fission reactor which ran for thousands of years in present-day Oklo Gabon was discovered in the 1970s. It ran for a few hundred thousand years, averaging 100 kW of thermal power during that time.[11][12]

Conventional, human manufactured, nuclear fission power stations largely use uranium, a common metal found in seawater, and in rocks all over the world,[13] as its primary source of fuel. Uranium-235 "burnt" in conventional reactors, without fuel recycling, is a non-renewable resource, and if used at present rates would eventually be exhausted.

A cutaway model of the 2nd most powerful presently operating fast breeder reactor in the world. The (BN-600), at 600 MW of nameplate capacity is equivalent in power output to a natural gas CCGT. It dispatches 560 MW to the Middle Urals power grid. Construction of a second breeder reactor, the BN-800 reactor was completed in 2014.

This is also somewhat similar to the situation with a commonly classified renewable source, geothermal energy, a form of energy derived from the natural nuclear decay of the large, but nonetheless finite supply of uranium, thorium and potassium-40 present within the Earth's crust, and due to the nuclear decay process, this renewable energy source will also eventually run out of fuel. As too will the Sun, and be exhausted.[14][15]

Nuclear fission involving breeder reactors, a reactor which breeds more fissile fuel than they consume and thereby has a breeding ratio for fissile fuel higher than 1 thus has a stronger case for being considered a renewable resource than conventional fission reactors. Breeder reactors would constantly replenish the available supply of nuclear fuel by converting fertile materials, such as uranium-238 and thorium, into fissile isotopes of plutonium or uranium-233, respectively. Fertile materials are also nonrenewable, but their supply on Earth is extremely large, with a supply timeline greater than geothermal energy. In a closed nuclear fuel cycle utilizing breeder reactors, nuclear fuel could therefore be considered renewable.

In 1983, physicist Bernard Cohen claimed that fast breeder reactors, fueled exclusively by natural uranium extracted from seawater, could supply energy at least as long as the sun's expected remaining lifespan of five billion years.[16] This was based on calculations involving the geological cycles of erosion, subduction, and uplift, leading to humans consuming half of the total uranium in the Earth's crust at an annual usage rate of 6500 tonne/yr, which was enough to produce approximately 10 times the world's 1983 electricity consumption, and would reduce the concentration of uranium in the seas by 25%, resulting in an increase in the price of uranium of less than 25%.[16][17]

Proportions of the isotopes, U-238 (blue) and U-235 (red) found in natural uranium, versus grades that are enriched. light water reactors and the natural uranium capable CANDU reactors, are primarily powered only by the U-235 component, failing to extract much energy from U-238. While by contrast uranium breeder reactors mostly use U-238/the primary constituent of natural uranium as their fuel.[18]

Advancements at Oak Ridge National Laboratory and the University of Alabama, as published in a 2012 issue of the American Chemical Society, towards the extraction of uranium from seawater have focused on increasing the biodegradability of the materials used reducing the projected cost of the metal if it was extracted from the sea on an industrial scale. The researchers' improvements include using electrospun Shrimp shell Chitin mats that are more effective at absorbing uranium when compared to the prior record setting Japanese method of using plastic amidoxime nets.[19][20][21][22][23][24] As of 2013 only a few kilograms (picture available) of uranium have been extracted from the ocean in pilot programs and it is also believed that the uranium extracted on an industrial scale from the seawater would constantly be replenished from uranium leached from the ocean floor, maintaining the seawater concentration at a stable level.[25] In 2014, with the advances made in the efficiency of seawater uranium extraction, a paper in the journal of Marine Science & Engineering suggests that with, light water reactors as its target, the process would be economically competitive if implemented on a large scale.[26] In 2016 the global effort in the field of research was the subject of a special issue in the journal of Industrial & Engineering Chemistry Research.[27][28]

In 1987, the World Commission on Environment and Development (WCED), an organization independent from, but created by, the United Nations, published Our Common Future, in which a particular subset of presently operating nuclear fission technologies, and nuclear fusion were both classified as renewable. That is, fission reactors that produce more fissile fuel than they consume - breeder reactors, and when it is developed, fusion power, are both classified within the same category as conventional renewable energy sources, such as solar and falling water.[5]

Presently, as of 2022, only 2 breeder reactors are producing industrial quantities of electricity, the BN-600 and BN-800. The retired French Phénix reactor also demonstrated a greater than one breeding ratio and operated for ~30 years, producing power when Our Common Future was published in 1987.

To fulfill the conditions required for a nuclear renewable energy concept, one has to explore a combination of processes going from the front end of the nuclear fuel cycle to the fuel production and the energy conversion using specific fluid fuels and reactors, as reported by Degueldre et al. (2019).[29] Extraction of uranium from a diluted fluid ore such as seawater has been studied in various countries worldwide. This extraction should be carried out parsimoniously, as suggested by Degueldre (2017).[30] An extraction rate of kilotons of U per year over centuries would not modify significantly the equilibrium concentration of uranium in the oceans (3.3 ppb). This equilibrium results from the input of 10 kilotons of U per year by river waters and its scavenging on the sea floor from the 1.37 exatons of water in the oceans.[31] For a renewable uranium extraction, the use of a specific biomass material is suggested to adsorb uranium and subsequently other transition metals. The uranium loading on the biomass would be around 100 mg per kg. After contact time, the loaded material would be dried and burned (CO2 neutral) with heat conversion into electricity.e.g.[32] The uranium ‘burning’ in a molten salt fast reactor helps to optimize the energy conversion by burning all actinide isotopes with an excellent yield for producing a maximum amount of thermal energy from fission and converting it into electricity. This optimisation can be reached by reducing the moderation and the fission product concentration in the liquid fuel/coolant. These effects can be achieved by using a maximum amount of actinides and a minimum amount of alkaline/earth alkaline elements yielding a harder neutron spectrum. Under these optimal conditions the consumption of natural uranium would be 7 tons per year and per gigawatt (GW) of produced electricity.e.g.[29] The coupling of uranium extraction from the sea and its optimal utilisation in a molten salt fast reactor should allow nuclear energy to gain the label renewable. In addition, the amount of seawater used by a nuclear power plant to cool the last coolant fluid and the turbine would be ~2.1 giga tons per year for a fast molten salt reactor, corresponding to 7 tons of natural uranium extractable per year. This practice justifies the label renewable.[33]

Fusion fuel supply

If it is developed, fusion power would provide more energy for a given weight of fuel than any fuel-consuming energy source currently in use,[34] and the fuel itself (primarily deuterium) exists abundantly in the Earth's ocean: about 1 in 6500 hydrogen (H) atoms in seawater (H2O) is deuterium in the form of (semi-heavy water).[35] Although this may seem a low proportion (about 0.015%), because nuclear fusion reactions are so much more energetic than chemical combustion and seawater is easier to access and more plentiful than fossil fuels, fusion could potentially supply the world's energy needs for millions of years.[36][37]

In the deuterium + lithium fusion fuel cycle, 60 million years is the estimated supply lifespan of this fusion power, if it is possible to extract all the lithium from seawater, assuming current (2004) world energy consumption.[38] While in the second easiest fusion power fuel cycle, the deuterium + deuterium burn, assuming all of the deuterium in seawater was extracted and used, there is an estimated 150 billion years of fuel, with this again, assuming current (2004) world energy consumption.[38]

Legislation in the United States

If nuclear power were classified as renewable energy (or as low-carbon energy), additional government support would be available in more jurisdictions, and utilities could include nuclear power in their effort to comply with Renewable portfolio standard (RES).

In 2009, the State of Utah passed the "Renewable Energy Development Act" which in part defined nuclear power as a form of renewable energy.[1]

See also

References

  1. 1 2 Utah House Bill 430, Session 198
  2. ↑ "Renewable energy: Definitions from Dictionary.com". Dictionary.com website. Lexico Publishing Group, LLC. Retrieved 2007-08-25.
  3. 1 2 "Renewable and Alternative Fuels Basics 101". Energy Information Administration. Retrieved 2007-12-17.
  4. ↑ "Renewable Energy Basics". National Renewable Energy Laboratory. Archived from the original on 2008-01-11. Retrieved 2007-12-17.
  5. 1 2 Brundtland, Gro Harlem (20 March 1987). "Chapter 7: Energy: Choices for Environment and Development". Our Common Future: Report of the World Commission on Environment and Development. Oslo. Retrieved 27 March 2013. Today's primary sources of energy are mainly non-renewable: natural gas, oil, coal, peat, and conventional nuclear power. There are also renewable sources, including wood, plants, dung, falling water, geothermal sources, solar, tidal, wind, and wave energy, as well as human and animal muscle-power. Nuclear reactors that produce their own fuel ('breeders') and eventually fusion reactors are also in this category
  6. ↑ American Petroleum Institute. "Key Characteristics of Nonrenewable Resources". Retrieved 2010-02-21.
  7. ↑ pg 15 see SV/g chart, without "TRU" or trans-uranics being present, the radioactivity of the waste decays to levels similar to the original uranium ore in about 300–400 years
  8. ↑ MIT spent fuel radioactivity comparison, table 4.3
  9. ↑ http://www.epa.gov/radiation/tenorm/geothermal.html Geothermal Energy Production Waste.
  10. 1 2 IEA Renewable Energy Working Party (2002). Renewable Energy... into the mainstream, p. 9.
  11. ↑ Meshik, A. P. (November 2005). "The Workings of an Ancient Nuclear Reactor". Scientific American. 293 (5): 82–6, 88, 90–1. Bibcode:2005SciAm.293e..82M. doi:10.1038/scientificamerican1105-82. PMID 16318030.
  12. ↑ Gauthier-Lafaye, F.; Holliger, P.; Blanc, P.-L. (1996). "Natural fission reactors in the Franceville Basin, Gabon: a review of the conditions and results of a "critical event" in a geologic system". Geochimica et Cosmochimica Acta. 60 (25): 4831–4852. Bibcode:1996GeCoA..60.4831G. doi:10.1016/S0016-7037(96)00245-1.
  13. ↑ "Nuclear - Energy Explained, Your Guide to Understanding Energy - Energy Information Administration".
  14. ↑ The end of the Sun
  15. ↑ Earth Won't Die as Soon as Thought
  16. 1 2 Cohen, Bernard L. (January 1983). "Breeder reactors: A renewable energy source" (PDF). American Journal of Physics. 51 (1): 75–76. Bibcode:1983AmJPh..51...75C. doi:10.1119/1.13440. Archived from the original (PDF) on 2007-09-26. Retrieved 2007-08-03.
  17. ↑ McCarthy, John (1996-02-12). "Facts from Cohen and others". Progress and its Sustainability. Stanford. Archived from the original on 2007-04-10. Retrieved 2007-08-03.
  18. ↑ Cohen, Fuel of the Future, Chapter 13
  19. ↑ "Nanofibers Extract Uranium from Seawater Hidden within the oceans, scientists have found a possible way to power nuclear reactors long after uranium mines dry up". Scientific American.
  20. ↑ "abstracts from papers for the ACS Extraction of Uranium from Seawater conference".
  21. ↑ "Advances in decades-old dream of mining seawater for uranium".
  22. ↑ "Shrimp 30,000 volts help UA start up land 1.5 million for uranium extraction. 2014".
  23. ↑ Details of the Japanese experiments with Amidoxime circa 2008, Archive.org
  24. ↑ Confirming Cost Estimations of Uranium Collection from Seawater, from Braid type Adsorbent. 2006 Archived 2008-06-12 at the Wayback Machine
  25. ↑ "The current state of promising research into extraction of uranium from seawater — Utilization of Japan's plentiful seas".
  26. ↑ Development of a Kelp-Type Structure Module in a Coastal Ocean Model to Assess the Hydrodynamic Impact of Seawater Uranium Extraction Technology. Wang et al. J. Mar. Sci. Eng. 2014, 2(1), 81-92; doi:10.3390/jmse2010081
  27. ↑ Uranium Seawater Extraction Makes Nuclear Power Completely Renewable. Forbes. James Conca. July 2016
  28. ↑ April 20, 2016 Volume 55, Issue 15 Pages 4101-4362 In this issue:Uranium in Seawater
  29. 1 2 Claude Degueldre, Richard James Dawson, Vesna Najdanovic-Visak Nuclear fuel cycle, with a liquid ore and fuel: toward renewable energy, Sustainable Energy and Fuels 3 (2019) 1693-1700. https://doi.org/10.1039/C8SE00610E
  30. ↑ Claude Degueldre, Uranium as a renewable for nuclear energy, Progress in Nuclear Energy, 94 (2017) 174-186. https://doi.org/10.1016/j.pnucene.2016.03.031
  31. ↑ M.R. Palmer, J.M. Edmond, Uranium in river water, Geochimica et Cosmochimica Acta, 57 (1993) 4947-4955, https://doi.org/10.1016/0016-7037(93)90131-F
  32. ↑ R. K. Srivastava, N. P. Shetti, K. Raghava Reddy, E. E. Kwon, M. N. Nadagouda, T. M. Aminabhavi,Biomass utilization and production of biofuels from carbon neutral materials,Environmental Pollution, 276, (2021) 116731, https://doi.org/10.1016/j.envpol.2021.116731.
  33. ↑ Renewable energy
  34. ↑ Robert F. Heeter; et al. "Conventional Fusion FAQ Section 2/11 (Energy) Part 2/5 (Environmental)". Archived from the original on 2001-03-03.
  35. ↑ Dr. Frank J. Stadermann. "Relative Abundances of Stable Isotopes". Laboratory for Space Sciences, Washington University in St. Louis. Archived from the original on 2011-07-20.
  36. ↑ J. Ongena and G. Van Oost. "Energy for Future Centuries" (PDF). Laboratorium voor Plasmafysica– Laboratoire de Physique des Plasmas Koninklijke Militaire School– Ecole Royale Militaire; Laboratorium voor Natuurkunde, Universiteit Gent. pp. Section III.B. and Table VI. Archived from the original (PDF) on 2013-10-14.
  37. ↑ EPS Executive Committee. "The importance of European fusion energy research". The European Physical Society. Archived from the original on 2008-10-08.
  38. 1 2 Ongena, J; G. Van Oost (2004). "Energy for future centuries - Will fusion be an inexhaustible, safe and clean energy source?" (PDF). Fusion Science and Technology. 2004. 45 (2T): 3–14. Bibcode:2004FuST...45....3O. doi:10.13182/FST04-A464. S2CID 15368449. Archived from the original (PDF) on 2013-10-14.
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