|Fig. 1: Projected Levelized Cost of Energy for plants entering service based on projections by the U.S. Energy Information Administration. [2,3] These numbers are estimates, and actual costs will be influenced by a number of outside factors. (Source: L. Asperger)|
The world's energy landscape is continually evolving. Climate change concerns have spurred a gradual but strong transition away from high carbon-emitting energy sources, and solar photovoltaics are emerging as the leading contender to power the energy grid of the future. Although fossil fuels still dominate the grid, the technological and economic momentum of solar is undeniable. While much of the world appears bent on ultimately phasing out fossil fuels as much as possible, the future of nuclear energy is arguably a little hazier. The economic outlook for nuclear energy overall is less than amazing. However, recent research has looked into the potential for hybrid power plants that couple nuclear power to renewable energy sources. Though unproven, this technology could address some of the most significant drawbacks of both nuclear and renewable energy sources.
There are many economic issues that present barriers to the development of new nuclear capacity moving forward. Because the upfront capital requirements are demanding, interest from private investors is lower than other energy sources. Cost uncertainties often arise regarding construction time and meeting regulatory standards. As a result, there are far fewer plans to construct new nuclear plants in liberalized economies than in centrally-planned economies such as those Asia. 
The cost of solar photovoltaics have gone down massively over the past four decades. Nuclear, on the other hand, has not fared quite as well, seeing minimal cost reductions in recent years. Although assessing the cost of energy sources is difficult do precisely, one way to get a reasonable sense of the costs is using the Levelized Cost of Electricity (LCOE), which essentially takes into account the total cost of the construction, operation and maintenance of an energy project over its entire lifetime. As shown in Fig. 1, in 2014, the Energy Information Administration (EIA) estimated the LCOE of new resources or plants entering service in 2019 at $86.1/MWh for nuclear and $118.6/MWh for solar PV.  Just three years later, the EIA estimated the LCOE of new resources or plants entering service in 2022 at $96.2/MWh for nuclear and $58.1/MWh for solar PV.  This represents over a 10% increase in cost for nuclear and roughly a 50% decrease in cost for solar. It is important to remember that these numbers are just estimates, and there are many political factors such as recent legislation pushed by the Trump administration that could slow the gains of solar energy. However, the trend certainly does not bode well for the role of traditional nuclear plants in the energy grid of the future.
Despite the strong and promising growth of renewables recently, there is still a long way to go before renewables can overtake fossil fuels. Additionally, the two most promising forms of renewable energy, solar and wind, both suffer from a common drawback - intermittent and fluctuating supply. With few cheap and efficient energy storage options available, this presents a serious challenge. Nuclear, on the other hand, is a reliable carbon-free energy source that generates a steady, consistent supply of power with the drawback that it cannot easily adjust its rate of energy generation. If nuclear and renewable energy sources could be combined in an effective way, they might be able to counteract each other's shortcomings to achieve a performance better than was possible independently. A hybrid renewable plant is one that combines a form of renewable energy with a nonrenewable form.
There are many concepts for a potential integrated nuclear-renewable hybrid plant. One possibility is to combine a small nuclear reactor with a concentrated solar-thermal plant. In this design, heat from the solar thermal plant is used to superheat the nuclear steam. In a simulation of such a design, the overall efficiency of a nuclear plant was increased from 33.9% to 39.7%.  Another idea is to combine a small nuclear reactor with a biomass production unit as well as a wind farm. The nuclear plant continuously generates heat which is used either for electricity generation or biomass production depending on the electricity demand and the supply of wind energy at any given time. Surplus electricity generated from the wind farm can also be used to power an integrated hydrogen production facility.  This concept has many advantages because it both has the capacity to always meet demand and also ensure that minimal energy is wasted. A final noteworthy design is a combined nuclear and geothermal power plant, where the nuclear cores are positioned deep underground in a hot dry rock zone. The activity of the nuclear reactor enhances the temperature differential underground that powers the geothermal plant. 
It remains to be seen whether the world will ever see a nuclear-renewable hybrid power plant. Though the technology already exists to build one, there are many questions still to be answered, and further research and development is required towards integration for any of the previously mentioned designs.
However, if implemented effectively, such systems could help address significant drawbacks of each source individually. Perhaps the most important benefit is the reliability nuclear energy can provide over renewable energy. Challenges still remain, especially regarding load-following ability, which neither solar nor nuclear can match in comparison with fossil fuels. As energy storage technology improves, however, these concerns can gradually be mitigated as well.
© Luke Asperger. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 C. Difiglio and . Wanner, "Economics of Nuclear Power in Liberalized Power Markets," in International Seminars on Nuclear War and Planetary Emergencies, 45th Session, ed. by R. Ragaini (World Scientific, 2013), pp.271-287.
 "Levelized Cost and Levelized Avoided Cost of New Generation Resources in the Annual Energy Outlook 2014," U.S. Energy Information Administration, April 2014.
 "Levelized Cost and Levelized Avoided Cost of New Generation Resources in the Annual Energy Outlook 2018," U.S. Energy Information Administration, March 2018.
 A. Borissova, "Analysis and Synthesis of a Hybrid Nuclear-Solar Power Plant" BgNS Trans. 20, 58 (2015).
 S, Suman, "Hybrid Nuclear-Renewable Energy Systems: A Review," J. Clean. Prod. 181, 166 (2018).