Renewables + Nuclear:  Partners in Decarbonization

(The following analysis is available for use for any purpose with attribution to the Climate Coalition.)

(Click to download a PDF of this information.)

“Nuclear or Renewables” is a false dichotomy when 83.1% of the world’s primary energy comes from fossil combustion.1 Our first concern for climate mitigation should be the carbon intensity of each energy resource, and how we may use them optimally for decarbonizing the global economy. Nuclear, solar, wind, hydro, and geothermal all have very low-life cycle greenhouse gas (GHG) emissions. However, the term “renewables” itself is incoherent, misleading, and discriminatory. Not all renewables have low climate, ecological, human health impacts; and some deemed non-renewables have said desirable attributes.

In this brief, we will only compare the attributes of nuclear energy to solar photovoltaic (PV) and wind power, which are the two modern renewables presently available for large scale deployment. In the public discourse, the fundamental technical and functional differences between wind, PV, and nuclear energy are being ignored. Nuclear, even if seen as equally valuable in decarbonization efforts, is then further discriminated against by exaggerating concerns about waste and safety. The resulting policy decisions lead to a sub-optimal mix of energy resources, putting the ultimate goal of decarbonization further out of reach: technically, logistically, financially, and politically.

Notice that electricity generation accounts for only 17.3% of global primary energy consumption. Decarbonizing transportation, building heating and cooling, and industrial processes is a much larger and harder task. While a portion of these sectors can be electrified (e.g. EVs, heat pumps), some cannot (e.g. steelmaking, aviation). Solar and wind produce only electricity whereas nuclear energy can serve as a high-heat source directly, skipping lossy conversion processes.

In addition, even with huge efficiency gains, global energy consumption will need to rise by 50% or more by 2050 to enable prosperity for all. Beyond reaching net-zero, we need to remove CO2 from the atmosphere to avoid continued warming for centuries. All these factors underline the scale and pace
of the clean energy challenge.

1) We need existing nuclear capacity to stay online to allow renewables to displace fossil electricity generation in the near-term.
2) Since nuclear technologies are necessary for economy-wide deep decarbonization, we need to accelerate development and deployment of an array of advanced reactor designs.

Solar and wind have a role to play now because the industry is mature and can deliver at scale. This is particularly relevant in early stages of decarbonization where intermittent output can replace large portions of fossil generation without curtailment, storage, and large transmission upgrades. However, there are political and logistical limits to the deployment of wind and solar energy, and the technical challenges rise exponentially as their share of generation increases.2 Cost-optimized energy system modeling shows wind and solar capacity rising first for moderate carbon emission reductions, and nuclear ramping up significantly as emissions approach zero. Today’s policies need to reflect this understanding and start multi-decadal plans to achieve reliable, affordable, and sustainable energy systems.

Emissions Low. 3 tonnes CO2-equivalent per gigawatt-hour (GWh) (Our World in Data) Low. Wind: 4 t CO2e/GWh. Solar: 5 t CO2/GWh.
Capital cost High capital cost for first-of-a-kind plants in the West. Moderate, and within budget, in the East/Asia. Relates to experience curve, not technology. Significant cost reductions realized with design standardization, high-volume deployment, and more expected with factory fabrication of Small Modular Reactors (SMRs). Low. Dramatic cost reductions over the last 15 years, especially in China (80% of global polysilicon, 98% of wafers & ingots, 7 of 10 top wind turbine manufacturers). Limited cost reductions expected going forward; possible cost increases if material supply chains tighten up.
Grid system integration cost Low. Medium to extremely high (see Intermittency). Long-distance transmission; energy storage; load balancing by conventional sources; curtailment for over-production; inefficient use of conventional baseload resources.
Land footprint 2.4 km2 per terawatt-hour generated (U.S. National Climate Assessment) Solar PV: 15x nuclear. Wind: 30x nuclear.
Build time Long in the West. In Asia, on schedule at ~3-5 years for Gen III. Build times for SMRs expected to be 18-36 months. Short for the solar/wind arrays. Permitting for long-distance transmission is causing lengthy delays. Large industrial arrays receiving increasing opposition from local communities. Increasingly long planning times for both onshore wind and PV deployment.
Grid function Baseload for Gen II-III, flexible/balancing operation in Europe. Gen IV typically capable of faster ramp/slew times for load balancing. Provides ancillary grid services (voltage/frequency regulation, spinning reserves). Mostly a conventional fuel-saver; although conventional sources may operate in less efficient modes for load balancing, which decreases fuel-saving. Typically, do not provide ancillary grid services.
Capacity factor limit 90+% in the U.S. Solar PV 10-25%.
Onshore Wind 25-35%. Offshore Wind 45-50%
Intermittency None. Fully dispatchable, reliable, and resilient generation. Gen III shuts down for scheduled maintenance every 18-24 months during low demand periods. Some Gen IV designs feature continuous operation for 10-20 years. Variable. Fluctuates with weather, time-of-day and seasonal variations. In some locations solar & wind deployments can complement each other. Intermittency is not a trivial matter. System reliability is currently accommodated by dispatchable gas combustion.
Applications Gen II-III: mostly electricity for grids. Some desalination and district heating. Gen III+-IV: electricity; industrial process heat; hydrogen for synthetic carbon-neutral liquid fuels; desalination; district heating; marine transport. Displacing fossil generation in early stages of decarbonization. Off-grid applications, mostly for solar PV. Beneficial where variability matches load (such as air conditioning). Not suited for 24/7 industrial heat/energy applications due to storage and conversion losses.
Material intensity Low. Approx. 1,000 tons/terawatt-hour. High. Wind ~10x nuclear. Solar PV ~16x nuclear.
Environmental impacts Very low. Quiet, small land footprint, some discharge of heated cooling water depending on plant design. Mining/processing impacts are proportional to Material intensity, discussed above. Moderate. Wind turbines kill bats, insects, and birds, mostly raptors and migratory birds; blade noise a potential annoyance & health concern for neighbors; industrial wind detracts from scenic vistas. Utility-scale solar PV arrays industrialize land, precluding former agricultural or natural habitat functions. Land lost for food production is possibly triggering habit loss for food production elsewhere. Mining/processing impacts are proportional to material intensity.
Marginal value of capacity addition Decreasing slowly. Nuclear is high-value energy with low system integration costs. Decreasing rapidly. As grid penetration level increases, integration costs increase, as well as curtailment losses, so incremental capacity provides less value.
Waste disposal Spent nuclear fuel mostly stored on-site. Almost zero public health risk. No injuries/deaths from 60 years of handling/storage of spent fuel globally. Waste stream is tiny in volume, can be recycled in fast reactors. Permanent geological repository needed, but not urgent. Obstacles are political and societal, not technological or safety related. Mostly no plans for final disposal of wind/solar hardware. Volume of material is high. Solar panels contain hazardous materials; recycling so far is prohibitively expensive.
Material supply chains Material and processing industries need to be scaled up, but there are no material bottlenecks anticipated, including for fission fuels. Gen IV fast spectrum reactors can achieve near 100% burnup of stored spent fuel, providing centuries of energy with no additional mining. Because of the high material intensity of solar/wind equipment, at large scale deployments shortfalls can be expected for availability and/or processing for rare earths, copper, high-purity silicon, etc. As demand increases for scarce materials, costs increase.
Environmental justice Human rights violations in mining largely a matter of the past (weapons programs during the Cold War). Global mining is internationally regulated and volume small and expected to decrease with Gen VI/fast-spectrum reactors. Power plant communities are well-off and proud of their plant. Large and growing need for metals (lithium, cobalt, copper, silicium, neodymium, etc.) without international oversight leads to human rights conflicts of land, pollution, water, child labor. Chinese slave labor a factor in dropping prices for PV panels. Energy colonization of rural areas for wind and PV deployment and transmission projects.

Further Graphical Support

Why Nuclear?

All four IPCC illustrative pathways consistent with a 1.5 °C warmer planet require nuclear energy generation to expand materially. Nuclear output in 2050 expands to 2-to-6 times the 2010 level, with our current fossil-fueled trajectory elevating the need further. From 2010 to 2019, renewable energy increased 67% while nuclear grew 1%.

What is the environmental footprint of each electricity source?

What are the system costs of decarbonization?

Sources: Eurostat, BP Stat Review, World Bank

Source: Brick & Thernstorm 2016

How safe are clean energy sources?

Source: Our World In Data

“There is no science-based evidence that nuclear energy does more harm to human health or to the environment than other… climate change mitigation [technologies].”

Source:  EU taxonomy for sustainable activities (2021)

What is the pace of low-carbon technology deployment?

Sources: BP Stat Review, World Bank



1 For reference, hydro generates 6.9% of global primary energy, nonhydro renewables 5.7%, and nuclear 4.3%. 2 Proposed solutions to overcome intermittency in highrenewable scenarios, such as green hydrogen, longduration storage, renewable jet fuel lack the necessary technological maturity, affordability, or scalability today.

2 Climate plans that hinge on unforeseen future technology breakthroughs and development along extremely optimistic trajectories are irresponsible as they carry a high risk of failure.