The energy transition is one of the most pressing challenges of our time, and the comparison between nuclear energy and renewable sources such as solar, wind, and hydropower has become a hot topic. When analyzing the latest data and the arguments that dominate public and scientific debate, it is essential to understand how each energy source ranks in terms of cost, efficiency, environmental impact, and future potential.
This article compiles and expands on information from the best studies, reports, and specialized portals, focusing on the Spanish context but with global data. This article offers a clear and up-to-date overview of the advantages and disadvantages of nuclear energy versus renewables, while also integrating technical and socioeconomic nuances that often go unnoticed in many analyses.
Current overview of electricity generation in Spain and around the world
Renewable energy sources have substantially increased their share of the energy mix , both nationally and internationally. According to the latest data from Red Eléctrica de España (REE), in January 2024, renewables accounted for 52,1% of the electricity generated in the country, equivalent to more than 12.200 GWh. Wind power leads the way with 24,6% , followed by hydropower (17,4%) and solar, which, although its percentage is not specified, has experienced meteoric growth in recent years. Nuclear power, meanwhile, accounted for 22% of the supply, falling behind the combined total of the main renewable sources.
This shift in leadership within the energy landscape is no coincidence. Technological advancements, cost competitiveness, and regulatory incentives have boosted solar and wind power in particular, making them more affordable and accessible to both investors and consumers.
What do we mean by renewable energies and how are they classified?
Renewable energies are those obtained from inexhaustible natural sources or those with the capacity to regenerate in the short term. The main ones include wind, solar (photovoltaic and thermal), and hydroelectric power. Biomass and geothermal energy complete the group, although their relative importance is less in the Spanish and European context.
- Clean: They generate very little waste and do not emit greenhouse gases in their operations.
- Inexhaustible: They come from sources such as the sun, wind or water, whose natural flow is not depleted by human consumption.
- Native: They allow us to take advantage of the resources available in each territory, reducing dependence on foreign countries.
- No hazardous waste: Unlike nuclear power, they do not leave behind long-lasting toxic or radioactive materials.
In contrast, conventional sources (among which nuclear has mixed characteristics) have historically been:
- Contaminants: Especially fossil fuels, although nuclear power emits very little CO2 during operation.
- Limited: By depending on finite raw materials (uranium, gas, coal, oil).
- Dependents from abroad: Especially in the case of Spain, which imports almost all of its uranium for nuclear power.
- Producers of hazardous waste: In the nuclear case, radioactive waste that requires management for thousands of years.
What makes nuclear energy different?
Nuclear energy is generated from the fission (and in the future, fusion) of atomic nuclei of elements such as uranium and plutonium. Its main advantage is the ability to produce large amounts of electricity continuously , without depending on weather conditions and without emitting CO2 during its generation cycle.
Nuclear power plants have a high energy density . This means that, with a relatively small amount of fuel, they can generate enormous amounts of electricity . Furthermore, their operation is constant (except for maintenance shutdowns), which provides stability to the electrical grid.
However, nuclear power faces considerable challenges, such as radioactive waste management, the high cost of construction and decommissioning, and the potential risk of serious accidents (historical cases like Chernobyl and Fukushima remain in the collective memory and are reflected in international regulations). For more information on these aspects, you can consult the environmental impact of nuclear energy.
Cost comparison: Who is more competitive today?
One of the most relevant aspects for investors, governments, and citizens is the levelized cost of energy (LCOE). This indicator measures the total cost of building and operating a power plant divided by all the electricity it will generate over its lifetime. It allows for a fair comparison of different technologies.
According to data from the World Nuclear Industry Status Report (WNISR) and the World Nuclear Association (WNA), the levelized costs of solar energy have fallen by 90% in the last decade, and those of wind energy by 72% . Nuclear energy, on the other hand, has only reduced its cost by 36% since 2009 and, in some cases, has even increased due to stringent safety requirements and project complexity. For a more in-depth analysis, you can visit the benefits and risks of nuclear energy page.
- Solar energy: $36 per megawatt hour (MWh).
- Wind power: $38 per MWh.
- Nuclear energy: $67 per MWh (almost double that of major renewables).
Renewables have a clear advantage, as their costs continue to fall steadily , while nuclear power requires high initial investments and long construction times (on average, 7 to 9 years).
Construction time and return on investment
Renewable energy facilities can be built much faster than a nuclear power plant. For example, a wind or solar farm can be operational in a matter of months or a couple of years, while a nuclear plant requires between 7 and 9 years to build (in some cases, longer). To better understand how these facilities work, we recommend reading about how a nuclear power plant operates.
During this period, the invested capital remains "idle," representing a significant opportunity cost. Furthermore, regulatory and technological uncertainty can further increase the cost of commissioning new nuclear power plants , while renewables typically benefit from regulations that incentivize their deployment.
Generation capacity, availability and efficiency
One of the most frequently cited arguments in favor of nuclear power is its ability to provide a constant supply of electricity, regardless of the weather or time of day . Renewable energy sources, on the other hand, depend on wind power, solar radiation, or river flow, making their production more variable. To learn more about how a nuclear power plant works, you can visit [website address missing].
However, recent data shows that installed capacity and annual renewable energy production already surpass nuclear power in numerous countries . For example, solar power has a global capacity of between 848 and 942 GW, while wind power is around 823,5 GW (2021 data). In terms of annual production, wind power generates 1850 TWh and solar power 1032 TWh each year, making wind power the world leader in renewable electricity production.
In Spain, the trend is even more pronounced , with wind and hydropower almost doubling the contribution of nuclear power in some months, according to 2024 data.
Investment Analysis: How Much Do the Same Euros Invested Yield?
Comparative studies, such as that conducted by the Department of Electrical Engineering at the Polytechnic University of Valencia, offer a revealing perspective. For every €4.000 billion invested, a 1 GW nuclear power plant can generate approximately 7.423 GWh annually. The same amount invested in wind energy (where the cost per GW installed is €600 million) allows for the installation of 6,666 GW, which, even operating 2.000 hours per year, produce 13.333 GWh annually (179% more energy). To better understand the investment potential in renewables, see .
In the case of photovoltaic solar power, which currently costs around €1.200 billion per GW installed, the same €4.000 billion could fund a 3,333 GW plant capable of generating approximately 5.333 GWh annually in an average location like Alicante. In regions with higher solar radiation, this figure increases significantly. Furthermore, the maintenance and fuel costs of solar plants are almost negligible compared to nuclear power.
This analysis demonstrates that investment in wind and solar power is significantly more efficient from an economic and energy perspective , without taking into account the waste management problems and risks associated with nuclear power.
Advantages and disadvantages of nuclear energy compared to renewable energy
Main advantages of nuclear energy
- High energy density: It can generate huge amounts of electricity in a small physical space, ideal for countries with territorial limitations.
- Constant electricity: Its production is independent of weather conditions, ensuring a stable and predictable supply.
- Low GHG emissions: Virtually zero during operation, key in decarbonization scenarios.
- Conversion efficiency: High efficiency in the transformation of fuel into electricity.
Key disadvantages of nuclear power
- Radioactive waste management: It generates hazardous waste that must be stored safely for thousands of years, with technological and social uncertainty. For more details, see Nuclear radiation.
- High initial and maintenance costs: Construction, operation, and decommissioning involve high outlays and long payback periods.
- Risk of serious accidents: Although the probability of accidents is low, they have disastrous consequences, as demonstrated by the historical cases of Chernobyl and Fukushima.
- Dependence on imported materials: Spain, for example, imports most of the uranium needed for its power plants.
- Proliferation problems: Nuclear technology and materials can be diverted for military purposes, adding to the geopolitical concern.
Advantages of renewables over nuclear energy
- Decreasing cost and greater competitiveness: Solar and wind power have massively reduced their costs and are now more profitable than nuclear power for new plants.
- Lower environmental and social impact: They do not generate hazardous waste or risk of major accidents.
- Ease and speed of deployment: They allow for increasing installed capacity in short periods of time.
- Autonomy and less external dependence: Spain, for example, can exploit its natural resources (sun and wind) without depending on imports.
The role of hydraulics and the integration of renewables
Hydropower, although its growth is limited by the availability of water resources, remains fundamental to the Spanish electricity system as it allows for the storage of large amounts of energy and the regulation of the grid. In particularly rainy months, its contribution can exceed 17% of total production, as happened in January 2024.
Renewable energy as a whole, thanks to the complementarity of different technologies and advances in storage solutions (batteries, pumped hydro), are increasingly capable of guaranteeing stable and sustainable coverage for electricity demand.
Critical points and future challenges
Despite the growth of renewables, challenges remain: the variability of solar and wind power requires advanced backup, interconnection, and storage systems. The modernization of the electricity grid and regulatory reforms are accompanying this process.
Nuclear energy, meanwhile, faces public pressure, rising costs, and the climate emergency that demands rapid and scalable solutions to decarbonize the economy. Although some experts defend its usefulness as part of the energy mix in the transition, the global trend points toward an accelerated expansion of renewables, mainly due to their decreasing cost and their ability to reduce dependence on imported and polluting sources. For more information on nuclear energy, see [link to relevant information].
Technological advances, falling costs, and the increased integration of renewable energy mean that, in practical terms, the future of the global electricity system clearly points toward more sustainable, efficient, and indigenous solutions, leaving behind the dependence on technologies with higher risks and costs.
