Comparing The Advantages and Disadvantages of Fusion Versus Solar Plus Battery Storage

Our article last week contrasted nuclear fission energy versus fusion energy, especially on how they are similar and how they differed. Which inspired us to look at fusion energy vs. solar energy augmented by energy storage batteries. From most forecasts, solar energy was the fastest-growing energy source between now and 2050 (at least before the Trump Administration #2), growing from 7.6% of worldwide electricity production in 2025 to 20.1% in 2050. In the US and Canada, solar was forecasted to grow from 9.5% of electricity generation in 2025 to 28.1% in 2050.

What Makes Solar So Attractive?

There are several reasons that photovoltaic (PV) solar electricity generation is attractive as a source of electricity:

• Solar is one of the fastest electricity sources to deploy. On average, it takes 8-18 months to plan, permit, build, and commission a solar energy farm. This is similar to that for a 1GW natural gas electric power plant, and is considerably less than the timeline for nuclear fission power plants which tend to be between 5 and 20 years.

• Solar electricity is reasonably cheap to build. The average construction cost for a 1GW solar electricity installation in 2022 was $1.56 billion according to the US Energy Information Agency (US-EIA). While nearly 70% more expensive than a natural gas power plant of the same size, it is about 22% less than a coal electricity power plant, and less than a quarter of the cost of a nuclear fission power plant.

• Solar electricity operating expenses are the lowest of all energy sources. Unsurprisingly, the average total operating expense (in US $ per kilowatt-hour) is lower than any other fuel source of electricity. This is primarily driven by solar’s zero fuel cost, amplified by the “lights-out” operation of solar electricity farms. In general, the only long-term maintenance costs are inverter failures.

• Solar electricity is non-polluting (during operation). Solar electricity generation by itself produces no pollution, though the building of solar panels does have some environmental impacts.

With all of the above said, the greatest drawback of solar electricity generation is that it is non- dispatchable, i.e. it cannot be arbitrarily turned on and off. Unsurprisingly, solar only works when the sun is shining, meaning that during half the day solar panels are not producing electricity. The typical approach is to augment solar energy farms with battery-based energy storage (typically lithium-ion batteries). This significantly increases the initial deployment costs of a solar energy farm. Moreover, the production of lithium-ion batteries has significant environmental impacts, and recent battery fires at solar energy farms have caused considerable public concerns and outright opposition to their deployment in both New York and California, both of which have had significant battery fires.

The final issues that are generally cited by solar energy critics have to do with the amount of land required, and the need to build new transmission lines to those plants. A 1GW solar farm requires between 4,000 and 6,000 acres of land (roughly 6.5 to 9.4 square miles) to hold all of the panels required. Note that in most cases, these plants need to be “overbuilt” (i.e., to generate more than 1 GW during operation) so that there is power to charge the batteries to supply power at night (which also increases initial construction expenses of solar electricity farms). Given the size of these solar farms, they almost always have to be built outside of urban areas, requiring new transmission lines to be run to them.

How Does Fusion Electricity Generation Compare to Solar Electricity?

It is ironic in a way how similar (and how different) fusion energy and solar energy are. Solar energy is created by the fusion of hydrogen in the sun, using a similar (but not same) process as earth-bound fusion does. Both are the “energy of the future”, holding the most promise to generate the amounts of energy required by our planet in this century. Both are also powered by the most abundant element in the universe – hydrogen, though earth-bound fusion can also be powered by proton-boron fuel, and interstellar fusion can use heavier elements such as helium, carbon, and even silicon.

As similar as solar energy and fusion energy are, the differences between them are incredibly stark. Besides dispatchability, one of the biggest differences is energy production density. In this attribute, solar is extremely low, while fusion should be similar (though somewhat less dense) to that of a nuclear fission plant or a fossil fuel plant. The similarity in density between fusion energy and existing power generation sources such as fossil fuels or nuclear fission enables fusion to fit into the footprint of existing power plants. This simplifies brownfield deployments of fusion energy, while solar energy is limited to greenfield opportunities.

Finally, solar energy is an “end-of-the-road” technology. While we can expect efficiency improvements in solar, the limit for single-junction cells is 33%, while multi-junction cells may reach up to 47%. Current commercial panels have efficiencies of 12%-21%, meaning that the best-case improvements would be 2X-4X. Alternative uses for solar are also extremely limited; it is single-purposed. Fusion on the other hand is at the start of its maturity cycle, and improvements in fusion performance over the next several decades are highly likely. Fusion technology also has a lot of alternative uses besides energy generation, such as the creation of high-energy neutrons, and the generation of tritium. These capabilities mean that investments in fusion can result in multiple positive outcomes.

Fusion and Solar Energy, While Different, Are Complimentary

The increase in energy consumption on Earth is only going to accelerate in the next several decades. If anything, the US-EIA forecast of a 50% increase in worldwide electricity consumption is highly conservative. Factors driving increased electricity consumption include:

• The rapid expansion of datacenters, particularly AI datacenters.
• The electrification of industrial and commercial processes.
• The electrification of residential heating and cooling.
• The electrification of transportation, particularly motor vehicles, but also rail-based transportation and eventually air and sea transportation.
• The exponential increase in robotic technologies and solutions as more of these processes become automated.

If all of this comes to pass, the increase in electricity demand will likely exceed 2X by 2050, and possibly approach 2.5X. We will be in a situation where we will likely need more than one solution to increasing the generation of electricity. Fusion, solar, wind, and even fission will all have a place in providing the solution to our power needs in the next decades.