Will Fusion Replace Solar?

Will fusion replace solar?

Fusion and solar power are two technologies currently being developed as sources of clean, renewable energy. Fusion involves combining light atomic nuclei to form heavier nuclei, releasing massive amounts of energy in the process. The most promising approach to fusion energy uses magnetic fields to contain hot plasma inside a tokamak reactor. Solar power, on the other hand, converts energy from sunlight into electricity using photovoltaic cells or concentrated solar thermal plants.

Tokamak reactors able to produce net energy gain have not yet been developed, but major advances in plasma physics give optimism that fusion can become a practical power source this century. Meanwhile, solar power capacity is growing rapidly around the world and accounted for over 3% of global electricity in 2018. Solar panels have become very cost-competitive in recent years. While solar and fusion hold great promise as carbon-free energy solutions, there is debate whether they will complement or compete with each other in the future.

This article examines the current status and future outlook for fusion and solar power. It analyzes their respective advantages, costs, and timescales for adoption. The key question explored is whether fusion will ultimately displace solar energy or if the two technologies will co-exist in a renewable energy mix.

Current State of Fusion vs Solar

Fusion power has yet to be harnessed for commercial energy production, while solar power is a growing source of renewable energy worldwide. The leading fusion energy project is the International Thermonuclear Experimental Reactor (ITER), currently under construction in France with an expected completion date of 2025. ITER aims to produce a ten-fold return on energy, demonstrating the feasibility of fusion power on a commercial scale. However, significant technical challenges remain in containing the fusion reaction and generating more energy than is put into the system.

In contrast, solar photovoltaics is a mature industry that has experienced rapid growth and cost reductions in recent decades. Total global solar PV capacity reached over 580 gigawatts in 2019 and is projected to grow substantially in the coming years. While solar only accounted for about 3% of global electricity in 2018, it is one of the fastest growing renewable energy sources worldwide. Key factors enabling this growth are improved efficiency, reduced manufacturing costs, and supportive government policies.


Challenges Facing Fusion

Fusion power faces significant technical challenges before it can become a viable large-scale energy source. Controlling the fusion reaction and sustaining it for long durations remains difficult. According to General Atomics, one key challenge is developing magnetic confinement systems that can withstand the immense heat and pressure inside fusion reactors (source). The high-energy neutron flux inside reactors also damages internal components.

Funding has been another major constraint, as fusion research requires massive capital investments. The ITER experimental fusion reactor being built in France, for instance, has faced huge cost overruns totaling over $20 billion. Its completion date has been pushed back to 2025 at the earliest (source). Insufficient funding has slowed progress.

Timescales remain a big question mark, with practical fusion energy potentially 40-50 years away. The challenges of plasma physics and engineering mean fusion reactors likely won’t contribute substantial electricity to grids until at least 2050 (source). While research is accelerating, fusion still remains a long-term prospect.

Growth of Solar Power

In recent years, the growth of solar power capacity has accelerated rapidly thanks to declining costs and increased adoption worldwide. According to https://www.savingwithsolar.com.au/worldwide-solar-power-growth-2017/, solar power was the number one source of new power generation capacity in 2016. Total global solar capacity reached 303GW in 2016, representing a growth rate of 50% from 2015. Similarly, https://www.savingwithsolar.com.au/category/solar-power-in-china/ reports that China alone installed over 34 gigawatts of new solar capacity in 2016.

The massive growth in solar is largely driven by rapidly declining costs. Between 2010 and 2016, the average global cost of solar panels dropped by over 70%. This dramatic price decrease has made solar power cost competitive with fossil fuels in many parts of the world. As costs continue to fall, adoption of solar energy is expected to accelerate. Solar’s share of global electricity generation is projected to grow from 2.2% in 2016 to 4.2% by 2021, according to the International Energy Agency.

Advantages of Fusion

Fusion power has several notable advantages that make it an attractive potential energy source for the future. First, the fuel for fusion is abundant and widespread. Fusion reactions use isotopes of hydrogen such as deuterium and tritium which can be readily extracted from seawater (https://ccfe.ukaea.uk/fusion-energy/fusion-in-brief/). There are enough reserves of these light elements to power civilization for millions of years.

Second, fusion power would produce little to no greenhouse gas emissions or air pollution. The reaction creates no carbon dioxide. Fusion would complement renewable energy sources like solar and wind in providing clean electricity to combat climate change (https://www.europarl.europa.eu/RegData/etudes/ATAG/2023/747449/EPRS_ATA(2023)747449_EN.pdf).

Finally, fusion reactions release prodigious amounts of energy from a small amount of fuel. Each kilogram of fuel produces energy equivalent to around 10 million kilograms of fossil fuel. The high energy density of fusion promises a concentrated power source able to meet the world’s growing energy demands.

Disadvantages of Fusion

Despite the potential of fusion power, there are some key drawbacks and limitations that need to be considered. Firstly, fusion reactors remain unproven at scale (Source). While experimental and demonstration reactors exist, no full-scale commercial fusion reactor has ever been built. Scaling up the technology comes with engineering challenges. Until large fusion plants are actually constructed, the feasibility of scale remains theoretical.

Secondly, fusion reactors require very high upfront capital costs (Source). Building the first commercial fusion plants will likely cost tens of billions of dollars due to the sophisticated materials, complex engineering, and precision required. While costs may fall with scale, fusion is unlikely to be cheap anytime soon. The massive investment required could limit adoption.

Comparative Costs

Currently, fusion energy is still in the research and development phase, with no commercial fusion reactors yet in operation. In contrast, solar power is a mature technology that has seen rapid declines in costs in recent years. According to the International Renewable Energy Agency, utility-scale solar PV power costs have fallen 82% between 2010 and 2019, making solar one of the cheapest sources of electricity in many parts of the world.

Most experts estimate that fusion energy will be significantly more expensive than solar power if and when commercial fusion reactors come online, at least initially. According to an analysis by the EUROfusion Consortium, fusion electricity in 2050 could cost €60-€82 per megawatt hour, compared to €46-€64 per MWh for onshore wind and €48-€70 per MWh for solar PV. However, there are hopes that fusion costs could fall dramatically in the long run after the technology matures, perhaps reaching parity with renewables. Elon Musk has argued fusion may not become cheaper than wind and solar.

Overall, it appears clear that fusion will start out at a significant cost disadvantage versus solar power and other renewable energy sources. But the potential for fusion to one day become a low-cost baseload power source means it could play a complementary role to intermittent renewables like solar in a future carbon-free grid, if the remaining scientific and engineering challenges can be overcome.

Timescales for Adoption

Mainstream adoption of fusion power is still likely decades away. The ITER experimental fusion reactor being built in France, backed by China, the EU, India, Japan, Korea, Russia and the US, is not expected to generate net energy gain until the 2030s. The EU roadmap aims for a first-of-a-kind fusion power demonstration plant in the 2050s. According to analysis by the Royal Society, fusion could supply a few percent of global electricity by 2050 and expand to around 50% of generation by 2100 in an optimistic scenario.

Private fusion companies like Commonwealth Fusion Systems and TAE Technologies have set more ambitious timelines, targeting net energy production by the 2030s. However, beyond demonstrating the physics, there are still non-trivial engineering challenges around turning prototypes into economical commercial power plants and scaling up rapidly. Realistically, it may take until at least the second half of the century for fusion to become a major contributor to the global energy mix.

In summary, fusion holds enormous long-term potential but is unlikely to completely replace other low-carbon technologies like solar and wind at scale before 2050. Fusion can eventually complement renewables once commercialized, but not fully replace them in the near future.

Fusion as a Complement or Competitor

There is debate about whether fusion and solar power can coexist in the future or if fusion will completely replace solar power. Some key considerations:

Fusion may not fully replace solar due to challenges scaling up quickly. According to Scientific American, fusion is not likely to arrive quickly enough to address near-term climate change targets, but could play a role long-term. This suggests fusion may complement rather than replace solar in the next few decades.

However, if fusion is eventually perfected, some experts argue its potential abundance could make solar obsolete. Fusion offers theoretically limitless energy production without sunlight dependency or nighttime drops in power. But cost-competitiveness with solar is unclear.

Ultimately the two technologies may play complementary roles, with fusion addressing long-term base load needs and solar providing distributed renewable energy. Rather than a winner-take-all scenario, experts argue a mix of energy sources will be needed. But the future balance between solar and fusion remains to be seen.


In summary, fusion power shows great promise as a clean, safe, and virtually limitless energy source for the future. However, significant scientific and engineering hurdles remain before fusion can become commercially viable and widely adopted. Meanwhile, solar power continues to grow rapidly thanks to falling costs and proven technology. Rather than competing, fusion and solar may end up complementing each other in a future clean energy mix. Fusion could provide steady baseline power, while solar meets peak demand and supports grid flexibility. But any widespread use of fusion likely remains multiple decades away. While the long-term theoretical potential of fusion is enormous, solar power is growing rapidly today. Ultimately, pursuing both fusion and solar research makes sense to build a robust and sustainable clean energy system. With continued progress, fusion may one day displace fossil fuels, but solar will pave the way to get us there.

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