Open Problems: Key Remaining Challenges in Clean Energy Research

Problem 1: Large-scale storage to enable solar and wind growth

What the world needs to solve this problem:

Description

To deploy variable energy sources like solar and wind on a large scale, we need to store energy from when it is generated until it is needed for use. There are many different storage technologies out there, from various batteries to thermal storage, compressed air, and pumped hydro. Reducing the cost, and increasing efficiency and scalability of these systems is crucial to the success of renewables. These technologies need to get a lot cheaper and more efficient to enable large-scale deployment of solar and wind.

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Problem 2: Better, more sustainable, and (even) cheaper batteries for cars and trucks

What the world needs to solve this problem:

Description

As electric vehicles become more popular and electrification starts to accelerate, work on batteries becomes more and more urgent. We want batteries to have longer lifetimes, become even simpler and cheaper to manufacture, and have better performance. Work to make well-performing batteries with less or no cobalt is vital too. This is because cobalt is both unsustainable and expensive when demanded in large quantities.

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Problem 3: Hydrogen from electricity: cheap and efficiently

What the world needs to solve this problem:

Description

Hydrogen could replace carbon-based fuels in airplanes and ships, and could maybe compete with batteries in cars…if only we could make it efficiently. The cost of renewable electricity is only part of the equation here. Electrolyzers, the machines that make hydrogen from water, need to become cheaper. Because hydrogen is a gas at room temperature, it needs to be compressed. The compression process, therefore, also needs to be optimized and potentially integrated directly with electrolysis.

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Problem 4: Make nuclear cheaper and build reactors faster

What the world needs to solve this problem:

Description

The median construction time in 2018 was eight-and-a-half years. This naturally increases the financial and political risk of building new reactors. The cheaper and faster reactors are, the higher the incentive to build new ones.

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Problem 5: Make nuclear popular & encourage pro-nuclear-research policies and funding, especially in growing economies

What the world needs to solve this problem:

Description

Nuclear energy is an incredibly safe and low-carbon source of energy. Nuclear power has some opposition due to rare, but highly visible, accidents. Facing a challenge as bad as climate change, it’s worth carefully weighing up our options. We don’t want to make up our mind irrationally and miss out on something great!

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Problem 6: Recycle nuclear waste in breeder reactors

What the world needs to solve this problem:

Description

Nuclear waste could, in theory, be reused as fuel for a different type of reactor called a “breeder” reactor. This would be great for a few reasons: cost, fuel availability, and of course because there would be less waste. However, this technology is unproven to date and requires more work to become a reality.

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Problem 7: Earth-abundant thin-film solar: cheaper & sustainable?

What the world needs to solve this problem:

Description

Thin-film solar panels are a type of Solar Photovoltaic technology. Today’s commercial thin-film solar cells are made from scarce elements, meaning we can’t build a lot of them. Recent work on them aims to use materials that are much more abundant on Earth. Ultimately, these cells could be lower-cost, more sustainable, and more efficient than today’s commercial silicon or thin-film technologies.

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Problem 8: Recycling of solar panels

What the world needs to solve this problem:

Description

The resources our planet offers us are limited, and some of those used for Solar PV are especially rare. Solar panels have useful lifetimes of around 25 years. After that, we would have to replace them with new panels. This creates two problems: 1) the old panels are now waste, and 2) constructing the new panels will require raw materials. The sad reality is that, today, most e-waste from developed nations is being irresponsibly exported to, and dumped in, developing nations. Being able to affordably recycle materials from old panels and make new panels from them could solve these problems.

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Problem 9: Floating turbines

What the world needs to solve this problem:

Description

Today’s offshore wind turbines can only be built near to the coast. Unfortunately, the winds near the coast are slower and less constant than in the deep ocean. Floating wind turbines could be anchored to the seabed with long steel cables, allowing them to be placed in much deeper waters. There, winds are stronger and more consistent. Several trials of this technology are underway around the globe.

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Problem 10: Artificial Photosynthesis

What the world needs to solve this problem:

Description

What if we could do what plants do to make energy, but do it better? Researchers are working on technologies that directly turn water, sunlight, and air into H₂ and O₂, or even fuels similar to those we use in cars today. This could allow us to use the liquid fuels our society has grown used to, but produce them sustainably.

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Problem 11: Cheaper Hydrogen from Electrolysis

What the world needs to solve this problem:

Description

Cheaper electrolyzers and more efficient hydrogen compression technologies could enable hydrogen to become a popular and versatile energy storage medium.

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Problem 12: Make Tokamak Fusion Work

What the world needs to solve this problem:

Description

There are many open problems in tokamak fusion reactors. That they currently take more energy to run than they produce is only one and potentially the one we have come closest to solving. Making Tritium from Deuterium, Lithium-6, and neutrons coming from the fusion reactions is difficult and requires more research. Protecting the reactor during operation is another issue. Solutions to these problems need to be combined with a system to get the energy out of fast-moving neutrons.

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Problem 13: Make other fusion methods work

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Description

There are many ideas in fusion science; not only tokamaks. While many of them are unlikely to be successful in the near- or mid-term future, or maybe ever, it’s still an option to explore them. We list some below.

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