Publications

- June 1, 2021: Vol. 8, Number 6

Renewable energy — beyond sun and wind

by Sheila Hopkins

Although there is still a vocal contingent of people who view renewable power sources as unworkable, the truth is that renewable power generation has gone mainstream. In 2020, about 20 percent of the energy generated in the United States came from sustainable sources, according to U.S Energy Information Administration (EIA). And this percentage will only grow as the states with formal renewable power targets, some of which are aiming for 100 percent renewable energy generation by 2050, move toward achieving those targets.

The growth in the percentage of energy produced by renewables has certainly been helped by government initiatives — such as federal decarbonization standards, the Paris Treaty and net-zero goals — but much of the increase in use is due to renewables now being less expensive than carbon-based sources. In many cases, it’s simply more economical to produce energy via renewables than carbon-based fuels. For example, in its most-recent reports, Levelized Cost of Energy and Levelized Cost of Storage, investment bank Lazard found that an average MWh of utility-generated solar power was $36, while onshore wind power came in at $40 per MWh. In comparison, MWhs of natural gas from a combined-cycle plant averaged $59, and coal had risen to $112.

Although renewables have made great strides in the past few years, there is still lots of room for improvement. Current research can be divided into two parts: incremental advances in today’s technology, which can have outsized effects; and transformational advances, which might be a decade or more away from making an impact — but are needed to realistically move to 100 percent sustainable-generated energy.

SOLAR AND WIND, OUR OLD FRIENDS

When you mention renewables, most people immediately think of solar- and wind-generated energy. And rightly so. These two sources together make up about one-third of all sustainable energy generation, according to the EIA, and have been the focus of most of federal tax credits and support. As such, even incremental advances in their technology can play a large role in improving their impact.

“There are a lot of aspirational ideas to achieve a low carbon in the future,” says Nick Cleary, a partner at Vantage Infrastructure. “Unfortunately, much of that aspiration is hard to convert into action today because of the high cost or unproven technology. But when you look past the hype, there’s already a lot that is being done to accelerate renewables use and decarbonization using proven technologies with competitive costs.

“What I see as the really exciting opportunity and challenge is the integration of energy transition across previously separate markets, like the cross‐over between real estate and solar,” Cleary continues. “We already have residential solar that delivers consumers with lower cost electricity than utilities, where the panels are part of the roof, and with a battery in the garage it integrates a home with the electricity grid and recharges your car. It’s only an incremental step for building materials, such as roof tiles or skyscraper cladding, to be embedded with traditional solar cells and smart technology that can accelerate this integration of markets and our ability to achieve a net-zero economy.”

Embedding solar panels in building materials is just a start. Solar technology is the focus of some of the more promising research, which often looks at how to make solar-gathering materials more efficient. One of the incremental advances that is already increasing efficiency is the two-sided panel. When installed on a light-colored roof or pavement, these panels can absorb energy directly from the sun, as well as indirectly from the mounting surface. It is estimated they are 30 percent more efficient than the standard panel.

Looking further into the future, several companies are working to develop systems that would allow conventional PV panels to be installed on large bodies of water, such as lakes and reservoirs. These large-scale floating solar farms would be helpful in areas lacking large, open land masses, and could open the world of solar collection to areas where land is being used for a higher purpose — housing, agriculture or industry — but open waters are readily available.

Advances in wind technology have primarily been focused on reducing costs, improving efficiency and making maintenance easier. For example, engineers have found that simply changing the shape of the blades can improve efficiency. Conventional blades bend upwards, but if you bend the blades down, they can be made out of lighter, more flexible materials plus will hold more wind at lower speeds. These improvements could move turbines out of the middle of nowhere and into the middle of civilization, where the energy is actually needed.

“Continued improvements in technology are allowing wind turbines to produce much more energy at low-wind sites,” says Chris Taylor, data center energy lead at Google. “These lower wind sites are more common close to where people live and energy loads are centered.”

One of the challenges facing wind turbines is the cost of maintenance. Towers are tall. It’s hard for observers to catch damage before it becomes critical. To solve this problem, engineers are working on developing autonomous, roving robots that can attach to a wind turbine and detect any problems. Locating turbine damage early can minimize maintenance costs and turbine downtime, which can improve their lifespan and efficiency.

Solar and wind along with other standbys, such as hydro and biomass, are all playing a part in the energy transformation, but to reach net zero by 2050, we are going to need to see some truly transformational advances. So, where do we stand on renewables of the future?

HYDROGEN, OUR ROCKSTAR FRIEND

The promise of hydrogen is high on everyone’s list of future sustainable energy. In fact, it is seen as something of a magic bullet by many looking to move the country to net zero.

“There is no pathway to net zero that does not include hydrogen and fuel-cell technologies at its core,” asserts Daniel Brock, co-leader of H2EAT.

That is likely a true statement, yet the problem with putting so much faith into hydrogen is that hydrogen has problems. Hydrogen is the most abundant element in the universe, though it is not found on its own in nature. So, the trick is separating it from its companion elements. Although there are many ways of producing pure hydrogen, one of the easiest is to just run electrical current through water. The current separates the molecules into hydrogen and oxygen. The hydrogen can be stored as a gas or liquid, which can then be used as a clean transportation fuel or to generate electricity that can be transported or stored. It is considered “green hydrogen” if the energy used to separate the molecules comes from a sustainable source, such as wind or solar.

“The technology has existed for years and is proven,” says Taylor. “Now that the costs are coming down, it’s an interesting idea for solving both the transportation fuel issue — without using food for fuel — and potentially energy storage, as well. I think you’ll be hearing about it a lot in the near future.”

The advantages of hydrogen are well known. Supply is virtually limitless. It can be used where it is produced or transported elsewhere. It can be produced from excess renewable energy and stored in large amounts for a long time. Pound for pound, hydrogen contains almost three times as much energy as fossil fuels, so less of it is needed to do any work. And a particular advantage of green hydrogen is that it can be produced wherever there is water and electricity.

Hydrogen can also be used with fuel cells to power anything that uses electricity, such as electric cars, or tied into a power grid. Because of its energy efficiency, a hydrogen fuel cell is two to three times more efficient than an internal combustion engine fueled by gas. And a fuel cell electric vehicle’s refueling time averages less than four minutes.

Despite its benefits, hydrogen is not without its challenges (if there were no challenges, we would all just start using hydrogen for energy and be done with it). Hydrogen is extremely flammable and is prone to exploding if not handled correctly. (Remember the Hindenburg?)

Because hydrogen atoms are so light, they tend to leak through pipelines. To prevent a rash of escaping atoms, they need to be supercooled to form a liquid, or compressed to 700 times atmospheric pressure to be delivered as a compressed gas. The super cold liquid and super compressed gas would damage existing pipelines, so currently, hydrogen is transported through dedicated pipelines (which we don’t have many of) or in tankers. However, hydrogen can be mixed with natural gas and delivered through existing infrastructure, though you then lose some of the “green” benefits you are aiming for.

A McKinsey study, Road Map to a US Hydrogen Economy, estimated that by 2030, the U.S. hydrogen economy could generate $140 billion and support 700,000 jobs. However, at the moment we don’t have the pipeline or transmission infrastructure for this growth. Ultimately, whether or not green hydrogen fulfills its promise and potential depends on how much carmakers, fueling station developers, energy companies, governments and other capital providers are willing to invest in it over the next decade or two.

NANOTECHNOLOGY, NEW KID ON THE BLOCK

Nanotechnology is miniaturizing the universe, and this includes renewable energy. One nanometer is 1 billionth of a meter or 1 millionth of a millimeter. To get an idea of scale, if a marble represented one nanometer, then the earth would represent one meter. So, a marble compared to the size of the planet.

In the renewable world, nanotechnology research is looking to miniaturize solar-gathering panels. And by miniaturize, we mean make the solar-collectors microscopic. We aren’t far off in making this a reality. David Weber, a University of Southern California researcher,  has developed a solar-collecting paint by using solar-collecting nanocrystals floating in a liquid solution. If commercialized, this solution could be used to paint a house, a car, an office building — anything and everything could be turned into a solar-collecting panel. So, why isn’t this available in the market yet? Well, those nanocrystals were built with cadmium, which is a highly toxic metal. No one want to wear hazmat suits inside their house.

However, because the idea is so intriguing, researchers have been busy trying to find alternative materials. Quantum dots, for example, might be one answer.

Quantum dots are sometimes referred to as artificial atoms because they share many of the same properties. In June 2020, researchers at the Los Alamos National Lab were able to create cadmium-free quantum-dots solar cells. They had many of the same advantages as the original solar-collecting paint, plus you didn’t risk your life using them.

Going down a different path, researchers at the University of Sheffield in England were able to develop a spray-on solar film using perovskite. It consists of a 300-nanometer thin film that aids solar absorption and can operate efficiently even on cloudy days. Researchers believe it could be printed using an inkjet printer, which would open the flood gates for where you can apply solar power (assuming you haven’t run out of an ink cartridge and the printer refuses to print until it is replaced).

Another group has been working on turning bricks into super capacitors. Washington University’s Institute of Material Science and Engineering has found that by applying their iron oxide (i.e., rust) polymer process to a standard red brick (the red comes from rust), you end up with a solar capacitor. They estimate that it would take about 50 bricks to power an emergency lighting system for five hours.

NUCLEAR, THE FRIEND WHO NEVER LEFT

Nuclear power has gotten a bad rap over the years, yet researchers are claiming the future could be a nuclear one. Nuclear is not considered a renewable power source, but in a drive to net zero, a clean energy source that is carbon-free and available 24 hours a day is attractive. However, nuclear is hindered in its development by two huge hurdles: cost and time to build, and fear of meltdowns that make the surrounding area unlivable for many generations to come.

“We really need carbon-free sources of energy,” says Chris Levesque, president and CEO of TerraPower. “Nuclear is an elegant solution. There are things that are being done now that should have been done 20 years ago.”

Those things that should have been done include attacking the hurdles that have kept nuclear on the outside of the “in” group.

One of the ways researchers are attacking the cost-and-time-to-build problem is through mini-reactors. These small, modular reactors aim to be put in place within 500 days, which is a lot more attractive than the 10-year timeframe for the standard models.

To prevent meltdowns, new systems are using materials that simply cool down rather than melt down if things go wrong. For example, X-energy is working on a system that uses helium gas instead of water to transfer heat from nuclear fission to boiling water. A natrium reactor, on the other hand, uses molten sodium metal to heat up salt to boil water and run a turbine. Neither of these reactors can meltdown, so the specter of another Three Mile Island would be moot.

While this next generation of reactors could possibly bring additional nuclear plants online in the next 10 years, they are only seen as a stop-gap solution while we wait for the holy grail of fusion power.

Fission is what we have now. In layman’s terms, it is the splitting of the atom. Fusion, on the other hand, is when two atoms slam together to form a single, heavier atom. Energy is released from both actions, but the benefits of fusion make it far and away the top choice for producing nuclear energy.

One big benefit of fusion over fission is that it doesn’t produce highly radioactive products, so the problem of what to do with radioactive waste is solved. In addition, its meltdowns are rather mild. If a fusion reaction becomes unstable or imbalanced, it naturally slows down, dropping the temperature until it stops. The worst-case scenario is damage to the fusion reactor and the immediate surroundings, but very little else.

Finally, fusion fuel can be extracted from elements found in sea water, so there’s enough fusion fuel on earth to power the planet for millions of years. So, why aren’t we filling the world with fusion nuclear plants? Well, we haven’t been able to produce a fusion reaction in an energy-efficient and sustained way yet. It takes more energy to generate the heat and pressure needed to create the fusion reaction than the energy produced. That sort of defeats the purpose of the whole exercise.

But scientists are hopeful that particular problem can be solved. The benefits are just too great to give up. In fact, the benefits of working toward advancements in all areas of sustainable and clean energy are too great to give up. Net zero, here we come.

 

Sheila Hopkins is a freelance writer in Auburn, Ala.

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