Based on papers published at the same time by unrelated teams, two methods for improving capacitors’ ability to store charge appear to be effective. Each has the potential to make supercapacitors better at storing energy and maybe even put them in the running for large-scale energy storage.

For a long time, supercapacitors have been better than batteries because they can quickly release the charge they have stored. But not even the best supercapacitors have been able to store enough power to meet the most important needs of society. Sometimes, big steps forward have made supercapacitors look like they could compete in that market. But since lithium-ion battery prices have dropped so much, there isn’t much room for other batteries. That could change soon.

Two papers that came out last month in the same issue of Science both look at big improvements in capacitance. It remains to be seen if either of them can be scaled up, though.

The basic idea behind all capacitors is the same. There is material between the positive and negative charges to keep them from jumping across the gap. When a switch is closed, the negative charges can move around to meet the positive charges. This makes an electric current, which can be used for many things.

Laptops and phones now have hundreds of capacitors inside them. When you look at a phone, you can tell how small it is. Because of this, the amount of power they can store is many times too small to power a car, let alone a city all night.

As you might guess from their name, supercapacitors have a lot more capacitance. Even though they’ve made regenerative braking possible, batteries are still the best choice for long-distance driving. To make that happen, the capacitance has to go up, which means finding cheap materials that stop very large amounts of charge from recombining.

Many capacitors use ferroelectric materials like BaTiO3, but they have a problem called “remnant polarization,” which means that some charge stays behind instead of being released. Their crystals also break down over time.

A team from Korean and American institutions reduced remnant polarization by putting a 3D structure between 2D crystals. They were then able to store 191.7 joules per cubic centimeter of capacitor and release it with more than 90% efficiency. Similar products on the market today can store around 10 joules per cubic centimeter.

Dr. Sang-Hoon Bae of Washington University in St. Louis said in a statement, “We made a new structure based on the innovations we’ve already made in my lab involving 2D materials.” “At first, we weren’t interested in energy storage, but while we were studying the properties of materials, we came across a new physical phenomenon that we thought could be used for energy storage. It was very interesting and could be much more useful.”

The work report by Bae and his co-authors only talks about testing the capacitor over 10 cycles, which shows that there is still a long way to go before it can be used in real life. “We’re not quite at our best yet, but we’re already doing better than other labs,” Bae said. For capacitors to be able to charge and discharge very quickly and hold a lot of energy, our next step is to improve the structure of this material even more. To see this material used widely in big electronics like electric cars and other new green technologies, we need to be able to do that without losing storage space over time.

In the same issue of Science, scientists from Cambridge University talk about results that change how people think about making supercapacitors with carbon electrodes store more power. They say, “Pore size has long been thought to be the main way to improve capacitance.” But when commercial carbons with pores measuring nanometers were compared, there wasn’t much of a link between size and capacitance. With nuclear magnetic resonance spectroscopy, we can see that what matters is the level of structural disorder in the capacitors’ domains.

They say that more disorganized carbons with smaller graphene-like domains have higher capacitances because their nanopores store ions more efficiently. “We think that for carbons with smaller domains, the charges are more concentrated, making the interactions between ions and carbon atoms stronger. This makes it easier for ions to be stored.”

The paper makes no mention of how much capacitance is possible when the carbon domains are sufficiently disorganized. This is because it goes against the norm to try to make electronic devices more disorganized than ordered.

BaroMar, an energy storage company, is getting ready to conduct tests on a unique form of grid-level energy storage that utilizes water as its primary component. If it proves effective, this method could offer a more cost-effective solution for maintaining stability in renewable energy sources over extended durations.

The world is making progress towards zero-carbon energy options, but the path ahead is far from simple. In order to achieve net-zero emissions by 2050, the majority of the world’s electricity, approximately 80 percent, will need to be generated from sources such as solar and wind power.

Some countries, such as Portugal, Denmark, and Namibia, have already made significant progress towards achieving zero-carbon grids, which may seem impossible to some. Yet, in order to be universally useful, there is a need for advancements in energy storage and release methods to meet the growing demand caused by these emerging technologies. These demands will differ based on location. Some locations may require a consistent supply, even on overcast days, while others may have fluctuating demand throughout the day.

During the winter or other seasonal low points, it is important to store energy for times when wind power cannot compensate for the decrease in solar power.

This is where BaroMar’s innovative compressed air energy storage (CAES) alternative could prove to be extremely useful.

The technology for CAES has been available for approximately four decades and is widely recognized as a cost-effective method for energy storage, contributing to grid stability. In the conventional approach, the procedure entails the compression and storage of surrounding air in subterranean reservoirs, such as caves or abandoned salt mines. When energy is required, it can be harnessed by utilizing turbines that power a generator to reclaim it.

BaroMar is confident that their innovative approach can surpass the effectiveness of the traditional method and efficiently store energy for extended periods using simple equipment.

Water is the solution. The company intends to establish plants in coastal areas that have access to deep water. The pressure generated from this water will be utilized to replace the high-pressure tanks typically used in conventional CAES systems. This method is significantly more cost-effective.

Instead of envisioning sleek and advanced tanks of pressurized air, picture massive concrete and steel tanks anchored by cages filled with rocks. These would be placed underwater at depths ranging from 200 to 700 meters (650 to 2,300 feet).

Every tank is equipped with water-permeable valves that initially fill them with seawater. Then, during the storage process, the compressor and generator located on land transfer air into the tanks through a hose at varying pressures, typically ranging from 20 to 70 bar (290 to 1,015 psi), depending on the depth. As the air enters the tanks, it expels water.

Then, when energy needs to be extracted, the air is directed back up the hose to power a thermal recovery system and a turbo expander, which in turn drives a generator.

At the sea floor, the tanks are refilled with water and patiently await future utilization.

This system, particularly the tanks, is reported to be much more cost-effective to manufacture due to the stabilizing effect of the pressure from the seawater.

“The tanks are engineered to withstand the various forces exerted by the marine environment, including compressed air and hydrostatic water pressure, during installation and operation,” a representative from Jacobs, in collaboration with BaroMar, clarified to CleanTechnica.

Jacobs is working on a pilot project for the new system to be installed in Cyprus. The goal is to achieve a round-trip efficiency of approximately 70 percent, which refers to the combined loss of energy when adding and withdrawing from an energy store. If accomplished, this would be comparable in efficiency to the world’s largest conventional CAES station in China.

Unfortunately, this water-based pilot project will fall short of matching the energy storage capabilities of the Chinese plants. It will have an initial storage capacity of approximately 4 MWh, which is significantly smaller than the 100-MW, 400 MW/h capacity in Zhangjiakou, China.

Even though it has a lot of potential, there will be problems. These are for things that are meant to stay underwater for decades. To make sure the tanks can be built and work at great depths, they need to go through a lot of geophysical research, feasibility studies, and geotechnological and bathymetric surveys.

However, if BaroMar is right, this new system would be very appealing to many cities around the world. It could also be a much cheaper and easier-to-expand solution. Let us see how things go.

Last year, the world witnessed the inauguration of the tallest wooden wind turbine near the town of Skara, in close proximity to the city of Gothenburg in Sweden. This remarkable feat took place in a country that is widely recognized for its expertise in producing flat-pack wood furniture.

According to Modvion, the company behind this impressive achievement, the turbine has a remarkable 105-meter (345-foot) wooden tower that boasts a towering height of 150 meters (492 feet) with its blades.

According to BBC News, the tower’s 2-megawatt generator became operational and started supplying electricity to the local grid in late 2020, benefiting around 400 households with power.

Wind power is an incredibly cost-effective and environmentally friendly energy source. Nevertheless, there is a cost associated with it. Many turbines are made from steel, which has a significant carbon footprint. With the rise of more powerful turbines, the demand for larger towers has also increased, leading to a higher demand for this metal.

Modvion has developed the “Wind of Change,” which is the first commercial wooden wind turbine tower, as a solution to this problem.

The structure can be constructed on the designated location in seven distinct sections, each consisting of a combined total of 28 individual modules. The tower’s modularity facilitates its transportation via roads and sea, in contrast to conventional steel towers that can be heavy and cumbersome to relocate.

The turbine tower is constructed using 144 layers of laminated veneer lumber, each measuring 3 millimeters in thickness, which have been bonded and compressed together. The timber originated from approximately 200 spruce trees, all of which belonged to the same species commonly utilized for Christmas trees. It is worth noting that these trees were cultivated in a sustainable manner.

“It is our proprietary formula,” stated David Olivegren, a former architect, boat builder, and co-founder of Modvion, in an interview with the BBC.

“Wood and glue have been recognized as an ideal pairing for centuries.” “Furthermore, due to the lower weight of wood compared to steel, it is possible to construct taller turbines using a reduced amount of material,” he stated.

Isolated in the rural landscape of Sweden, the solitary and comparatively diminutive wooden wind tower will not have a substantial impact on the worldwide climate emergency.

However, Modvion is confident that this proof-of-concept holds significant potential and aspires to pursue even more ambitious plans in the future. The company aims to construct 100 wooden towers annually by 2027, potentially on a significantly larger scale than the current scale.

The maximum attainable height of a wooden tower is 1,500 meters (4,921 feet). “A distance of 150 meters (equivalent to 492 feet) appears to be an ideal starting point,” states Modvion on its official website.