New Transparent Aerogel For Better Solar Power Plants

It is modular, easy to implement and can generate industrial process heat at up to 1,300 degrees Fahrenheit. This is the path for a new concentrating solar energy system equipped with heat-absorbing tiles in the form of a transparent, sponge-like airgel. The ultimate goal is to scrub fossil energy from areas in the industrial sector that are difficult to decarbonize. Where are all the people who thought concentrating solar energy was a dead end?

Concentrating solar energy on everyone: The report of my death was …

Concentrating solar energy systems are designed to provide heat, not electricity. They work by collecting ambient sunlight from many different points, typically from a series of specialized mirrors or a series of long troughs. The concentrated light is focused on a central point in the case of mirrors, or long tubes in the case of troughs. The heat is then transferred to a transportable, recirculating liquid, such as molten salt or a specialized oil.

Typically, the hot liquid is then used to boil water to generate steam. In turn, steam is used to power turbines to produce electricity. This raises the question of why not just use solar cells to generate electricity directly and skip it all with making steam. After all, the steam thing adds more infrastructure, more complexity and more cost.

It was the basic argument used by critics of concentrating solar technology in the early years. However, one of the attractions of concentrating solar energy is the energy storage angle. Once the circulating liquid is heated, it can potentially stay warm for hours, allowing a steam power plant to keep grinding out kilowatts long after the sun has set.

… An exaggeration

Despite a barrage of criticism, the U.S. Department of Energy began promoting solar energy concentration as a showcase for U.S. know-how on clean energy throughout the Obama administration. The Department of Energy continued to carry the torch for further technology improvements under the administration that followed the Obama administration and has since been replaced by the Biden administration. The projects included some interesting features in the field of supercritical carbon dioxide and other innovations aimed at enabling solar energy to compete mano-a-mano with fossil energy for control of the country’s electricity grid.

It’s all right to decarbonize the electricity generation business, but it still leaves the area of ​​industrial process heat open.

Earlier this year, the Ministry of Energy’s National Renewable Energy Laboratory ran the figures, outlining the need to do something about industrial process heat, such as paper mills and other industrial processes that require heat.

“Fossil fuels account for about 87% of all manufacturing fuel consumption in the United States, which is broadly the same as four decades ago,” NREL noted, stressing the need for a strategic approach.

Slightly ironically, a good portion of the manufacturing’s fuel consumption is related to oil refining. Based on figures from 2014, NREL estimates that the oil industry is by far the most significant user of fuel for industrial process heat, clocking in at 2-1 / 2 times the second largest user.

By counting down from oil refineries in the order of magnitude, NREL ranks the largest industrial process heat users as paper mills (excluding newsprint), cardboard mills, iron and steel production, basic chemical products and ethyl alcohol production. Together with petroleum, these sectors account for about half of all industrial process heat used in the United States.

New life to concentrate solar energy

Among other solar technologies, the new NREL report indicates that concentrating solar systems using parabolic trough collectors may be the key to an effective strategy for decarbonizing industrial processes.

“PTC technology when combined with thermal energy storage (TES), not only has the greatest potential in terms of distribution over geography and time, but also in terms of current IPH requirements, “says NREL enthusiastically, adding that” PTC with TES represents displacement of almost 2,500 trillion Btus of combustion fuels, equivalent to 137 million. tonnes of CO2, or about 15% of all CO2 emissions from industrial combustion. “

All this is to say that improvements in parabolic trough technology can make a significant dent in the emissions of industrial energy users.

This is where the new airgel comes into the picture. Last week, the University of Michigan announced that it is using a $ 3.1 million grant in the energy department for the development of a new “solar-transparent airgel” for use in concentrating solar power plants.

“Parabolic trough power plants, which are currently the most widely used solar heating technology, use a kind of mirrored halfpipe to concentrate sunlight on receiver tubes carrying a circulating liquid. That liquid absorbs heat and transports it for storage or use – generates electricity or produces fuel and other chemicals, “the school explains.

The problem is that conventional trough-style systems do not heat the circulating liquid high enough to power many industrial processes. Using special coatings, they can reach around 1,000 degrees Fahrenheit, enabling them to cover some industrial applications, but many more remain untouched, which explains why scientists have been looking for aerogels and other new coatings that are more durable and more efficient.

A love letter from NASA to Earth

Given that the United States dominated the early years of the global solar industry through its space program, it is fitting that the research team from the University of Michigan has been inspired by the ceramic aerogels used in the space shuttle.

An airgel is an extremely light, porous material. Clays and polymers are among the materials commonly used in the manufacture of aerogels. However, to get a complete picture of what is going on with aerogels, NASA invites you to imagine making gelatin from powder and water, and then removing all the water, but allowing the gelatin to retain a firm shape and structure. – without wiggling, that is.

Both NASA and the Ministry of Energy are very interested in aerogels due to their superior insulating properties, which explains why, among other things, they have appeared on the outside of the space shuttle.

The trick is to let in the most sunlight to achieve the most efficient heat generation, while preventing the most heat from escaping. The team has worked with the company AeroShield Materials to develop their new transparent airgel tiles, which are dimensioned for use in a standard 4-meter satellite dish.

Durability also comes into play. With the assistance of the company Forge Nano, the airgel tiles have a special, atom-thin coating that prevents them from decomposing or cracking under high heat.

The team is convinced that the new airgel will allow parabolic solar energy systems to heat a circulating liquid up to 1,300 degrees Fahrenheit. They also envisage a modular, scalable system that can be widely implemented across industrial plants.

Next step for concentrating solar energy

With the new funding in hand, the team will be able to construct a pilot-scale demonstration system. The plan also includes the development of production strategies that increase efficiency and lower costs.

In addition to the $ 3.1 million for the demonstration model, the team also won a $ 300,000 grant from the Department of Energy to identify materials that provide an even more effective balance between heat gain and heat loss in concentrating solar systems.

It seems that the solar cell industry is entering the age of transparency. In addition to transparent aerogels for concentrating solar systems, photovoltaic technology is also undergoing a renewal of transparency.

Follow me on Twitter: @TinaMCasey.

Photo: “A solar transparent airgel is placed in a unit that will apply a nuclear-thick coating for use in solar thermal power plants.” Image credit: Evan Dougherty / Michigan Engineering.

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