motors

Storing Energy In Abandoned Mines | Earth Wise

October 10, 2023 By EarthWise Leave a Comment

An international study led by researchers from Austria has developed a novel way to store energy by transporting sand into abandoned underground mines. The technique is called Underground Gravity Energy Storage or UGES.

As the world deploys growing amounts of wind and solar energy, it is increasingly important to find ways to accessibly and efficiently store that energy to eliminate the inherent variability of the generation. There are many ways to store energy on a short-term basis – most commonly in batteries – but cost-effective long-term storage is still in its early stages.

The UGES technique generates electricity by lowering sand into an underground mine thereby converting the potential energy of the sand into electricity by the same regenerative braking effect used in hybrid and electric cars. The lowering sand operates a generator. Storing energy is accomplished by lifting the sand from the mine with electric motors to an upper reservoir where it is ready for the next cycle. By its nature, this storage technique has an indefinite duration, unlike batteries, for example, which lose energy to self-discharge.

The main components of UGES are the mineshaft, motor/generator, sand storage sites, and mining equipment. The deeper and broader the mineshaft, the more power can be extracted from the plant, and the larger the mine, the more energy can be stored. Mines generally already have the basic infrastructure needed and are connected to the power grid. The researchers estimate that there is global potential of 7 to 70 TWh of storage. Total global generating capacity is currently at the lower end of that range.

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Turning abandoned mines into batteries

Photo, posted October 21, 2020, courtesy of Christine Warner-Morin via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Electric Motors For Aviation | Earth Wise

July 25, 2023 By EarthWise Leave a Comment

Aviation contributes about 3% of global greenhouse gas emissions. Its carbon footprint is one of the more difficult ones to reduce. Electrifying planes would shrink that footprint considerably, but it represents a significant technical challenge. To date, only small all-electric planes have gotten off the ground. The electric motors in those planes generate hundreds of kilowatts of power. To power large planes, like commercial airliners, megawatt-scale motors are required.

A team of MIT engineers is developing a 1-megawatt motor that could be a key step towards electrifying commercial aircraft. They have designed and tested major components of the motor and have calculated how the completed design could generate one megawatt of power at a weight and size competitive with existing small aircraft engines.

To be suitable for aircraft use, motors have to be compact and lightweight. The more power electric motors generate, the bigger they are and the more heat they produce. Cooling motors requires additional components that take up space and add significant weight. The MIT motor design and associated power electronics are each about the size of a typical checked suitcase and weigh less than an adult passenger.

Once the MIT team can demonstrate an entire functional motor, the design could be used to power regional aircraft and could be the enabling element of hybrid-electric propulsion systems for jet aircraft. Possible future configurations could make use of multiple one-megawatt motors powering multiple fans distributed along aircraft wings.

Electrification of aircraft is a slow but steady area of development and technologies such as that being developed at MIT could end up meeting the practical needs of the aircraft of the future.

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Megawatt electrical motor designed by MIT engineers could help electrify aviation

Photo, posted September 14, 2019, courtesy of Dylan Agbagni via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Hybrid-Electric Aircraft

May 20, 2019 By EarthWise Leave a Comment

The commercial aviation industry is a major source of carbon dioxide emissions and, as other industries try to move towards decarbonization, its share is getting larger. But reducing emissions from aircraft is challenging because powering planes without burning fossil fuel is hard to do.

The biggest problem is that powering aircraft with electric motors instead of fossil fuel motors requires so much energy that the batteries needed to supply it become impractically heavy. While research goes on to develop lighter-weight batteries, an interim concept may pay dividends.

Just as hybrid cars represent a stepping stone towards full electrification, hybrid-electric aircraft may be a way to obtain substantial reductions in aircraft emissions. The idea is to use battery-powered electric motors to power planes, but to greatly reduce the capacity requirements of the batteries by having an on-board fossil-fuel generator to charge the batteries and supply additional needed power.

A study by the University of Illinois looked at the potential emissions reductions for hybrid-electric aircraft taking into account the emissions associated with generating the electricity that charges the batteries in the plane. The requirements in the study were that the plane needs to be able to carry the same number of passengers and travel the same distance as current aircraft.

The results were that a drivetrain that gets 50% of its power from battery charge reduced emissions by about 50% over the full lifecycle of the plane.

As batteries get lighter and the electric grid gets greener, the possibility of making major reductions in aircraft carbon emissions looks increasingly realistic. But there is a long way to go.

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Study Examines Commercial Hybrid-Electric Aircraft, Reduced Carbon Emissions

Photo, posted September 26, 2014, courtesy of Jeff Turner via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Rare Earths From Mining Waste

May 3, 2019 By EarthWise Leave a Comment

The 17 rare earth elements have become important parts of much of modern technology. Despite their name, most of these elements are relatively plentiful in the earth’s crust, but because of their geochemical properties they are typically dispersed and not often found concentrated in minerals. As a result, economically exploitable ore deposits are uncommon. There are no significant sources in the U.S.

Rare earths play important roles in high-performance magnets, electric motors in vehicles, wind turbines, microphones and speakers, and in portable electronics like cell phones. As these applications become ever larger, the need for additional sources of rare earths increases.

Researchers at Idaho National Laboratory and Rutgers University have studied a method for extracting rare-earth elements from mining waste that could greatly increase the world’s supply of these valuable materials.

It turns out that large amounts of rare earths exist in phosphogypsum, a waste product from producing phosphoric acid from phosphate rock. The U.S. alone mined 28 million tons of phosphate rock in 2017. (Phosphoric acid is used in the production of fertilizers and other products).

The researchers estimate that more than a billion tons of phosphogypsum waste sits in piles at storage sites across the U.S. alone. World-wide, about 100,000 tons of rare earth elements per year end up in phosphogypsum waste. This compares to the total current world-wide production of rare earth oxides of 126,000 tons.

The researchers studied methods for extracting the elements from the waste. A method utilizing a common environmental bacterium showed great promise.

There are concerns about residual radioactivity and other environmental issues in dealing with the waste material, but the world’s supply of rare earth elements might become much greater based on this research.

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Critical Materials: Researchers Eye Huge Supply of Rare-Earth Elements from Mining Waste

Photo, posted June 19, 2015, courtesy of David Stanley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Affordable Electric Cars

May 1, 2019 By EarthWise Leave a Comment

The main reasons that electric cars haven’t taken over are that they didn’t drive far enough on a charge, it took too long to charge them, and, most of all, they cost too much.

In recent years, the problem with driving range has steadily been disappearing as electric cars that can go over two hundred and even over three hundred miles on a charge have entered the market. Charging time has also become less of a problem. Tesla’s network of Superchargers can provide 200 miles worth of charge in half an hour and their next generation of chargers, which are just starting to appear, can cut that time much further.

As for cost, a new report by transportation analysts at Bloomberg New Energy Finance predicts that electric vehicles will be cost-competitive with combustion-engine cars by 2022.

The main reason is that the cost of EV batteries has been plummeting. In 2015, batteries made up 57% of the total cost of an electric vehicle. Today, that number is down to 33% and is expected to drop to 20% by 2025. In addition, the cost of electric powertrain systems is also dropping. The Bloomberg report predicts that over the next decade, costs for motors, inverters, and power electronics could be 25 to 30% cheaper than today.

The cost of electric vehicles has been dropping faster than predicted. Bloomberg’s report on the subject in 2017 predicted cost parity in 2026. Last year, they changed it to 2024. And now, they are saying 2022.

Given that electric cars are much cheaper to drive than gasoline cars, finding reasons not to drive them is getting harder to do.

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Electric Cars Could Be As Affordable as Conventional Vehicles In Just Three Years

Photo, posted November 17, 2018, courtesy of Jakob Harter via Flickr.

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Turning Heat Into Electricity

February 19, 2018 By EarthWise Leave a Comment

Many of our technologies produce waste heat. Internal combustion engines are a prime example, but all our industrial processes, motors, electronics and other machinery turn some (and, in many cases, most) of the energy it takes to run them into heat that just goes into the environment.