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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

Shrinking Birds | Earth Wise

June 5, 2023 By EarthWise Leave a Comment

A new study by researchers at Yale University looks at the way bird morphology is changing in response to the warming climate. As temperatures rise, birds’ bodies are growing smaller, but their wings are growing longer.

In the study, published in the Proceedings of the National Academy of Sciences, the scientists analyzed two independently collected datasets containing 40 years of morphology changes in 129 bird species comprising 52 migratory species in North America and 77 South American species.

In both datasets, similar changes were observed over the 40-year period. The overall trend makes sense given that being smaller and having longer wings both would help birds to stay cool in warmer weather. What was less obvious was that the changes to the birds were much greater among the smallest bird species.

One possible explanation is that smaller species tend to reproduce on a shorter time scale and therefore evolve more quickly. However, the study found no link between generation length and the changes in body size.

Another possible explanation is that smaller species tend to have larger populations, which means there is a greater chance of having individuals with desirable new traits that can get passed on. But the scientists found no link between population size and shifts in body size either.

At this point, it is unclear why smaller birds are shrinking more. More research is needed to figure out why larger birds are slower to adapt to climate change. In general, larger species of animals have an increased risk of extinction. This new research suggests that larger body size exacerbates extinction risk by limiting the ability for birds to adapt to the changes we are making to the climate.

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Birds Are Shrinking as the Climate Warms — and Small Birds Are Shrinking Faster

Photo, posted October 30, 2018, courtesy of N. Lewis / National Park Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The World’s Largest Tidal Device | Earth Wise

June 18, 2021 By EarthWise Leave a Comment

Most of the world’s activity in renewable energy is focused on solar and wind power. The use of both is expanding rapidly. But there is also marine energy to be exploited. Ocean waves and tidal movements hold huge amounts of energy. Estimates are that the European Union could get 15% of its power from marine sources. But ocean energy is currently expensive and there are significant technical challenges still to be overcome.

The world’s largest tidal power device will soon begin testing off the coast of Scotland. The 680-ton, 240-foot-long, airplane-shaped device will be connected to the European Marine Energy Center for testing.

The device, built by the Scottish company Orbital Marine Power, is designed to produce 2 megawatts of electricity, enough to power 2,000 homes. It has a pair of 52-foot-long turbines attached to two wings.

Compared to wind and solar power, the marine energy sector has been much slower to develop because of the many difficulties of working in harsh marine environments as well as the technical challenges associated with harnessing power from waves and tides. But ocean waves and tidal movements hold enormous amounts of energy and have the advantage that they are available at all times, unlike wind and solar energy, which are variable in nature.

Experts say that the future of tidal energy lies with arrays of floating or sea-bottom-mounted turbines that capture the energy of tidal currents in unobstructed waters. There are various places around the world where this is an attractive opportunity, most notably in Nova Scotia’s Bay of Fundy, where the world’s most extreme tides – rising and falling more than 50 feet – contain vast amounts of power.

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The World’s Largest Tidal Power Device Will Soon Begin Testing Off Scotland

Photo, posted May 18, 2017, courtesy of Chris via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.