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Progress towards electric school buses

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The U.S. has nearly half a million school buses providing daily transportation for about 20 million students.  Most of these buses are powered by diesel engines which not only dump greenhouse gases into the atmosphere but also fill kids’ lungs with harmful fumes.

Thanks to various federal and state incentive programs, this situation is starting to change.  School districts all over the country are beginning to swap out old diesel buses for emissions-free electric-powered school buses.

Electric school buses are finding their way into school districts of all sizes and demographics.  The first district in the country to go fully electric was in Martinsville, Texas, which last year converted its 4-bus fleet.  The first large urban district to go all-electric was the 74-bus fleet in Oakland, California this summer.

The EPA’s $5 billion Clean School Bus program and many state initiatives are providing incentives for the transition.  Five years ago, there were less than 1,000 electric school buses in the U.S.  Now there are about 5,000 and more than 7,000 additional buses are in the pipeline.

Apart from the climate implications, there is urgency to replacing diesel school buses from a health perspective.  Diesel exhaust is classified as a carcinogen by the World Health Organization, and it contains fine particles and nitrogen oxides, both of which are well-documented asthma triggers.

Electric buses are more expensive than diesel buses, but they are much cheaper to operate. School districts need to put in place charging infrastructure.  The transition is not so easy to accomplish, but it is an important step, and more and more school districts are taking it.

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Slowly but Surely, U.S. School Buses Are Starting to Electrify

Photo, posted May 5, 2021, courtesy of California Energy Commission via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Carbon dioxide and wildfires

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Climate change is a key factor in the increasing risk and extent of wildfires.  Wildfires require the alignment of several factors, including humidity, temperature, and the lack of moisture in fuels, such as trees, shrubs, and grasses.  All of these factors have strong ties to climate variability and climate change.

While the global surge in wildfires is often attributed to hotter and drier conditions, a new study by researchers from the University of California – Riverside has found that increasing levels of a greenhouse gas may be an even bigger factor. 

According to the study, which was recently published in the journal Communications Earth & Environment, carbon dioxide is driving an increase in the severity and frequency of wildfires by fueling the growth of plants that become kindling.

Centuries of burning fossil fuels to produce heat, electricity and to power engines has added alarming amounts of carbon dioxide to the atmosphere.  In fact, atmospheric CO2 levels are measuring more than 420 parts per million, which is a level not seen on earth for 14-16 million years. 

Plants require carbon dioxide, along with sunlight and water, for photosynthesis.  But rising levels of CO2 in the atmosphere are driving an increase in plant photosynthesis – an effect known as the carbon fertilization effect.  This effect can make plants grow bigger and faster. 

Warming and drying are important fire factors.  These are the conditions that make the extra plant mass more flammable.  But the study found that the increase in fires during hotter seasons is driven by the CO2-fueled growth of plants.   

The researchers hope their findings will urge policymakers to focus on reducing carbon dioxide levels in the atmosphere.

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CO2 worsens wildfires by helping plants grow

Current carbon dioxide levels last seen 14 million years ago

Photo, posted January 17, 2024, courtesy of Jennifer Myslivy, BLM Fire/NIFC via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Electric Motors For Aviation | Earth Wise

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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

Electric Cars Getting Cheaper | Earth Wise

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A sticking point for buying electric cars has always been that they are typically more expensive than equivalent gasoline-powered cars.  But increasing competition, government incentives, and falling prices for lithium and other battery materials is changing the equation.  In fact, the tipping point when electric cars are as cheap or even cheaper than internal combustion cars is likely to happen this year for many cars and, in fact, has already happened for some.

Battery production is ramping up for Tesla, General Motors, Ford, and others, creating cost savings from mass production. Companies manufacturing batteries in the United States are receiving government subsidies as part of a drive to establish a domestic supply chain and reduce dependence on China.  Before anyone cries foul, it should be noted that globally, oil companies received a trillion dollars in subsidies last year.  The Inflation Reduction Act is making it cheaper for automakers to build electric cars (provided they do it in the United States using US materials) and cheaper for consumers to buy them because of tax credits.

Multiple companies have lowered the price of their electric vehicles in recent months, including both the Tesla Model 3 and Model Y, which are the best-selling electric cars in the United States. GM’s electric Equinox crossover will start at about $30,000, which is still about $3,400 more than the gas-powered version.  But once the electric vehicle tax credit is figured in, it will actually be cheaper.

Electric cars are already cheaper to own and operate because of the much lower cost of powering with electricity instead of gas as well as the greatly reduced maintenance costs for the vehicles.  Once the purchase price of these cars is less than that of gas-powered cars, the economics becomes a no-brainer.

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Electric Vehicles Could Match Gasoline Cars on Price This Year

Photo, posted May 11, 2021, courtesy of Chris Yarzab via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Contrails And Climate Change

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The white wispy trails of condensation produced by the exhaust from aircraft engines have been the subject of a popular conspiracy theory for quite a while.  The story goes that the long-lasting condensation trails are actually “chemtrails” composed of chemical or biological agents left in the sky by aircraft and are intentionally sprayed for a variety of nefarious purposes undisclosed to the general public.  This story, of course, is nonsense.

But while contrails are not deliberate efforts to modify weather, control population, manipulate psychology, or any of the other bizarre things attributed to them, it turns out that they are having unfortunate effects on the climate.

It turns out that contrails are creating an often-invisible thermal blanket of cloud across the planet that has a significant effect on atmospheric temperatures.  Contrails are essentially human-made clouds that form above 25,000 feet where the air is moist and colder than -40 degrees Celsius.  At times, contrails stick around in the sky, either as tight, white lines like chalk marks, or by spreading to create thin layers of ice clouds.  At any one time, contrail-created clouds cover more than half a percent of global skies.

Research has shown that when contrails are around, nighttime temperatures can go up appreciably.  After 9/11, when all U.S. flights were grounded for three days, the difference between daytime and nighttime temperatures actually increased by about 3 degrees Fahrenheit because nights were cooler.

The effects of aviation on climate, both from the CO2 emissions from aircraft engines and from these contrail effects are becoming an increasingly important issue. To complicate matters further, as aircraft engines become more efficient, they will create more, whiter, and longer-lasting contrails.

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How Airplane Contrails Are Helping Make the Planet Warmer

Photo, posted May 15, 2012, courtesy of Mike Lewinski via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Power From The Sun’s Heat

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When we think of solar power, we usually are talking about the panels that generate electricity using the photovoltaic effect.  These panels are on millions of rooftops around the world and in utility-scale solar farms.   There are also solar water heating systems that use the sun’s heat to provide hot water for homes and businesses.

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The Changing Face Of Air Pollution

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Air pollution in cities is a global problem that has reached crisis proportions in places like China and India.   In our country, since the Clean Air Act was passed in 1970, there has been a great deal of effort exerted in controlling pollution from vehicles.  A combination of pollution-limiting changes to engines, fuels, and pollution control systems has significantly reduced the amount of air pollution associated with the transportation sector.

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Energy From Evaporating Water

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Researchers at Columbia University have demonstrated a potential new energy harvesting technique based on the natural evaporation of water.   Every day, vast amounts of water evaporate from the surfaces of lakes and rivers, a process powered by the heat energy of the sun.   The amount of energy involved is enormous but generally speaking is not something we can tap into.

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Lawnmower Pollution

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Over 50 million Americans mow their lawns each week, which uses 800 million gallons of gas per year and produces tons of air pollutants.  Garden equipment engines were completely unregulated with respect to emissions until the late 1990s and still emit high levels of carbon monoxide, volatile organic compounds, and nitrogen oxides.  In fact, gas mowers and their relatives like leaf blowers and edgers produce 5% of the air pollution in this country.

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