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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

A Big Year For Rooftop Solar | Earth Wise

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The global capacity of rooftop solar power grew by 49% in 2022.  Overall, the installed amount of rooftop solar grew from 79 gigawatts to 118 gigawatts last year and it is projected to reach 159 gigawatts by the end of this year.  By comparison, a typical nuclear power plant can produce 1 gigawatt; a gas-powered power plant is typically half a gigawatt.

Rooftop solar constitutes a relatively small fraction of the total global installed solar capacity, which is dominated by utility-scale solar arrays.  Total installed solar capacity rose from 950 gigawatts to 1,177 gigawatts last year and is projected to reach 1,518 gigawatts this year.  That is enough power to meet more than half the electricity demand of the European Union.

The rapid growth of solar power can only continue if there is more energy storage put in place to manage the peaks and troughs in solar output.  Countries will also need to upgrade their power grids to be able to transport excess solar power from where it is generated to where it is needed.   Bottlenecks in the grids of most of the leading solar-producing nations are already interfering with further solar development.

The overall potential for rooftop solar is based on the number of rooftops that would be suitable for solar power, which depends on the size, shading, orientation, and location of the roofs.  According to the National Renewable Energy Laboratory, rooftops in the United States have the potential for more than 1,000 gigawatts of solar capacity. Currently, only about 4% of US homes have rooftop solar. 

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Rooftop Solar Grew Nearly 50 Percent Globally Last Year

Photo, posted November 16, 2022, courtesy of Oliver Knight via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fewer Farms In The World | Earth Wise

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A new study by the University of Colorado Boulder looked at the trends in the number and size of farms around the world starting from the 1960s and projecting through the end of the 21st century.

The analysis shows that the number of farms globally will shrink in half while the size of the average existing farms doubles.

The study used data from the UN Food and Agricultural Organization on agricultural area, GDP per capita, and rural population size of more than 180 countries.  The analysis found that the number of farms around the world would drop from 616 million in 2020 to 272 million in 2100.  A key reason for the trend is that as a country’s economy grows, more people migrate to urban areas, leaving fewer people in rural areas to tend the land.

This decline has been ongoing in the US and Europe for decades.  For example, in the US, there were 200,000 fewer farms in 2022 than in 2007.

This trend has troubling consequences.  Larger farms typically have less biodiversity and more monocultures.  The greater biodiversity and crop diversity of smaller farms makes them more resilient to pest outbreaks and climate shocks.

Currently, 600 million farms provide for 8 billion people. By the end of the century, it is likely that half the number of farmers will be feeding even more people.  That is a weighty responsibility for agricultural workers.  Support systems and education for farmers becomes ever more important.

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The number of farms in the world is declining, here’s why it matters to you

Photo, posted January 18, 2011, courtesy of 2010 CIAT / Neil Palmer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Colorful Solar Panels | Earth Wise

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More and more buildings and public spaces are incorporating solar panels and not only just on rooftops.  Some buildings are incorporating power-generating structures all over their facades.

Using solar panels in this way puts some design constraints on buildings because solar panels are typically a deep black color.  This is because solar panels need to absorb light and making them any other color decreases their ability to do so and generate power.  But the problem is that people don’t necessarily want a black building.

One alternative to traditional solar panel design is to use structural sources of color that include microscopic shapes that only reflect specific light frequencies, like the scales on butterfly wings.  But this approach generally leads to iridescence – which might not be what is wanted – and is often quite expensive to implement.

A team of researchers at a university in Shanghai has now demonstrated a way to give solar panels color that is easy and inexpensive to apply and that does not reduce their ability to produce energy efficiently.

The technique involves spraying a thin layer of a material called a photonic glass onto the surface of solar cells.  The photonic glass is made of a thin, disorderly layer of dielectric microscopic zinc sulfide spheres.  Even though most light can pass through the photonic glass, certain colors are reflected back, depending on the sizes of the spheres.  By varying that size, the researchers created solar panels that were blue, green, or purple with only a very small drop in solar panel efficiency.

The solar panels made this way maintained their color and performance under durability testing.  With this new technology, there may soon be colorful solar panels on our buildings.

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Colorful solar panels could make the technology more attractive

Photo, posted December 15, 2021, courtesy of Pete via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fires Are Larger And More Frequent | Earth Wise

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According to a new study by the University of Colorado Boulder, wildfires have gotten much larger and much more frequent across the United States since the year 2000.  The rise in wildfires in recent years has been attributed to the changing climate and the new research shows that large fires have become more common and have been spreading into new areas that previously did not burn.

The researchers analyzed data from over 28,000 fires that occurred between 1984 and 2018 using satellite imagery along with detailed state and federal fire history records.

The results are that there were more fires across all regions of the contiguous U.S. from 2005 to 2018 compared to the previous 20 years.  In the West and East, fire frequency doubled, and in the Great Plains, fire frequency quadrupled.  The amount of land burned each year at least tripled in those regions.

The team discovered that the size of fire-prone areas increased in all regions of the contiguous U.S. in the 2000s, meaning that the distance between individual fires has been getting smaller than it was in previous decades and the fires have been spreading into areas that did not burn in the past.

This comprehensive study confirms what has been assumed by the media, public, and firefighting officials.  The results also align with increasing risk trends such as the growing development of natural hazard zones. Projected changes in climate, fuel, and ignitions suggest that there will be more and larger fires in the future.  More large fires plus intensifying development mean that the worst fire disasters are still to come.

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U.S. Fires Four Times Larger, Three Times More Frequent Since 2000

Photo, posted May 3, 2013, courtesy of Daria Devyatkina via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Reducing Emissions From Shipping And Aviation | Earth Wise

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The global marine shipping and aviation industries are each responsible for about 3% of greenhouse gas emissions.  These are relatively small numbers, but as other industries decarbonize, the contributions from shipping and aviation will loom larger and larger.

In October, both of these industries made commitments to reach net zero emissions by 2050.  How can they do it?  We don’t really have the details of the technologies to be used, and neither do these industries.  But there are ideas being considered.

For both ships and planes, the solution for short-distance trips can be electrification.  Electric planes are in the works for short distances.  Battery-powered container ships are also under development.  But the electrification of longer international and intercontinental routes for both industries is very difficult.  The size and weight of batteries needed for long hauls are major challenges to overcome.

The low-carbon solution slowly being deployed in aviation is sustainable aviation fuel made from renewable sources. Longer term, green hydrogen fuel for planes may be a solution.  For shipping, hydrogen may play an even larger role.  As in the other potential uses for hydrogen, the essential requirement is to be able to produce hydrogen in a way that does not emit greenhouse gases.

There are multiple ways to move towards the decarbonization of both aviation and shipping.  Which will turn out to be the most practical and successful is not yet known.  What is essential is for both industries to follow through on their commitments to research, develop, and deploy zero-carbon solutions.  They appear to have embraced the vision for the future.  Now comes the hard work of achieving that vision.

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Shipping & Aviation Plan To Go Net Zero. How?

Photo, posted August 8, 2014, courtesy of Tomas Del Coro via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wind Power Update | Earth Wise

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The Department of Energy recently released three reports showing record growth in land-based wind energy, a growing number of offshore wind projects, and the continuing reduction in the cost of wind power.

The U.S. installed a record amount of land-based wind energy in 2020.  In total, 16,836 MW of new utility-scale land-based wind power capacity was added during the year, representing $24.6 billion in new wind power projects.  This was more added than from any other energy source and represented 42% of new U.S. energy capacity.

For the year, wind energy provided more than 10% of in-state electricity generation in 16 states.  Notably, wind provided 57% of Iowa’s electricity and more than 30% in Kansas, Oklahoma, South Dakota, and North Dakota.

As wind turbines continue to grow in size and power, they are producing more energy at lower cost.  Turbine prices have gone from $1,800/kW in 2008 to $770-850/kW now.

The pipeline for U.S. offshore wind energy projects has grown to 35,324 MW, a 24% increase over the previous year.   The Bureau of Ocean Management created five new wind energy areas in the New York Bight with a total of 9,800 MW of capacity. 

Distributed wind power, which are systems connected on the customer’s side of the power meter as opposed to those on the utility side, also saw increased growth last year. 

Wind power is a key element in the adminstration’s goal of having a decarbonized electricity sector by 2035.

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DOE Releases New Reports Highlighting Record Growth & Declining Costs Of Wind Power

Photo, posted March 24, 2016, courtesy of Adam Dingley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Gulf Of Mexico Dead Zone | Earth Wise

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Every summer, a so-called dead zone forms in the Gulf of Mexico.  It is primarily caused by excess nutrient pollution from human activities in urban and agricultural areas throughout the Mississippi River watershed. 

When these excess nutrients reach the Gulf, they stimulate excess growth of algae, which eventually die and decompose, depleting oxygen as they sink to the bottom.  These low oxygen levels near the Gulf bottom cannot support most marine life.  Animals that are sufficiently mobile – such as fish, shrimp, and crabs – generally swim out of the area.  Those that can’t move away are stressed or killed by the low oxygen.

A team of scientists funded by the National Oceanic and Atmospheric Administration issues an annual forecast for the dead zone based upon a suite of models that incorporate river flow and nutrient data. 

The 2021 forecasted area is somewhat smaller than, but close to, the five-year measured average for the dead zone, which is 5,400 square miles, roughly the size of the state of Connecticut.   Each year, these forecasts are reported as comparisons to long-term averages, but the problem is that the long-term average is unacceptable.

The Interagency Mississippi River and Gulf of Mexico Hypoxia Task Force has set a goal of reducing the size of the dead zone to a five-year average of 1,900 square miles – about a third of the current average.

Large reductions in nutrient loads have been called for in federal and state action plans for nearly 20 years, but clearly these reductions have not yet been sufficient. The Interagency Task Force continues to provide information for managing nutrient loads in the Mississippi River Basin. 

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Average-sized ‘dead zone’ forecast for Gulf of Mexico

Photo, posted October 6, 2020, courtesy of Christine Warner via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar Cell Greenhouses | Earth Wise

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A recent study at North Carolina State University has shown that it can be feasible to use see-through solar panels in greenhouses to generate electricity.  The idea is to use semi-transparent solar panels on greenhouses that allow some of the light to get in for the plants to grow while making the greenhouses energy neutral or even allowing them to generate more power than they use.

The question is how the semi-transparent solar panels might affect greenhouse crops.  To investigate this issue, researchers grew crops of red leaf lettuce from seed to full maturity under a standard set of growing conditions – temperature, water, fertilizer, and CO2 concentration – but varied the light they get. 

A control group was exposed to the full spectrum of white light while three experimental groups were exposed to light through different types of filters that absorbed the particular wavelengths of light that would be absorbed by different types of semitransparent solar cells.

The researchers paid close attention to characteristics of the lettuce that are important to growers, grocers, and consumers:  general appearance, leaf number, leaf size, and weight.  The results were that the lettuce produced using all three kinds of filtered light was essentially identical to that produced in the control group.    Further research is underway looking at how harvesting various wavelengths of light affects biological processes for lettuces, tomatoes, and other crops.

Getting growers to use solar-powered greenhouses would be very difficult if doing so would result in a loss of productivity.  But given these experimental results, it appears as though the decision will boil down to a simple economic argument about whether the investment in new greenhouse technology would be offset by energy production and its resultant savings.

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Study Finds Plants Would Grow Well in Solar Cell Greenhouses

Photo, posted April 8, 2008, courtesy of Brian Boucheron via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shrinking Alaskan Salmon | Earth Wise

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According to a new study published in the journal Nature Communications, salmon returning to Alaskan rivers have become significantly smaller over the past 60 years.  As a result of climate change and competition from hatchery fish, wild salmon are spending less time at sea and are returning to spawning grounds at younger ages.

The study, by scientists at the University of Alaska at Fairbanks and the University of California Santa Cruz, examined measurements of over 12 million fish collected by the Alaska Department of Fish and Game from 1957 through 2018.  Over that time period, four out of Alaska’s five wild salmon species – Chinook, chum, coho, and sockeye – have shrunk in size.  Chinook salmon is the official state fish of Alaska and they used to stay out at sea for seven years before returning to spawn.  Many are now returning to rivers at just four years old and are on average 8% smaller than they were 30 years ago.

The shrinking size of Alaskan salmon has consequences for people, the economy, and ecosystems in Alaska.   Wild salmon is a staple food for many residents of the state, particularly among indigenous groups.  More generally, Alaska produces nearly all of the wild salmon in the U.S.   Commercial fishing of over 200 million wild salmon in 2019 resulted in $657 million in income.  The fish are also an important food source for bears and other wildlife and the spawning migration of salmon plays an important role in nutrient transportation in Alaskan river ecosystems.


Multiple factors are driving the changes in the salmon population, but the largest effects are the changing climate and the abundance of salmon in the ocean due in part to hatchery production that results in competition for the salmon’s food.

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Alaska’s Salmon Are Significantly Smaller Than They Were 60 Years Ago

Photo, posted September 5, 2019, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Ocean Currents And Climate Change | Earth Wise

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Oceans cover more than 70% of the earth and absorb 94% of incoming solar radiation.  As a result, oceans play a major role in the climate system.  With their massive size and capacity to store heat, oceans help keep temperature fluctuations in check.  But oceans also play a more active role.  Ocean currents are responsible for moving vast amounts of heat around the planet.  

According to a paper recently published in the journal Nature Communications, the world’s strongest ocean currents will experience more intense marine heatwaves than the global average in the coming decades.  These strong ocean currents play key roles in fisheries and ocean ecosystems.  

Sections of the Gulf Stream near the United States, the Kuroshio Current near Japan, the East Australian Current near Australia, and the Antarctic Circumpolar Current will all see more intense marine heatwaves over the next 30 years. 

Scientists from the University of Tasmania and CSIRO in Australia relied on high-resolution ocean modeling to carry out their research.  They confirmed the model’s accuracy by comparing outputs with observations from 1982-2018.  They then used the same model to project how marine heatwaves would alter with climate change out to 2050.

The model projects, for example, that intense marine heatwaves are more likely to form well off the coast of Tasmania, while more intense marine heatwaves along the Gulf Stream start to appear more frequently close to the shore from Virginia to New Brunswick, Canada. 

Marine heatwaves are on the rise globally, but knowing where they will occur and how much hotter they will be will help policymakers, ecologists, and fisheries experts in their regional decision-making. 

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Where marine heatwaves will intensify fastest: New analysis

Photo, posted April 17, 2016, courtesy of Nicolas Henderson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Giant Jellyfish | Earth Wise

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There have been recent news stories about giant jellyfish washing ashore from Maine to the south coast of Massachusetts.  These stories have claimed that some of these lion’s mane jellyfish have been the largest on record and even might be the largest animals in the ocean.

The truth of these accounts is rather suspect.  For one thing, it is rather difficult to measure the size of a jellyfish when it is out of the water.  Gravity compresses and spreads out the bell portion of the animal, and that makes up the bulk of its mass.  For example, a jellyfish bell that measures four feet across on the beach would appear to be much smaller if the animal was floating in the water.

Some claims that lion’s mane jellyfish are larger than blue whales date back a full century and are very much disputable.  The claimed size certainly included the animal’s long tentacles, and such things hardly compare with a blue whale.

In any event, the current spate of jellyfish sightings is not necessarily that unusual.  Many factors influence jellyfish populations, including water temperature and food supply.  It is possible that warming water temperatures may be influencing the jellyfish population this year, but there is not enough data to know for sure.

People do need to be cautious around lion’s mane jellyfish.  They do sting and while their stings are not as bad as those of a number of other species, they can be a problem for people who have allergic reactions.  Furthermore, the stinging cells remain active in a jellyfish that has washed ashore.

Sightings of these animals are continuing, and reports of larger specimens continue as well, even if they don’t compare with blue whales.

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Jellyfish larger than blue whales?

Photo, posted September 13, 2015, courtesy Derek Keats via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wildfire Pollution

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California’s record-breaking wildfires this past season have been an unmitigated disaster with respect to loss of life, property, impact on human health, and in multiple other ways.  And as if all of that was not bad enough, the impact on carbon emissions into the atmosphere was equally catastrophic.  The wildfires were deadly and cost billions of dollars but were also terrible for the environment and for the public’s health.

According to estimates from the U.S. Department of the Interior, the California wildfires released emissions equivalent to about 68 million tons of carbon dioxide into the atmosphere.  That is equal to the emissions from generating one year’s worth of electricity in the state, or about 15% of the total annual emissions in the state of California.

It is a vicious circle in which the changes to the climate that have lengthened the fire season and shortened the precipitation season are creating additional contributions to the warming of the climate.

Over the past century, California has warmed by about 3 degrees Fahrenheit.  That extra-warmed air sucks water out of plants and soils, resulting in trees, shrubs, and rolling grasslands that are dry and primed to burn. That vegetation-drying effect compounds with every additional degree of warming.  Plants lose their water more efficiently as temperatures get higher.

The result is that wildfires are increasing in size both in California and across the western United States. Fire experts at Columbia University estimate that since the 1980s, the warming climate has contributed to an extra 10 million acres of burning in western forests – an area about the size of Massachusetts and Connecticut combined.

It’s a bad situation that is getting worse.

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California’s 2018 Wildfires Have Emitted A Year’s Worth of Power Pollution

Photo, posted October 11, 2017, courtesy of Bob Dass via Flickr. 

Earth Wise is a production of WAMC Northeast Public Radio.

Restoring The Taste Of Tomatoes

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Over the years, tomatoes have been selectively bred for qualities such as size and firmness for shipping purposes and appearance, but selection for flavor has generally been overlooked.  Many of us find that the tomatoes we buy in the grocery store just don’t taste like they used to.  In fact, often they don’t taste like much of anything.  Comparing them to the delicious local-grown varieties we can find during the summer provides evidence for this conclusion.

[Read more…] about Restoring The Taste Of Tomatoes

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