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Green transit in London

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TfL – Transport for London – the operator of the transportation system in Britain’s capital city, has signed a deal with EDF Renewables to purchase electricity from a huge solar array to be erected next year in Essex.  TfL has the goal of powering 100% of its entire transit system – including its sprawling underground railway network – with renewable electricity by 2030.

The forthcoming 1,000-acre solar facility will also transform low-quality farmland by incorporating the planting of trees and hedgerows as well as setting aside some areas for natural regeneration, attracting a greater number of species of plants and animals, expanding biodiversity in the area.  Looking after nature and protecting the environment are key elements in TfL’s contracts, in keeping with its wider goals to be greener, more sustainable, and well-adapted to climate change. 

The solar facility will generate 80 gigawatt-hours annually for the transit authority, roughly enough electricity to power 29,000 homes, comprising about 20% of its total output.  Powering the entire sprawling London underground railroad network is equivalent to powering 420,000 homes.  Over the course of the 15-year contract with EDF, TfL expects to save over 30,000 tons of carbon from its operations.

TfL plans to secure 70% of its electricity use from power purchase agreements for renewable electricity from various sources with the remainder from green tariffs.  The Mayor of London has set the goal for London to be a net zero carbon city by 2030.

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London Inches Closer to Running Transit System Entirely on Renewable Power

Photo, posted March 5, 2017, courtesy of Albert Koch via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Saharan dust and solar power

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The world is a big place but even things that are far away can have serious local consequences.  The effects of distant Canadian wildfires on air quality in Florida is a good example.

Europe is increasingly becoming reliant on solar energy to meet its targets for climate change mitigation and energy security.   According to new research by four Hungarian universities, mineral dust carried on the wind from the Sahara Desert is not only reducing electricity generation from solar power across Europe but it is also making it harder to predict what gets generated.

The Sahara releases billions of tons of fine dust into the atmosphere each year.  Tens of millions of tons reach European skies where the tiny particles scatter and absorb sunlight, reduce the amount of light reaching the surface, and even promote cloud formation.   All of these things reduce the output of photovoltaic systems.

In addition, conventional weather forecasting tools don’t consider the effects of Saharan dust events, so that scheduling of solar power for the energy system becomes less reliable.  Incorporating these events into new forecast models will be essential.

Apart from the atmospheric effects of the dust, there are also long-term impacts due to dust contaminating and eroding the physical infrastructure of solar panels thereby further reducing their efficiency and increasing maintenance costs.

Over time, south-to-north transport of Saharan dust is likely to become more pronounced due to a steeper thermal gradient.  Currently, the quantities of atmospheric dust, the dynamics of its transport, and the physical properties of the dust itself are not very well understood.  Understanding these things will be crucial for Europe’s energy future.

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The shadow of the wind: photovoltaic power generation under Europe’s dusty skies

Photo, posted March 11, 2023, courtesy of Mark Wordy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A big year for battery storage

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A decade ago, the ability of utilities to store large amounts of electricity in batteries was basically nonexistent.  In the past several years, growth in battery storage systems has exploded.  As of the end of November, the US had about 24 gigawatt-hours of storage capacity in place.  This is 71% more than just a year ago.  Nearly half of the battery storage in the US is located in California.  Texas, Arizona, and Nevada are also leaders in deploying battery storage.

Battery storage allows solar and wind generating plants to keep operating when there is reduced demand for their output and have the electricity that they produce be available later when demand rises.  Storing this excess electricity essentially extends the hours of the day when clean energy can be used.

Equally important, the existence of battery storage reduces the need for peaker plants, the fossil-fueled power plants that only turn on at times of peak demand, such as during hot afternoons.

There are 1,000 peaker plants in the US and they are generally heavily polluting, inefficient, and expensive to operate.  Some 63 million people live within a three-mile radius of one of them and are exposed to harmful pollutants like nitrogen oxides and sulfur dioxide.  Peaker plants also release more greenhouse gases than other power plants do for every unit of electricity they generate.

Many battery storage facilities are co-located with, or otherwise support, solar energy plants.  The amount of solar energy in the US is growing rapidly and surpassed the 100-gigawatt mark in 2024.  As solar power continues to expand, so will battery energy storage.

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Battery projects soared again in 2024

Photo, posted August 3, 2024, courtesy of the Bureau of Ocean Energy Management via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Solar-powered desalination

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People in remote, low-income regions far from the ocean often need to meet their water needs from groundwater and groundwater is becoming increasingly saline due to climate change.  Desalination of brackish groundwater is a huge and largely untapped source of drinking water, but there are challenges in making the process efficient and reliable.

Engineers at MIT have developed a solar-powered desalination system that requires no batteries or external power sources and is capable of producing large quantities of clean water despite the variations of sunshine throughout the day.

The system is based on the process of electrodialysis and consists of water pumps, an ion-exchange membrane stack, and a solar panel array.  What is unique about it is that it makes use of sensors and a control system that predicts the optimal rate at which to pump water through the system based on the output of the solar panels.  As a result, it uses nearly all of the electricity generated to produce clean water and does not need stored or grid-based energy.

The MIT engineers tested a community-scale prototype on groundwater wells in New Mexico over a six-month period.  The system harnessed on average over 94% of the electricity generated by its solar panels and produced as much as 5,000 liters of water per day despite large variations in weather and sunlight.

The new renewable-powered, battery-free system could provide much-needed drinking water at low cost, especially for communities where access to seawater and to grid power are limited.  The team plans to further test and scale up the system so it can supply larger communities and even whole municipalities with low-cost drinking water.

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Solar-powered desalination system requires no extra batteries

Photo courtesy of Shane Pratt.

Earth Wise is a production of WAMC Northeast Public Radio

Potential for floating solar

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As installations of utility-scale solar power continue to expand around the world, there is the issue of where to put them.  They do take up considerable amounts of space and, in many places, available land is at a premium.

An alternative to taking up available land with solar panels is to deploy them on the surfaces of lakes and reservoirs.  A study by researchers at Bangor and Lancaster Universities in the UK calculated the potential electrical output for floating photovoltaic installation on nearly 68,000 lakes and reservoirs around the world.  The lakes and reservoirs selected were no more than 6 miles from a population center, were not in a protected area, and didn’t dry up and didn’t freeze for more than six months each year.  The calculations were based on covering just 10% of the surface area of the bodies of water.

The calculations were evaluated country-by-country.  Five countries could meet their entire electricity needs by floating installations including Papua New Guinea, Ethiopia, and Rwanda.  Many countries, mostly in Africa, South America, and Central Asia, could get between 40% and 70% of their electricity this way.  Most European countries could only meet a few percent of their electricity needs from floating solar, but even that could be significant. 

There are other benefits to floating solar apart from freeing up land.  The panels stay cooler, making them more efficient, and reservoirs lose less water through evaporation and the growth of algal blooms is reduced because there is less light reaching the water.

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Some countries could meet their total electricity needs from floating solar panels, research shows

Photo, posted November 25, 2015, courtesy of Smabs Sputzer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wind And Solar Pass Coal | Earth Wise

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For the first five months of this year, wind and solar generated more electricity than coal in the United States.  This is a first.  Total renewable energy generation exceeded coal-fired power in both 2020 and 2022, but that counted hydroelectric power as one of the renewable sources.

This year, wind and solar alone generated a total of 252 terawatt-hours of energy through May compared with coal’s output of 249 terawatt-hours.  Hydropower generated an additional 117 terawatt-hours during that period.

While solar and wind power have been expanding at a rapid rate, the biggest change this year has been a precipitous drop in coal-fired generation due to a combination of low natural gas prices, a mild winter, and a series of coal plant retirements.

Coal generated almost half of the country’s electricity as recently as 2008.  Since then, coal has steadily declined as older coal plants shut down and were replaced by natural gas plants and renewable energy sources.  The coal industry had a bit of a reprieve last year when natural gas prices spiked in response to the disruptions in gas supplies in Europe due to the war in Ukraine.  The benchmark for natural gas prices – known as Henry Hub – was $8.81 in August 2022.  In May of this year, it was $2.15.  Given this trend, the demand for coal has steadily declined. 

The US has retired another 7% of the coal fleet – 14 gigawatts of capacity – since the start of 2022.  Meanwhile, power companies have added 22.5 GW of wind and solar capacity in just the past 12 months.

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In a First, Wind and Solar Generated More Power Than Coal in U.S.

Photo, posted September 20, 2016, courtesy of Bureau of Land Management via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Water For Arizona | Earth Wise

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The Phoenix area is the fastest growing region in the country.  Arizona’s two major sources of water – groundwater and the Colorado River – are dwindling from drought, climate change, and overuse.  Officials in the state are considering a radical plan to construct a desalination plant off the Mexican coast that will take the salt out of seawater, and then pipe that water hundreds of miles, much of it uphill, to Phoenix.

The project is the brainchild of the Israeli company, IDE, which is one of the world’s largest desalination companies.  IDE has asked Arizona to sign a 100-year contract to buy water from the project. 

There are multiple complications surrounding the plan.  Desalination plants are common in California, Texas, and Florida, and in more than 100 other countries.  But the Arizona project is unusual because of the distance involved and because the state is landlocked.  The water would have to travel 200 miles and climb 2,000 feet along the way.

There is also the issue of waste brine, which is a major output of desalination plants.  In this case, the brine would flood the northern Gulf of California, potentially threatening a productive fishery.  In addition, the pipeline, as well as electrical transmission lines, would have to go through the Organ Pipe Cactus National Monument, a UNESCO biosphere reserve.

The plant would be located in Puerto Peñasco, a struggling town with its own water problems.

With booming home construction going on in the Phoenix area, the need for more water continues to grow.  Whether this plan will be approved by Arizona and by Mexico remains to be seen.

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Arizona, Low on Water, Weighs Taking It From the Sea. In Mexico.

Photo, posted September 26, 2008, courtesy of Dan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Solar Parking Lots In France | Earth Wise

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France has passed legislation that will require all parking lots with more than 80 spaces to be covered over by solar panels.  This is part of a broader effort to put solar panels on vacant lots, empty land alongside roadways and train tracks, and even some farmland.  The overall program would add 11 gigawatts of solar power to the French electricity grid.

The legislation applies to both new and existing parking lots.  Owners of parking lots with more than 400 spaces would have 3 years to comply, while owners of lots with 80 to 400 spaces would have five years.

To produce 11 gigawatts of solar output, about half a percent of France’s urban land would need to be covered with solar panels.  This is quite a bit, but not an insurmountable obstacle.  Parking lots, however, could only provide a fraction of what is needed.  It would take something like 8 million parking spaces covered with solar panels to produce that much power.  That is probably at least twice as many as France has.

Several countries, most notably Germany, already have mandates for new construction to incorporate renewable energy.  This includes solar panels, biomass boilers, heat pumps, and wind turbines.  Many parking lots in southern Europe already have sunshades over them, which would make it pretty easy to install solar panels.  This is much rarer in cooler countries.

France is pursuing this policy to reduce its dependence on nuclear power, which currently provides 70% of the country’s electricity.  Apart from the general trend of opposition to nuclear power, reliance upon it during increasingly common droughts is problematic as the power plants require significant amounts of water to operate.

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France’s plan for solar panels on all car parks is just the start of an urban renewable revolution

Photo, posted February 11, 2008, courtesy of Armando Jimenez / U.S. Army Environmental Command via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Race For American Lithium Mining | Earth Wise

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The auto industry is making a massive transition from gas-powered cars to electric cars.  The exploding electric vehicle market has set off what some call a global battery arms race.  Battery manufacturers are urgently trying to source the raw materials needed to make batteries, which presently include cobalt, nickel, graphite, and lithium.  There is encouraging progress in reducing and even eliminating cobalt and nickel from electric car batteries, but so far lithium seems to be essential.

The International Energy Agency has named lithium as the mineral for which there is the fastest growing demand in the world.  Estimates are that if the world is to meet the global climate targets set by the Paris Agreement, at least 40 times more lithium will be needed in 2040 compared with today.

According to the US Geological Survey, the US has about 9 million tons of lithium, which puts it in the top 5 most lithium-rich countries in the world.  Despite this, our country mines and processes only 1% of global lithium output.  Most of the rest comes from China, Chile, and Australia.  Being dependent upon these foreign sources is a serious concern for national security.

There is only one operational lithium mine in the US at present.  Multiple companies are pressing to get more mining projects in operation, including sites in North Carolina and Nevada.  But there are serious environmental problems associated with lithium mining and there is considerable local opposition to establishing the mines.

The US wants to be a leader in the global race to build the batteries that will power the green transition but it is a complicated situation that combines both undeniably important benefits as well as very real dangers.

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Powering electric cars: the race to mine lithium in America’s backyard

Photo, posted January 18, 2022, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Stretchy And Washable Batteries | Earth Wise

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Wearable electronic devices are a big market but there are limitations created by the properties of the batteries that operate them.  The ideal battery for wearable electronics would be soft and comfortable, stretchable, and washable.  Researchers at the University of British Columbia have recently developed just such a battery.  The work has been described in a new paper published in Advanced Energy Materials.

The battery encompasses a number of engineering advances.  Traditional batteries are made from hard materials encased in a rigid external shell.  The UBC battery is stretchable because its key components are ground into small pieces and then embedded in a rubbery polymer.  Ultra-thin layers of these materials are then encased in the same polymer.  This construction creates an airtight, waterproof seal.

The batteries survived 39 cycles in washing machines using both home and commercial-grade appliances.  The batteries came out intact and functional.

The batteries use zinc and manganese dioxide chemistry which is safer than lithium-ion batteries in case they break while being worn.

The materials used are low-cost, so if the technology is commercialized, it will be cheap.  When it is ready for consumers, it is likely to cost no more than existing batteries.  Work is underway to increase the power output of the batteries and their cycle life.  There is already commercial interest in the technology.

There are many potential applications for such batteries.  Apart from watches and medical monitors, they might also be integrated with clothing that can actively change color or temperature.  If the batteries are commercialized, they will make wearable power comfortable, convenient, and resilient.

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Stretchy, washable battery brings wearable devices closer to reality

Photo, posted April 15, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wind Farms Slowing Each Other Down | Earth Wise

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Offshore wind is booming in Europe.  The expansion of wind energy in the German Bight and Baltic Sea has been especially dramatic.  At this point, there are about 8 gigawatts of wind turbines in German waters, the equivalent of about 8 nuclear power plants.  But space in this region is limited so that wind farms are sometimes built very close to one another.

A team of researchers from the Helmholtz Center Hereon, a major German research institute, has found that wind speeds downstream from large windfarms are significantly slowed down.  In a study published in the journal Nature Scientific Reports, they found that this braking effect can result in astonishingly large-scale lowering of wind speeds.

On average, the regions of lowered wind can extend 20-30 miles and, under certain weather conditions, can even extend up to 60 miles.  As a result, the output of a neighboring wind farm located within this distance can be reduced by 20 to 25 percent.

These wake effects are weather dependent.  During stable weather conditions, which are typically the case in the spring in German waters, the effects can be especially large.  During stormy times, such as in November and December, the atmosphere is so mixed that the wind farm wake effects are relatively small.

Based on their modeling, it is clear that if wind farms are planned to be located close together, these wake effects need to be taken into account.  The researchers next want to investigate the effects that reduced wind speeds have on life in the sea.  Ocean winds affect salt and oxygen content, temperatures, and nutrients in the water.  It is important to find out how reduced winds might affect marine ecosystems.

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Are wind farms slowing each other down?

Photo, posted November 23, 2011, courtesy of David J Laporte via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Solar And Wind Power In The U.S.

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According to the U.S. Energy Information Administration, both wind and solar power are contributing more and more to total electrical generation in the United States.  For the first 8 months of 2019, the combination of wind and solar power accounted for almost 10% of U.S. electrical generation.

Solar, including small-scale PV systems on home rooftops, grew by almost 14% compared to the first eight months of 2018 and accounted for more than 2.7% of total electrical output.  In fact, small-scale solar generation increased by 19% and provided nearly a third of all the solar power in the country. 

Wind energy in the U.S. increased by 4.4%, accounting for almost 7% of the country’s electricity.

Overall, renewable energy sources – which include biomass, geothermal, hydropower, solar, and wind – accounted for 18.49% of net domestic electrical generation during the first 8 months of 2019.  The non-hydro renewable sources actually accounted for over 11% of total electricity production and saw a year-over-year growth of 6%. 

Outside of renewables, nuclear-generated electricity declined by 0.6% and coal power dropped by almost 14%.  Much of the coal generation was replaced by natural gas, which grew by 6.5% compared to the previous year.

Renewables now accounting for nearly 20% of overall electricity generation in the US represents significant progress.  But the variations by state continue to be substantial.  For example, while Vermont gets 99% of its power from renewables, Ohio gets only 2%. 

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Solar and wind energy provide almost 10 percent of total generation in the US in 2019

Photo, posted April 8, 2019, courtesy of City of St. Pete via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Economic Inequality

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A new study by Stanford University looked at the effects of climate change on global economic inequality.  The study found that the gap between the economic output of the world’s richest and poorest countries is larger today than it would have been without global warming.

The warming climate has enriched cooler countries like Norway and Sweden while dragging down economic growth in warm countries such as India and Nigeria.  The results of the study showed that most of the poorest countries on Earth are considerably poorer than they would have been in the absence of rising temperatures.  At the same time, the majority of rich countries are richer than they would have otherwise been.

Detailed analysis of 50 years of annual temperature and GDP measurements for 165 countries demonstrated that growth during warmer than average years has accelerated in cool nations and slowed in warm nations.  Historical data clearly show that crops are more productive, people are healthier, and they are more productive at work when temperatures are neither too hot nor too cold.  That means that in cold countries, a little bit of warming can help but the opposite is true in places that are already hot.

For most counties, whether global warming has helped or hurt economic growth is pretty certain.  Tropical countries in particular tend to have temperatures far outside the ideal for economic growth and they are already among the poorest countries.  It is less clear how warming has influenced growth in countries in the middle latitudes, such as here in the United States.  Some of the largest economies are near the perfect temperature for economic output but continued warming in the future is likely to push them away from the temperature optimum.

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Climate change has worsened global economic inequality

Photo, posted November 1, 2011, courtesy of CIAT via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Renewables Without Storage In Texas

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Texas has a Texas-sized appetite for electricity and relies most heavily on natural gas, coal and nuclear power to get it.  But in recent times, wind power has grown tremendously in the Lone Star State and it has already leapfrogged past nuclear power.  Coal could be the next domino to fall.

In the past few years, solar power has become competitive with wind in terms of price.  Texas is a large, coastal state in the sunny southwestern U.S. and has significant solar resources.  As a result, the amount of solar power in Texas is now growing rapidly.

In order for a combination of solar and wind power to address the bulk of electricity demand in Texas, there needs to be a way to provide reliability that these intermittent sources don’t necessarily provide.  Energy storage is a solution that ultimately is likely to be part of most electricity grids, but currently it is still expensive on a utility scale.

A new study from Rice University looked at the complementarity of solar and wind power in Texas.  Complementarity refers to balancing the output of solar and wind systems.  The peak performance of wind and solar occurs at very different times in different regions of the state.  The study suggests that the right mix of solar and wind systems in the right parts of Texas could provide a continuously reliable energy system.  On both a yearly and daily basis, wind and solar power resources in Texas complement each other in terms of peak performance.  It is a matter of locating the solar power and wind farms in the right places.

With the Texas solar industry really starting to boom, there is a real opportunity to integrate far more renewable energy into the Texas grid.

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More Renewables with Less Energy Storage: Texas Shows How

Photo, posted June 8, 2018, courtesy of Laura Lee Dooley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Battery That Eats Carbon Dioxide

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Fossil fuel-based power plants are increasingly considering the use of carbon capture technologies as a way to reduce emissions.  The biggest challenge to the wide-spread adoption of such technology is its energy cost, which of course equates to economic cost.  Present-day power plants equipped with carbon capture systems can use up to 30% of the electricity they generate just to power the capture, release, and storage of carbon dioxide.

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Geothermal Power For LA

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Los Angeles has a tremendous thirst for electric power and is always trying to find new sources.  On December 1, the Los Angeles Department of Water and Power began buying all the power generated by the brand-new 24 MW Tungsten Mountain geothermal power plant located in Churchill County in Nevada’s Great Basin region.

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