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A Possible Storage Breakthrough: Solar Energy | Earth Wise

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Solar energy is a nearly unlimited resource, but it is only available to us when the sun is shining.  For solar power to provide for the majority of our energy needs, there needs to be a way to capture the energy from the sun, store it, and release it when we need it.  There are many approaches to storing solar energy, but so far none have provided an ideal solution.

Scientists at the Chalmers Institute of Technology in Sweden have developed a way to harness solar energy and keep it in reserve so it can be released on demand in the form of heat—even decades after it was captured. Their solution combines several innovations, including an energy-trapping molecule, a storage system, and an energy-storing laminate for windows and textiles.

The energy-trapping molecule is made up of carbon, hydrogen, and nitrogen.  When hit by sunlight, the molecule captures the sun’s energy and holds on to it until it is released as heat by a catalyst.  The specialized storage unit is claimed to be able to store energy for decades.  The transparent coating that the team developed also collects solar energy and releases heat.  Using it would reduce the amount of electricity required for heating buildings.

So far, the team has concentrated on producing heat from stored solar energy.  It is unclear whether the technology can be adapted to produce electricity, which would be even more valuable.  In any event, the team does not yet have precise cost estimates for its technology, but there are no rare or expensive elements required, so the economics seem promising.  There is much more work to be done, but this could be a very important technology for the world’s energy systems.

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An Energy Breakthrough Could Store Solar Power for Decades

Photo courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Solar And Wind Energy And Groundwater

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The use of both solar and wind farms has been expanding all over the country as a way of lowering carbon emissions from the electric power sector.   According to a new study led by Princeton University, these renewable energy sources have another important benefit:  they keep more water in the ground.

The study focused on drought-prone California where both solar and wind power have been expanding dramatically.  California is the largest agricultural producer in the United States and has also experienced one of the most severe droughts on record between 2012 and 2017.

The study determined that increased solar and wind energy can reduce the reliance on hydropower, especially during times of drought. 

The study looked at multiple scenarios in order to determine how much solar and wind energy should be used to maximize economic revenue and to see how solar and wind power could ensure groundwater recovery.  They created a framework to quantify the optimal pathways for maximizing hydroelectricity and agricultural income while avoiding groundwater depletion.

During the long drought, California’s agriculture industry relied heavily on tapping into groundwater stores, which is an unsustainable practice.  With more droughts likely to occur in California as well as increasing water demand from the growing California population, the burden on the state’s groundwater supply will only grow.

According to the researchers, it is far more practical to impose further regulations on groundwater use if sufficient solar and wind power is deployed.   They caution that these resources need to be deployed long before groundwater aquifers are depleted, or it will be too late for them to do any good.

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Solar and Wind Energy Preserve Groundwater for Drought, Agriculture

Photo, posted December 11, 2014, courtesy of Tony Webster via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Agrivoltaics

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A new study by Oregon State University has found that the most productive places on Earth for solar power are farmlands.   In fact, if less than 1% of agricultural land was converted to solar panels, it would be sufficient to fulfill global electricity demand.

The concept of co-developing the same area of land for both solar photovoltaic power and conventional agriculture is known as agrivoltaics.

The synergy between agriculture and solar power is not surprising.   People have been growing crops around the planet for at least 8,000 years and, long ago, farmers found the best places to grow them which turn out to also the best places to harvest solar energy.  The needs for solar panels are pretty similar to those of food crops.  The efficiency of the panels decreases if they get too hot.  Barren land is hotter than cropland, so the productivity of solar panels is less in such places.

The Oregon State Study analyzed power production data collected by Tesla, which had installed five large grid-tied, ground-mounted solar electric arrays owned by Oregon State.  The researchers monitored air temperature, relative humidity, wind speed, wind direction, soil moisture, and incoming solar energy.  With the data, they developed a model for the best conditions for solar panel productivity and they coincide with excellent conditions for agriculture.  Solar panels are kind of like people with regard to the weather:  they are happier when it is cool and breezy and dry.

Previously-published research shows that solar panels actually increase crop yields on pasture or agricultural fields.

These new results have implications for the current practice of constructing large solar arrays in deserts.  Agricultural lands may be a much better option for both solar production and crop production.

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Installing solar panels on agricultural lands maximizes their efficiency, new study shows

Photo, posted April 20, 2011, courtesy of U.S. Department of Agriculture via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Complications For New York Solar Farms

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A study by engineers at Cornell University looked at the implications of adding utility-scale solar farms throughout New York State.  Adding such farms could reduce demand for electricity from conventional sources by nearly 10% in some places.  But the engineers caution that winters in upstate New York could create some novel problems for the state’s power system.

Electrical energy demand tends to be low around midday when many people are not home.  Electrical production from solar farms is high at that time when the sun is at its highest position in the sky.  This can lead to what power system operators call “ramping”, which is the term for rapid increases or decreases in demand.

This sort of ramping was first discussed in California years ago.  When people wake up and prepare for the day, there is a morning peak in electrical load, which occurs before solar production ramps up.   When people get home from work in the evening, energy demands create a second peak.  A graph of this lack of synchronicity of load and supply looks a little like the shape of a duck and is popularly known as the duck curve.

The Cornell engineers figured out that maximum ramping in New York – where electrical demand and electricity supply from solar farms are out of synch- will take place in the winter.  In fact, when there are several days of sunshine in a row during winter, the largest ramping in the New York power system will take place.

The general issue of having solar energy available when it is most needed is one that is the driver for energy storage technology. If the energy can be provided when demand calls for it, there would be no more ramping.

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Winter could pose solar farm ‘ramping’ snag for power grid

Photo, posted September 8, 2015, courtesy of New York National Guard via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sunlight As A Cash Crop

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It isn’t so easy to be a farmer these days.  Farming has always involved long hours, hard work and the uncertainties of weather and yield.  The 21st Century has added new and unique challenges such as increasingly unpredictable weather, insect infestation and disease, and low commodity prices.  Add in sudden tariffs and farmers struggle even more to make ends meet.  The default rate for farmers’ loans is the the highest in at least nine years.

One thing that remains reliable for farmers is the sun.  It rises in the morning and goes down at night.  The sun can be trusted, unlike politicians, rain, or commodity prices.  These days, many farmers are taking advantage of the dependability of the sun to make money from a new cash crop: solar energy.

The trend is spreading.  North Carolina has been a leading solar energy state for several years and a 2017 report found that solar energy generates 30% of the income of many farms.  Typical annual rent payments for farmland by solar companies range from $500 to $1,400 per acre in North Carolina.

A growing list of states have clean energy mandates targeting 100% use of renewable energy.   These mandates provide incentives for farmers that make installing solar a financially smart decision and falling prices for solar installations make it an even better deal.

Solar works well when co-located on a farm and can be built in ways that minimizes impact.  It is quiet, uses almost no water, doesn’t pollute, and if it is decommissioned, the land can go back to its previous use.  If the solar facilities are raised up, the same land can be used to graze livestock or grow shade-tolerant crops.

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Harvesting the sun is the new cash crop

Photo, posted December 25, 2017, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shutting Down Minnesota Coal Plants

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One of the largest utilities in the United States, Xcel Energy Inc., announced that it will close its remaining coal-fired power plants in the Upper Midwest a decade ahead of its previously-announced schedule.  In addition, the company will add 3,000 megawatts of new solar capacity by 2030.

The Allen S. King plant in Oak Park Heights, Minnesota and the Sherburne County Generating Station in Becker, Minnesota are the plants in question.  The transition away from coal is a difficult challenge for such small communities.  The plant in Becker, for example, employs 300 people in a town of 4,500 and provides 75% of the city’s tax base.  Towns like this realize that coal is inevitably going away and must find ways to move beyond their dependence upon it.  The Becker plant will not completely close until 2030, but parts will now only run seasonally, and one of the 3 units will close permanently in 2023

Xcel Energy, based in Minneapolis, serves more than 3.3 million electricity customers in 8 states.  Last December, the company announced that it would deliver 100% clean, carbon-free electricity by 2050 and would achieve an 80% carbon reduction from its 2005 levels by 2035.  It is the first major US utility to set such a goal.

Xcel will increase its investment in energy efficiency measures, bring 1,850 megawatts of new wind capacity online in Minnesota by 2022, and keep its Monticello Nuclear Generating Station operating until 2040, a decade later than planned.  The company’s stepped-up clean energy strategy is part of a new legal settlement between the company, environmental organizations, and labor groups that involves Xcel’s proposed $650 million purchase of a 760-megawatt natural gas plant.

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A Major U.S. Utility Is Closing Its Coal-Fired Power Plants a Decade Early

Photo, posted January 3, 2016, courtesy of Tony Webster via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fern-Inspired Energy Storage

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The amount of solar energy striking the surface of the earth in two hours is enough to supply all of humankind’s needs for an entire year.   For this reason, it is widely thought that solar energy should be our primary source of electricity.  If this is to happen, however, there must be cost-effective ways to obtain solar electricity regardless of the time of day, weather, or seasonal changes. Essentially, there must be ways to store the energy from the sun to use it when we need it.

[Read more…] about Fern-Inspired Energy Storage

Turning Sunlight into Fuel

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When looking at the best ways to meet humanity’s energy needs, there is little doubt that the sun is the ultimate answer.  In one hour, the Earth receives enough energy from the sun to meet all of our needs for a year.  Despite this fact, the world currently only gets about 1% of its energy directly from the sun.

[Read more…] about Turning Sunlight into Fuel

A Giant Solar Power Plant In India

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In late September, the world’s largest solar power plant went online in the Indian state of Tamil Nadu.   It is a 648 MW array of solar panels that is spread across 2,500 acres in the town of Kamuthi and will supply enough energy to power 300,000 homes.

[Read more…] about A Giant Solar Power Plant In India

One Million Roofs

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Sometime early in May, the United States installed its one millionth solar energy system.  Achieving this milestone took the solar industry about 40 years to accomplish.  Because of the phenomenal growth of solar power in this country, industry experts predict that it will only take two more years to reach the second million and there are predictions that by the year 2025, there will be one million new installations in the U.S. each year.

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Solar Power And Drinkable Water

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According to a report from the International Food Policy Research Institute, more than half the world’s population will be at risk of water shortages by 2050 if current trends continue.  As the climate continues to change, severe droughts are becoming increasingly commonplace.

[Read more…] about Solar Power And Drinkable Water

Mandatory Solar In San Francisco

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California leads the nation in the use of solar energy with well over half the country’s solar electric capacity. The state is the home of several of the largest thermal solar generating plants in the world and between those and multiple utility-scale photovoltaic plants, California utilities get more than 5% of their power from the sun.

[Read more…] about Mandatory Solar In San Francisco

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