Tag Archives: PV electric

Energy Plus Agriculture

All human endeavors have some impact on the environment be it good, bad, or otherwise. This is especially true when it come to power production. Relatively cheap and available power has transformed the human landscape. Life expectancy more than doubled since the advent of the industrial revolution begun late in the 18th century. The cheap power aided agriculture by greatly increasing productivity and reducing the threat of starvation. Less demand for agricultural labor freed the attention of others to expand an understanding of health care.

However, the negative impacts of the utilization of fossil fuels – coal, oil, and gas – are legendary. In December, 1952 a combination of weather conditions and pollutants from coal smoke killed thousands of Londoners. Oil slicks on the Cuyahoga River in Cleveland, Ohio frequently caught on fire throughout the 1960s. Re-injection of fracking wastes from the production of natural gas has been blamed for recent earthquakes. And then there is global warming and climate change which threaten the planet.

So, power is good, but power from fossil fuels is not so good. The obvious answer is power without the negative impacts imposed by fossil fuels. All the alternatives have some negative impacts but in aggregate, are an improvement.

An interesting combination of technologies is referred to as agrivoltaics, the pairing of agriculture with solar panels to increase farm income. The results from studies here in the United States and Australia are quite surprising.

At first blush one would think that putting solar panels on a pasture would produce energy from the solar panels but the shading would decrease forage production. A study in Australia found just the opposite. Properly spaced and elevated solar panels actually increased forage production. Partial shading was not a significant issue, but the presence of the solar panels reduced loss of soil moisture.

At the same time that the panels help agriculture, agriculture helps the panels. Transpiration of the biomass under the panels lowered the temperature around the panels and increased solar electric output.

An unanticipated benefit was found in a study in Oregon. Panels installed on a pasture on a sheep farm greatly reduced predation of lambs by eagles. The panels provided shelter from eagle strikes.

In a related vein, the marriage of solar panels and water bodies is synergistic. In arid lands evaporation from a reservoir is significant issue. Placing solar panels on pontoons close to the water’s surface reduces evaporation and as before, the cooling effect of the water increases energy production.

Even without the benefit of increased energy production, solar panels can be beneficial. Rooftop systems reduce exposure of homes to harsh weather. Or how about decking over asphalt parking lots? The shade provided will help cool the lot and at the same time provide electrical energy to perhaps charge electric vehicles while the owners shop.

With forethought, energy production from solar panels can be enhanced and simultaneously provide beneficial effects to land use.

Dr. Bob Allen is Emeritus Professor of Chemistry, Arkansas Tech University.

Energy Storage Efficiency

There are those who constantly dismiss wind and especially solar as impractical energy sources because it is not available all the time, hence standby power must be available – fair enough. Right now Unit One of Arkansas Nuclear One is offline for refueling.

So is anybody sitting in the dark for a month or two? Of course not. Must there be another nuclear reactor standing idle waiting for Unit One to go down for refueling? Again the answer is no. There is sufficient excess capacity in our electrical grid to make up the difference in electrical energy needs during the outage. The same is true today for our intermittent energy sources, wind and solar. It is estimated that no additional backup will be needed until we reach about thirty percent contribution of these renewable sources to our total electric production.

Right now wind turbines to our west and the solar panels at my home use the grid as storage, just like Unit One. When the wind isn’t blowing, the sun isn’t shining, or Unit one is offline to refuel, the other power sources in the grid make up the shortfall. Electrical energy transmission and storage are hot research topics in science and technology. Numerous ways exist already for grid-scale energy storage, the ongoing research is to find ways to store energy efficiently and affordably.

One option being explored by as Swiss company is a cuckoo clock writ large. Excess energy is used to raise concrete blocks up, just like the weights on a clock. To recover the stored energy simply allow the weight to go down, turning a generator as they come down. This type of energy storage is not very efficient, maybe sixty to seventy percent, but is inexpensive.


At the other end of the spectrum is a high-cost, high-efficiency strategy such as a rechargeable Lithium-ion battery. The efficiency here is about ninety percent. Although expensive, Lithium-ion batteries are quite lightweight so they have value to power portable devices, from hearing aids to electric cars.

One energy storage medium that most don’t recognize as such is Hydrogen. Hydrogen gas is very energy-dense, meaning a small amount of it will store a lot of energy. Hydrogen can be generated by electrolysis of water. The hydrogen can be stored until energy is needed, then the hydrogen can be burned to make steam to turn a turbine to generate electricity. But, burning anything to produce heat to turn a turbine is a quite inefficient process. Because of the laws of thermodynamics, you can only get back about a third of the energy put in.

Better than burning to make heat is another technology known as a fuel cell. Fuel cells convert Hydrogen back to water without as much waste heat. Hydrogen generation via electrolysis, then conversion back to electricity has a “round-trip” efficiency of about fifty percent.

The science and technology of grid-scale electrical energy storage will mature as we expand our reliance on wind and solar, ultimately eliminating the use of fossil fuels.

Dr. Bob Allen is Emeritus Professor of Chemistry, Arkansas Tech University.

The Green New Deal

The Green New Deal is a proposal to address global warming and economic inequality. It is widely feared by conservatives as a proposal designed to take away freedom – and cars and money and hamburgers and airplanes. Nonsense.
What it is is a very broad brush plan to eliminate the use of fossil fuels and the release of other greenhouse gases in ten years. Although the timeline is unreasonable, the objective of necessity will be accomplished in the longer term.
Under the plan, sustainable energy sources will be expanded to eliminate the use of fossil fuels for electricity production. Wind and solar with battery backing can eliminate the need for any fossil fuel use for electricity production. This is already underway, as the use of coal has been cut in half in just the last two to three decades.
At the same time, grid-scale batteries are becoming a thing. The City of Fayetteville will soon begin utilizing a ten megawatt solar panel system with energy storage in batteries – intermittency is not an issue with battery backup. Entergy is planning to close two coal fired plants and is building its own solar farms.
In our economy, the transportation sector is the largest user of fossil fuels. Electrification of transportation is in its infancy but happening none the less. Tesla, the biggest manufacturer of electric cars, has sold over a half-million vehicles since they began in 2012. Electric long haul trucks, semis, are in development and will hit the highways in 2020. Electrification of the rails is a no-brainer, it exists already on a limited scale and can be expanded nation-wide.
A tougher nut is aviation. Jet fuel, essentially kerosene made from crude oil, is an ideal energy source as it is very energy dense. To eliminate the use of fossil fuels from aviation will require either of a couple of solutions. The most likely, especially in the short term is to manufacture fuel synthetically from renewable sources.
Biodiesel from oil crops like soybeans is a possibility but would compete with cropland for food production. Better would be the use of waste organic matter as a feedstock for fuel production. This is already happening but needs to be done more efficiently.
Electrification of aviation has already been achieved but is a long way from commercial airlines’ scale. A battery-powered single engine plane with a range of four hundred miles has been flown in England.
The cost of the total conversion to sustainable energy systems will require considerable investment in research and infrastructure, but at the same time it will create quality jobs in an increasingly automated economy. The increased tax revenues from these new jobs can offset some of the costs.
Then there is the issue of what is the cost of doing nothing. Hurricanes in the East, flooding in the Midwest, and wildfires in the West are already costing hundreds of billions of dollars a year and will only get worse from inaction. Our future depends on facing the reality of climate change. The sooner we address the issue the less costly it will be.

Favoring the Sun

Polling shows that a clear majority of Arkansans, 60 to 70 percent give or take, recognize that global warming is happening. Without any polling data, we can only guess the everybody given a choice would favor clean air over polluted air. One method to reduce the rate of global warming and clean the air is to generate electricity from solar panels. Keeping the lights on in a house at night or through a week or two of wintery overcast requires one of two options, a battery bank or buying power from a utility during those periods.

The latter is by far the most common as batteries, where utility power is available, are far more expensive. A common solution is a so-called grid-tied array. People with rooftop solar panels remain connected to the utility grid so that they can get power at night. During the day they can generate the power they need from the sun. To make solar power more attractive most states have some form of net metering.

Net metering is achieved via a bi-directional meter. At night when solar panels are inactive, the meter runs normally, but during sunny periods when the solar panels produce more power than is consumed in the home, the meter runs backward. The homeowner is at these times a net producer, essentially a little power company selling to the utility.

Act 464, 2019 addresses some issues with solar energy production. It allows for third-party leasing. Essentially this allows a homeowner to rent his roof space to another company for placement of solar panels. It also allows for larger net metered arrays so a business can take advantage of the sun to power their facility. A debate exists as to how the solar panel owner is rewarded for their excess production. The simplest and current method in Arkansas is that excess production is rewarded at the same rate as consumption. If in a given billing cycle there is an excess production, credit for that production is carried forward.

Utility executives say that this makes them buy power at a retail rate. Of course, they want to buy power at a wholesale rate, then sell at a retail rate to maintain profitability. But that is an oversimplification. Utilities pay different rates for power depending on demand, so there is no single wholesale rate. High demand times calls for the purchase of expensive “peaking” power. Conversely during low demand times equipment is idled which also has a cost.

Power demands vary by both season and time of day, but one thing is clear. Demand for electricity is always higher during the day than at night. Wouldn’t it be neat if there were a way of producing power during the day when it is needed but not at night so no utility equipment is idled? Solar generated electricity is nicely matched to demand which can serve to lower overall costs to the utility and at the same time clean the air and slow global warming.

The act has good and bad points, but overall it is supported by several environmental organizations.

Dr. Bob Allen, Ph.D., is Emeritus Professor of Chemistry, Arkansas Tech University.

Intermittency Need Not Be a Problem

There is no question that the future of power will be from the sun. Wind generation and solar panels are the predominant contenders. The president has wrongheadedly bragged about bringing back coal as an energy source. It hasn’t nor will it happen for simple economic reasons. Natural gas generation of electricity is cheaper and wind and solar are rapidly approaching parity in cost. Burning coal has the additional unaccounted burden of fouling our air and water.

The only advantage that fossil fuels have is that once extracted, they are available for power production near continuously. Sustainable sources such as wind and solar are available only intermittently. The relative availability is referred to capacity factor (CF), the fraction of time when a power source is available. Generally fossil fuel consuming power sources have higher capacity factors than intermittent sustainable sources, but are by no means constant.

The point of this is that all our electric generation sources are intermittent to a degree but power demands are continuous. At times less power is needed such as at night, or during the spring and fall when less heating or cooling is needed. Interconnected grid systems match power production and demand by balancing the various sources. Sustainability experts estimate that we can introduce intermittent power sources into the gird up to about 30 % of our total production without changing anything. After that we will need to add storage or change the way we utilize available intermittent power production.

Most think of batteries when considering electricity storage, but it is not the electricity necessarily that needs to be stored but rather the potential. Pumped storage is an example of the latter. In several locations, excess power at night can be used to pump water up a hill into a storage reservoir. During the day when demand increases water can be released to generate power.

Another strategy is to match jobs and/or lifestyle to the availability of electrical power just like we do for other traditional activities. We don’t grow corn and beans in the winter. We don’t go downhill skiing in the summer. In some locales power consumption is managed on a small scale with time of day pricing of electricity. Generally there is less demand for electricity at night, so power companies lower the price at night. This influences people to shift power consuming activities to later hours.

Larger scale operations could be shifted to times when energy is more available. The upper midwest has abundant wind energy available. It is available intermittently but predictably. Manufacturing schedules could be matched with the availability of lower cost power.

Solar power could easily be matched with power needs which themselves are only intermittent. Huckleberry Creek north of Russellville, Arkansas is a 500 acre man-made impoundment. It provides drinking water and in most years is sufficient. On occasion water is pumped from the Illinois Bayou uphill into the impoundment. Pontoon mounted solar panels could be floated on the lake to provide pumping power. There are a couple additional advantages here. Evaporation would be reduced by panel coverage and the solar panels themselves would be more efficient due to cooling from the water.

Scalability in Energy Production.

Scalability is the capacity to expand production as the need for additional power comes to the fore. A nuclear power plant can take years from the time of initial planning, permitting, and construction, whereas installation of solar panels for a home array will take only a couple of days. The material and labor costs during the construction or installation phase raise the cost of the power source over the cost to fuel and operate the facility once completed.

For necessarily large projects like nuclear or hydro-power facilities, long lead times are needed to bring power on line. This means that planning and construction must begin long before the power is available. This has considerable monetary cost because money is spent year after year before any money comes in from the sale of the power after completion.

An unpredictable risk inherent in the long term, big projects is that conditions may change. A steep drop in the economy during the recent “great recession” resulted in decreases in demand for energy world wide. Changes in technology, particularly with power sources which are more scalable may make a large project obsolete. Natural gas turbine technology is quite scalable. Turbines designed for jet aircraft can be used to generate electricity. The advent of directional drilling and fracking has greatly increased the availability and lowered the cost of natural gas which fuels scalable gas turbine facilities. Planning and construction of large scale coal plants are being canceled left and right.

Our economy is slowly recovering from the recession and new power sources are needed. Scalable power supplies are rapidly replacing large projects because they can reliably deliver power when and where it is needed and at a lower cost.

Solar power is booming across the country. Solar PV is growing 17 times as fast as the economy as a whole. This is due in large part to its scalability. If you need a little power, use just a few panels, such as what be need to charge the batteries on a remote cabin or an RV. To power the average home requires about 20 or 30 panels (10 kilowatt system which can produces 1100 kWh per month.)

For utility scale solar the numbers can get quite large. A one megawatt facility in Benton AR just went online. It employs 3,840 panels on a 5 acre site. The largest planned in Arkansas is an 81 MW, 500 acre facility with 350,000 panels. The country’s largest array not surprisingly is in California. At 550 MW, the array of over 2 million panels will power close to 100 million homes.

Wind is similarly scalable except at the lowest end of the spectrum. Modern wind turbines for utility scale facilities are 2 MW, however 8 MW turbines are being used in offshore locations. For perspective an average nuclear reactor is 1000 MW. Wind farms in the midwest vary in size but average around 200 turbines. A wind farm of this size could cover 50 square miles, but the actual footprint is minuscule as the land within the farm can still be used for forage/pasture.

Trump Pulls Out

It is now clear now that the current administration has withdrawn from the Paris Agreement for specious reasons. Trump will take us off the world stage, away from 195 countries who do recognize the risks of ignoring global warming, ocean acidification, and climate change.

Global warming as a concept is not new. Svante Arrhenius, a Swedish chemist and Nobel laureate wrote in 1896 on the risks of continued burning of fossil fuels and the resultant accumulation of Carbon Dioxide (CO2)in the atmosphere. [On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground] The concentration of CO2 in the atmosphere had been stable stable for hundreds of thousands of years – under 300 parts per million (PPM). In under 200 years we have raised the concentration to the current value of over 400 PPM, 150% of the value at the start of the industrial revolution.

Despite the relatively simple physical principals involved and despite the evidence from air and water temperatures, rising sea levels, and melting ice President Trump still thinks that global warming is a hoax. He seems fixated on the idea that developing sustainable energy supplies will drag our economy down. Is there evidence of such?

Very simply -No. Germany has installed more solar photovoltaic energy systems per capita than any other country, yet they are running a trade surplus with the United States. On a good day Denmark can produce 100 % of its energy from wind turbines and runs a considerable trade surplus with the United States. Ironically, much of their surplus involves selling wind turbine technology to us. We do have a small industry manufacturing wind turbine blades, but the company is Danish. China has leapt to the head of the pack for producing solar panels and we all know about their trade imbalance.

What do the captains of industry here think? Big fossil fuel producers such as Exxon-Mobil support the agreement. Even coal companies support the agreement. Walmart supports the agreement. Of course forward looking companies like Alphabet, the parent company of Google, Apple, Tesla support the agreement. Polls shows that the majority of Americans in every state, across the political spectrum support the agreement.

The agreement that we are walking away from is first and foremost voluntary. The agreement would in no way allow foreign influence of our laws or sovereignty. The agreement calls for international goals for reducing the rate of global warming by reducing the release of CO2 and other greenhouse gasses.

The US goal was a reduction of greenhouse gas emissions by 27 % of 2005 emissions by 2025. This is doable with a combination of energy efficiency, sustainable technologies such as wind and solar and switching from carbon intensive coal to natural gas. These changes to our economy are already underway and by participating in the agreement we show the world that we care about collective actions for all humanity, even for all life on this planet.

By not joining the agreement we turn away from 195 countries and join with Syria, torn by a violent civil war, and Nicaragua, who thinks the agreement doesn’t go far enough.

Booming Solar

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Sustainable energy is currently the most rapidly expanding form of energy in the United States. The same is true here in Arkansas. Whereas we are not well set for wind as our neighbors are to the west, solar panels (PV) that generate electricity are effective, and getting cheaper by the day. Solar arrays now cost less than half of what they cost just 10 years ago.

The price is now so low as to be competitive with more conventional power sources such as coal and natural gas, and infinitely cleaner. Current solar capacity (as of 2015) is 20.1 megawatts (MW.) This is an unbelievable 640 % increase over all PV power installed up through 2014. The new power installed in 2015 is dominated by utility scale power, 15.4 MW. Commercial industries and businesses installed 0.24 MW and the residential sector 0.46 MW. This represents a 56 million dollar investment in clean energy and jobs.

Solar power has come of age, not just for people wanting a little power for an off-grid cabin in the woods, but residents tied to the grid, industries, and especially power companies. One real advantage of solar power is its scalability. If a power company needs to expand their energy supply a small amount, they can add a small solar field. If they need a lot of power, they install a bigger field. No alternative has this scalability. You just can’t build a (cost effective) small coal or nuclear plant. Not even natural gas fired turbines are as scalable.

The L’Oreal plant in North Little Rock will install several thousand PV panels, about 1 MW’s worth. In March 2016 a private-public consortium consisting of two Arkansas Electric Cooperative Corporations, and Aerojet Rocketdyne will install a 12 MW solar field near East Camden. The largest install this year will be an 81 MW solar farm to be installed by Entergy near Stuttgart.

Generally installs of home solar arrays are booming also. Most cost effective for the consumer is a grid-tied net metered array. This system allows the home owner to remain connected to the grid in addition to the solar panels. When the sun shines the panels provide energy to the house, but when the sun is not shining, the home can draw power from the grid just like any other home.

PV systems can be sized to provide all or any fraction of the power needed for the home. If a particular array actually produces more energy than can be consumed in a given month, the law allows the excess to be carried over to a month when energy is needed.

The consumers gain is however the power companies loss, and they don’t like it. They lose profits by not selling as much electricity and even worse net metering threatens the vertically integrated structure of the business. They are the power generators, the wholesalers, the distributors and the retailers, and they want to keep it that way. Other states, notably Arizona and Oklahoma, have instituted additional fees for home solar which will severely limit the development of truly distributed clean energy.

The Public Service Commission here in Arkansas is empowered by law to set rates and rate structures of electric utilities. Over the next year they will be conducting studies to determine if changes are needed (read additional costs to home solar users.) The utilities will be arguing that they have to claw back their profits to remain in business. Stay tuned.

Go Solar

The amount of solar energy available to the United States is overwhelming. With today’s Photovoltaic technology, 16 per cent efficient PV panels, the total energy needs of the country could be met using a land area of only 8,000 square miles. This is an incredibly small area compared to the 3.8 million square miles of total land area. All the solar panels we need to power the country could fit in a fraction of Elko County in Northeast Nevada.

Just imagine, miners don’t need to die underground to extract coal. Mountain tops don’t need to be blown off and pushed into valleys to get at a coal seam. We wouldn’t need to worry about whether fracking wastes pollute our ground water, or bust up the foundations of homes to access natural gas. We don’t need parking lots full of high level radioactive waste from nuclear power plants. Yes, you read that right. Our only plan for the storage of high level radioactive wastes, hot for tens of thousands of years, is to store the waste in concrete containers around the sites of nuclear plants.

The health of the public would be improved and incidentally the cost of healthcare lowered as we no longer would have have all the untoward things in the air that cause problems. Not burning any fossil fuels means less lung irritants such as fine particulates. Less heavy metals that cause nerve damage, less acid rain, less ozone, and the list goes on and on.

Rather than produce all the energy in a fraction of one county in Nevada, we could spread it out to the individual states. The US uses a total of about 4 trillion kWh per year. Closer to home, Arkansas uses about 50 billion kWh per year. To meet that need we would only use about 100 square miles, less than a tenth of the area of Arkansas County in the southeast part of the state. Or let’s make each county generate their share. For Pope County we need a scant 2 square miles out of 831. It’s easy to see that we have plenty of free, sustainable sunlight and the land foot print needed is not even an issue. We will also need to upgrade our transmission network, but still that’s doable. The real fly in the ointment is storage.

The aforementioned calculations of land area needed are for full power, 24/7 year around, assuming we have storage for when the sun doesn’t shine due to time of day, season or weather. This a problem but not an insurmountable one. Elon Musk, the manufacturer of the Tesla electric car, and Space X reusable rockets is building a huge battery factory in Sparks, Nevada. The battery factory will occupy a building covering an area equal to 95 football fields.

The factory will be powered exclusively by solar electric power, with energy to spare. The batteries built in this factory are lithium based and are intended for his fleet of electric cars, but it shows that really large scale production of all aspects of sustainable energy are not just something in the distant future but are close at hand.

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Alternative Energy Alternatives

So you want to be green, or at least greener, when it comes to your electricity use. There are a welter of options available. Here in Arkansas we are not blessed with sufficient wind resources to make homeowner wind very cost effective, so going green means solar photovoltaic systems (solar PV) are the best game going. But with this restriction there are still several different approaches to decarbonize your electricity.

In remote areas without grid connections, the only reasonable green electricity is with a solar PV system and batteries. The batteries are necessary not only to tide you over for when the sun doesn’t shine but also to stabilize the power to your home or cabin. Imagine on an otherwise sunny day a solar array is providing nicely for the home, but a cloud passes over. This would temporarily reduce the current, possibly to the point of damaging electronics, Hence batteries are essential. Just how many batteries needed is a function of how long will the sun not keep up with demand. On occasion in this area we can go for a week or two without much sun due to rain and clouds. The point is that this is the most expensive option due to the costs associated with the batteries.

Much more practical are so called “grid tied” solar arrays which essentially use the electrical grid as a battery. If you buy electricity from Entergy, SWEPCO, or AVEC for example, and you add solar panels to your home, the power company is your battery. When the sun shines your meter will slow down or actually run backwards sending power to the grid. At night or on rainy or cloudy days power is drawn back from the grid. Because Arkansas is a net metering state, when producing you are paid the same price as when you buy. Depending on how many panels you have you can replace some or all of your electrical needs. Currently costs are such that the payback period is about half the rated lifetime of the panels. You will recoup your initial investment in about a dozen years, and the panels will continue to produce for at least that many years to come.

All homes don’t have access to the southern sky on their property due to shading from trees or the terrain. That said you can still participate via community solar farms. The first community solar farm has begun near Little Rock. A developer is constructing a solar farm tied to Entergy’s grid. Any Entergy customer can basically buy a piece of the solar production. The buyer has their own meter which is aggregated with their home meter, just as if the solar panels were on their roof. Entergy deducts any power costs produced by the solar panels from the power costs at the home. The cost for this approach is somewhat higher as because of the costs for site development and land acquisition.

Yet one more option exists to green up your electricity. The green power costs for the aforementioned approaches all require some significant start up costs. Another alternative is to buy “green tickets” or participate in the purchase of Renewable Energy Credits. There are companies that will for a nominal charge on top of your actual electric bill, buy green energy. The additional charge is used to buy power from green sources and send that electricity to the grid, which offsets electricity from fossil fueled sources. Basically you are subsidizing clean energy. You don’t own any equipment but your dollars go to green the environment.