Tag Archives: PV electric

Private Sector must be the Answer

In Al Gore’s award winning movie “An Inconvenient Truth” he used the old saw to depict a real problem with global warming. If you put a frog in hot water it will immediately jump out. Put a frog in cold water but very slowly warm it up and the frog will stay until it is too late and be boiled alive.

That is a nice analogy for the dilemma we face with with global warming. The process is slow. Another analogy would be to call it glacially slow, but glaciers are moving, and melting, at a fairly rapid pace these days. Humans and a number of animals evolved to react to rapidly occurring threats – the snap of a twig in the brush, the glint of light from an eye, and we are ready to fight or flee.

Global warming is a decades to centuries change that threatens us now, and many just don’t see the threat, a threat not to us individually, but to our future. Some are so insensitive to the risk that even if they believe it to be true, won’t react because it doesn’t matter to them personally. If the majority of us hold this opinion, we are doomed as a species.

Some governments are beginning to react with policies that favor carbon free energy strategies, but the steps are often small and can be more costly than simple business as usual burning of fossil fuels. Hey, it’s on face value cheaper and we know how it works.

On a more hopeful note is the fact that technology got us into this problem, but technology and the private sector, hold the potential to get us out. Obviously we need to stop burning fossil fuels, especially coal and oil. Natural Gas, essentially methane, is does not produce as much pollution as the others, but ultimately its use must be curtailed also.

There two ways to replace the fossil fuels, use less through efficiency and replace energy production with non-carbon sources such as wind, solar and geothermal. Of the three, wind is the most developed. We currently get about 4 % of our electric energy production from wind, entirely land based. The potential for off shore wind, especially on the east coast affords considerable potential but currently is more expensive to exploit than wind resources in the midwest. Currently the cost of wind generated power is as cheap as that from a modern coal fired plant. And the costs continue to decline, the opposite of the cost for producing power from coal.

Solar Photovoltaic systems (solar panels) are sprouting up everywhere, especially since the price has dropped by half in just the last few years. Not only are homeowners adding panels to their roofs but utility scale systems are being installed. Entergy recently announced that they intend to build a 500 acre solar farm near Stuttgart. For perspective, a square mile covers 640 acres.

Until the intermittent energy sources of wind and solar penetrate to about 30% of total production, no additional back up power is needed. Essentially there is enough existing reserve power to keep the lights on after dark when the wind isn’t blowing. Beyond that, battery backup will be needed. Development and deployment of utility scale battery production will surely follow the demand.

World Wide Wind

We will at some point cease to produce electrical energy by burning fossil fuels, either (sooner) because we realize the harmful effects of using the atmosphere as a toilet, or (later) because we simply use them all up. These fuels can be replaced with sustainable sources, principally wind and solar. Where are we now and where are we going?

In the United States we currently get 13 per cent of our electrical power from renewables. The majority of that from hydropower, followed by wind biomass and solar power as a distant fourth. There seems to be limited potential for growth in hydropower or biomass but the sky the limit for wind and solar, assuming that the issue of intermittency can be overcome.

Although we have no national policy for the country, president Obama has mandated that the federal government get 20% of its electrical energy from renewables by 2020. Various states have renewable portfolios that range from trivial to ambitious: The old south, a couple of coal states in the Appalachians, a few midwest to rocky mountain states have none. Hawaii has the most ambitious, with a target of 40% by 2030.

Internationally, it’s a mixed bag. Mountainous Costa Rica, with a population of about 5 million, gets from 90 to 100% of its electrical energy from renewables, mainly hydro and geothermal. Similarly Norway with twice the population of Costa Rica produces very close to 100% of their electric power from hydropower plants.

Because of availability of cheap electric power they have developed energy intensive industries such as the production high grade Silicon for solar cells. Interestingly a focus of World War II was on Norway. Germany invaded Norway to gain access to energy intensive production of heavy water for their experimental nuclear reactor program.

The real potential for expansion of renewable power is in the wind, especially in countries with lots of coastline. At one point last week, Denmark was producing 140 % of its electrical energy, exporting the excess to Sweden and Germany. Their current average wind produced electricity is approaching 40%, and they are still building out.

Germany is an interesting study. They have a vigorous low carbon energy transition plan (Energiewende.) Their target is an astounding 80% renewable by 2050! They are currently installing wind and solar PV faster than anybody on the planet. Currently they are around 27% with very little hydropower, twice the US average.

The biggest player of course is China. They are the current world leader in carbon emissions, having surpassed the US a few years ago. China’s air pollution problems are legendary. Smog from from eastern China can be tracked across the pacific to our west coast. They recognize they have a problem and are aggressively addressing it by moving away from fossil fuels and toward efficiency and renewables. In 2014 they installed three quarters of the new solar capacity on the planet.

tesla battery

Batteries for the Future – Now

A recent Op-Ed in the New York Times (about food) gave a hat tip to the Sierra Club and their Beyond Coal campaign – an effort to close all coal fired power plants by 2030. The point of the piece was the necessity of activism and organizing around a particular issue.

Since the inception of the program in 2010, no new coal plants have been built and 188 closed or planned to close in the near term. Currently just of under 40% of the electric generation capacity in the United States comes from burning coal, but the number is falling – replaced by natural gas plants and a mix of wind and solar.

As long as intermittent energy, wind and solar, constitute a small fraction of the total electric supply, grid operators can balance the load as needed by reducing power from the coal plants. But what about when the coal plants are gone? What do we do when the sun isn’t shining or the wind isn’t blowing?

There is no doubt that there is enough solar in the Southwestern US or wind the Midwest to power the nation, but storage and transmission is a controlling factor to the use of these clean sources of energy. Tea party types are resisting transmission lines on the basis of property rights and governments in conservative states are making small scale renewable energy less attractive to protect their power companies’ turf.

When one thinks of energy storage, explicitly electrical energy, batteries are it. Enter Elon Musk, billionaire entrepreneur and builder of the Tesla Electric car. More important than the electric car are the batteries that power them, at least that is what Mr. Musk thinks. He has recently gone into the battery market, not only for his cars, but for stationary applications. He introduced a 10 kWh battery that can be used for a myriad of applications.

For a home owner this means “behind the meter” storage. Obviously off the grid folks rely on batteries but even grid-tied homes can utilize storage for weathering storms when the grid goes down. Folks with grid-tied renewable energy systems can utilize storage. Some power companies have time of use metering, that is the cost of power varies as to when it is used. If a home owner has a storage capacity, S/he can chose to sell power back to the grid when the price is higher. Even without a renewable energy supply, home owners with storage can charge batteries during the night when rates are lower, then sell power back to the grid during the day, making a profit in the exchange.

Utility scale storage can be beneficial right now. Battery storage can be added incrementally to defer transmission and distribution line upgrades as demand grows. Batteries can be used to back up temporary shortages due to short term power plant outages. Not to get too far down in the weeds on these issues, suffice it to say the Batteries will play a huge part in the future of clean energy supplies.

This something we should all strive for. We will get away from burning stuff for power, and batteries will make this more practical.

earth

A Positive Potpourri

So much news about global warming and climate change is negative. The planet’s hotter, the weather weirder, and the future dimmer. Whereas over half of Americans believe in global warming, less than half care. But there is some hope for the future out there.

Little is coming out of congress but the state of California is leading the way to a sustainable future. The land of “fruits and nuts,” the land where the leader is referred to as “Governor Moonbeam,” will be breaking ground for a new high speed rail to run from San Jose to Los Angeles. The nation’s largest infrastructure project will cost billions but take scads of cars off the highways and planes from the sky. It will produce jobs that can’t be sent overseas, and most importantly reduce the carbon footprint for the people of California.

And speaking of a carbon footprint, Governor Jerry Brown has set an ambitious goal of 50 % of the energy to come from clean sustainable sources such as wind, solar and geothermal by 2030. Nowhere else in the country is there such an ambitious standard.

The Journal of Environmental Studies and Sciences show that the cost of onshore wind and solar PV are cheaper than coal for generating electricity, when the cost of climate forcing is factored into the use of fossil fuels, either gas or coal. The cost of solar panels alone has dropped by 50% between 2008 and 2009. Although Solar PV generated electricity only accounts of a scant 0.7 % of installed capacity, it recently has become the the most rapidly installed new generation in the country.

The oil and gas boom due to technological advances like shale fracking have accounted for a 10% reduction in oil imports (equivalent). That’s good but automotive efficiency due to gas mileage standards coupled with increase utilization of mass transit has resulted in nearly twice the savings, some 18% reduction. Reductions due to efficiency are far too often overlooked when considering reducing our reliance on fossil fuels.

An important aspect of sustainable energy is the fact that it creates jobs, more than any of the fossil fuel industries. The US Bureau of Labor Statistics estimates that there are about 80,000 jobs in the coal mining industry, but over a 142,00 jobs in solar industries.

Several HVDC transmissions are moving through regulatory approval, including the Plains and Clean Line which will pass through Pope county. When approved and constructed, they will allow the utilization of much otherwise stranded electric generating capacity from abundant midwestern wind.

Also here in Arkansas, a 12 megawatt (MW) solar photovoltaic installation will be built on a one hundred acre site in an industrial park in East Camden. Arkansas Electric Cooperative Corporation (AECC) will sell power to their members across Arkansas. AECC has also agreed to purchase an additional 150 MW for a total of 201 MW of wind power from producers in Oklahoma. An 80 MW wind turbine farm has been proposed for a site near Springdale. It will use a novel shrouded turbine design which is claimed to completely eliminate bird and bat mortality.

Energy Costs and Financing

It is difficult to compare the costs for energy from various sources, but it is an important issue. In Arkansas we are blessed with (or cursed by, depending on your point of view) relatively low electrical energy costs. We pay about eight to nine cents per kilowatt- hour (kWh) which is about three cents below the national average of twelve cents. In some locations and at some times of the day the costs can go over 25 cents per kWh. These costs do not include externalities such as damage to health and the environment, risks associated with global warming, political instability and direct subsidies to insure risky technologies.

It has been estimated that the inclusion of these costs could raise a monthly electric bill by two to five times. An average Arkansan’s electric bill would be closer to five hundred dollars rather than slightly over one hundred dollars per month.

Clean renewable energy from for example photo voltaic systems (PV, solar electric panels) can be prohibitively expensive when you compare the costs without consideration of the external costs of traditional electricity production. It would seem only fair then to subsidize PV systems and that is happening to a limited degree.

5.4 kW solar array

5.4 kW solar array

The federal government provides a thirty percent tax credit for residential and small commercial systems which makes these systems more competitive with traditional energy sources with their hidden subsidies. Recently the state of Arkansas through the Arkansas energy office has begun an additional subsidy based on energy produced by renewable energy systems. For program details see: http://arkansasenergy.org/.

The current program from the state provides for on-bill financing for qualified energy efficiency improvements that consumers can install on their premises: energy efficiency measures, distributed generation (e.g., solar photovoltaic, combined heat and power), and demand response (DR) technologies.

shade trees same energy

shade trees same energy

Consumers typically have extensive experience making utility bill payments, it is already a routine part of their lives. It is also conceptually attractive to make an investment where the energy savings that result are reflected in the same bill as the payments on the loan that funded the investment. This method of financing is particularly attractive for projects which have long pay back times. If the original owner sells the property, the financing remains with the improved property.

Low-E glass saves energy

Low-E glass saves energy

Because we have relatively low electric costs here in Arkansas, the payback for subsidized systems can be on the order of a couple of decades for large projects such as PV systems. In locations with much higher electric rates, say 25 cents per kWh, the payback would be much sooner.

The question then becomes, do you want to continue wars, and general global political instability because of our reliance on oil imports? Do you want to continue to support scraping the tops off of mountains to get at “cheap coal”. Do you want to continue to contribute to the degradation of the environment from oil spills? Do you want to contribute to the degradation of health through air pollution? To the deaths of miners and drillers? Global warming and ocean acidification?

You can walk away from all that now, but sustainable clean energy supplies are a future you can make happen now.  

 

Solar PhotoVoltaic Primer

The cost of photovoltaic systems (panels and inverter) has dropped to about 2 to 3 dollars per watt. At this price systems have payback times in the 10 to 15 year range, regardless of size. This assumes a cost of about 10 cents a kilowatt hour (kW-hr) for electricity.

Here are a number of nuts and bolts issues for those interested in solar power. First and foremost you must have a location with southern exposure. Even a small amount of shade can seriously reduce energy production. For most this means a roof top location, but it needn’t be if you have the space to put the array on the ground. The simplest mounting puts the panels flat on the roof. The pitch of the roof is not all that important as long as it faces south.

sun's path

sun’s path

The amount of space needed for an array of course varies as to how much total power you want to produce. Different manufacturers make panels in different sizes (watts) but the total space needed is the same because all PV panels have the same efficiency, about 15 %. Five 100 watt panels will take up the same space as one 500 watt panel. One kW requires about 80 square feet of space.

A big decision is whether the array is isolated or connected to the electrical grid. Grid-tied systems here in Arkansas can take advantage of net metering. This means that the power produced by the panels can actually make a meter run backwards if they are producing more power than the home is consuming at any time. About the only disadvantage of a grid-tied system is that when the line goes down, so does the solar power production. This is necessary to protect power line workers.

PV Grid-tied system

PV Grid-tied system

The alternative to grid-tied is to go entirely off line by buffering production with batteries. This avoids the aforementioned problem, but greatly increases the cost and “hassle factor” of the system. This is only practical when connection to the grid is cost prohibitive, as in remote locations.

The total amount of energy produced by a system is obtained by the total wattage of a system. For example a 1 kilowatt system can produce a maximum of one kilowatt hour only when the sun angle is ideal. Averaged over a year, a simple rule of thumb is that you can get 4 hours of net production per day. Hence a 1 kW system can be expected to produce 4 kW-hrs per day, more some days, less others.

Let’s use an average consumption of 1000 kW-hrs per month (close to the average in Arkansas) to determined a system sized to replace 100 % of electric needs. 1000 kW-hrs per month means 33 kw-hrs per day. Divide that by 4 to get a a little over 8 kW system. To allow for some inefficiencies say we use a 9 kW system. At 2.5 dollars a watt, the total cost would be 22,500 $. The 30% federal tax rebate brings the final cost down to 15,750 $. Sales taxes and installation will add to the cost, but these numbers can be used to approximate a cost if you are interested in going solar.

Energy Storage

The success of transitioning to sustainable energy supplies in the United States relies to a large degree on our ability to store energy produced by intermittent energy sources such as solar, wind and biomass. We have plenty sunlight and wind to go around. Conversion of biomass to a liquid or gaseous fuel is a convenient method for storing energy, but photosynthesis is quite inefficient compared to other ways of capturing solar energy. Also any biomass to energy scheme will involve burning something which always has some negative health consequences.

The future could be powered by electricity from solar and wind exclusively but how will we store the electricity for use when the sun isn’t shining or the wind isn’t blowing? Batteries are an obvious way of storing energy but are impractical for storing energy on the scale of an electric utility.

grid scale batteries

grid scale batteries

Batteries for powering transportation are in use now and will expand greatly in the future.

Most electric cars today use Lithium ion batteries. They have the best energy to volume and energy to weight ratios referred to as energy density. The problem is that even the best batteries pale in comparison to the energy density of gasoline. Liquid fossil fuels like diesel and gasoline are very energy dense and can produce 50 times as much energy as a Lithium ion battery of equal weight or volume. With current technology the Nissan Leaf, an all electric vehicle, has a range of under one hundred miles. Batteries being developed now can increase the energy density by five to ten fold, giving electric cars a range of several hundred miles.

Storing energy for the electrical grid can accommodate a wider range of methods. One of the simplest ways of storing energy is to pump water up a hill.

Pumped storage

Pumped storage

All you need are two reservoirs, one higher than the other. When energy is available it is used to pump the water to the upper reservoir. When energy is needed, the water is released, causing the turbines to reverse direction and generate rather than consume energy. The only limitation is space and geographic relief.

Another utility scale energy storage method being examined is compressed air. Just as pumping water up a hill stores energy, so does compressing a gas. In the latter part of the nineteenth century, several European cities used compressed air for energy storage. Rather than convert the energy in the compressed air to electricity, it was piped and metered to do mechanical work. Everything from motors for heavy industry to sewing machines ran on the compressed air. The major limitation of compressed air storage is the necessity of a large underground reservoir to hold the compressed air. Wind turbines in the midwest will in the future store energy with compressed air.

compressed air

compressed air

Flywheels are another method to store energy. An electric motor spins up the flywheel, later when energy is needed the motion is used to power a generator. The big advantage of flywheel storage is that it can be done anywhere. No need for a big hole in the ground or pairs of reservoirs at different altitudes.

One of the best methods to pair production and storage of energy is solar thermal. Simply heat a fluid with sunlight. When electrical energy is needed use the heat to power a generator. Power towers have a collection of mirrors pointed at the top of a tower. A fluid is circulated through the heated zone, then sent to a storage site for later extraction of energy.

All these techniques involve converting one form of energy to another, but can ultimately be used to generate electricity even when the wind isn’t blowing and sun isn’t shining.

large solar array

Solar Steel

People often think that solar photovoltaic panels are OK to put on a roof to cut ones electric bill a little but really doesn’t go far to fill the needs of the nation when it comes to electricity. Or that it’s OK for light weight usages like lighting in parking lots but can’t provide for heavy industries like steel mills. I would like to disabuse those folks of the idea that solar can’t keep us going.

First some fundamentals. Electrical energy is measured in Watt-hours (Wh) or multiples there of. If your monthly electric bill is about a hundred dollars, close to the Arkansas average, you are using a MegaWatt-hour (MWh), which is a million times a Watt-hour. This amount of electricity is available year around from a space about twenty seven feet on a side. It easily fits on a south facing roof. A system like this will not just lower your bill but eliminate it.

Let’s talk about power for heavy industry, and it doesn’t get much heavier than steel mills. Nucor Corporation operates twenty-three steel mills

electric arc furnace

electric arc furnace

across the United States producing twenty-two million tons of steel annually employing electric arc furnaces. If we can figure out how to do this with solar panels we can do anything.

It takes about one and a half Mwh electric to produce a ton of steel. On average each plant produces a million tons of steel a year, so we need one and a half TeraWatt-hours;

steel

steel

a TeraWatt is a million times a MegaWatt. How much land do we need per plant? It works out to one thousand five hundred acres. This is equal to the land use of less than four average farms in Arkansas. That’s it. The land occupied by four farms in Arkansas will provide enough sunlight to power a steel mill. Cool, huh?

When you look at total electric use in the United States over a year the numbers get really big. The national annual electric use is four PetaWatt-hours; a PetaWatt is a billion times a MegaWatt. So how much land would it take to generate all the electric power we use in the United States? A surprisingly small nine thousand square miles. This is an area smaller than Rhode Island.

The numbers I cite are good for the amount of sunlight in Arkansas using flat plate collectors. If the national power grid originated in Nevada using tracking panels, the area needed is less than five thousand square miles. There are counties in Nevada much larger than that. There is no question that sunlight alone can provide all the electric power we need in this country.

The obvious fly in the ointment is the need for storage when the sun doesn’t shine, or transmission to where the sun doesn’t shine, but both those limitations are under study and are an achievable goal in the near future. And that’s just solar Photovoltaics as an energy source. That amount of energy is available from wind turbines and the potential for geothermal is greater still.

pvbob

What about China?

There is a consensus among virtually all scientists that humans, by burning fossil fuels, are contributing to global warming and thus changing the climate. The climate has changed many times over the billions of years of earth’s existence, so what if we are changing it, why does it matter?

It matters because we are changing the climate on a timescale never seen before; hundreds, even thousands of times faster than any naturally occurring climate change. We are changing the climate at a rate which can cause massive extinctions as plants and animals fail to adapt.

The only viable solution is to stop burning fossil fuels. Coal, oil and natural gas represent carbon that was removed from the atmosphere over hundreds of millions of year. We are burning up these fuels at a prodigious rate, returning all that carbon to the atmosphere over a couple of hundred years. This has resulted in much, much higher concentrations of heat trapping gases and particulates in the atmosphere. Additionally we are making the oceans much more acidic.

We have to stop! We have to decarbonize as quickly as possible. We have started but only by baby steps. The fastest growing carbon free alternative for producing electricity in the US is wind power, which has increases by thirty per cent over the last five years. That’s the good news, the bad news is that that represents less than three percent of our total production.

Our solar electric production has increased by a phenomenal five hundred per cent, but has further to go with only a tiny fraction of one per cent of total electric production. We have a long, long way to go. And there are impediments. One argument against abandoning fossil fuels is that we will be at a competitive disadvantage with other countries that continue to rely on fossil fuels.

So what are our economic competitors doing? What about China? If the objective is to limit carbon release to the atmosphere but China isn’t why should we? And India, if India is still polluting, why do we have to stop? You know in some childish, schoolyard way I guess that makes sense. But we need to be adults about this. We need to provide the global leadership to show the world how it can and should be done.

The US consumes close to one quarter of the world’s resources, yet we constitute a bare five per cent of the global population. It shouldn’t be a matter of what others are doing, but what we need to do to get our house in order.

Actually the “what about China” question is an UH-OH. China is already the world leader in wind power; growing by leaps and bounds, twice as fast as the US over the past five years. How about wind generation as a fraction of total energy production?

wind

wind

Denmark beats us by an order of magnitude, with over twenty per cent of total electric production from wind.

We are similarly behind for solar electric. China is the world leader in the production of Photovoltaic panels, and Germany leads in per capita production, over twenty times the US ratio.German-Solar-Houses

We still have the largest economy in the world and if we were to invest in renewables we could be a world leader in preparing for a carbon-free future. Think American Exceptionalism.

Biofuel is Inefficient

The United States attained the position of a superpower to a very large degree by our ability to utilize fossil fuels. Our way of life requires burning massive amounts of those fossil fuels. The wastes released by burning these fuels is leading to global warming and ocean acidification. If we want to preserve any semblance of a natural environment on this planet we must stop.

To maintain our lifestyle we have to adopt energy production systems that are free from carbon pollution and have long term sustainability. Direct solar, wind, and biofuels derived from crops are three strategies being exploited on a small scale already.

These three energy sources all derive from the sun but are they of equal efficiency? The short answer is NO, in capital letters. Not only are biofuels very inefficient in terms of land use, but also compete with food crops for acreage, fertilizer, and water.

Although the direct tax credits for biofuels like Ethanol and Biodiesel have been discontinued, we continue to subsidize these energy sources by crop price supports and mandates for biofuel use. This is certainly good for agribusiness, but is it good for society?

Consider the productivity of Ethanol from corn. In the United States, we use about half the corn we grow for ethanol production, roughly 50 million acres per year. For this we get 3 billion gallons of gasoline equivalent from ethanol. The problem is that we use over 130 billion gallons of gasoline a year. If we put every arable acre of land in the country in corn (580 million acres), we still would only be able to produce less than half of the fuel we need.

And we would have nothing to eat! The problem with biofuel is that photosynthetic efficiency is very low. That’s why it took hundreds of millions of years to accumulate the fossil fuels were are now consuming.

Of course, there are alternatives to biofuel.

wind turbines

wind turbines

If that same land area is used for wind turbines, solar thermal or photovoltaic applications, much more energy can be harvested. The 60 gallons gasoline equivalent per acre from corn ethanol represents less than 2000 kilowatt-hours per acre per year. Dedicate that same land mass to wind turbines with “good” winds and you get 130,000 kilowatt-hours per acre per year. And the land beneath the wind farm is still available for crops or pasture.

Photovoltaic systems are even more productive.rooftop_PV Virtually anywhere in the US, 800,000 kilowatt-hours per acre per year is attainable with current technology, That is 400 times as efficient as corn ethanol. We don’t need cropland, we can do it on our roofs. We get to eat.

In summary, photosynthesis is a very poor choice when it comes to energy production because it is so inefficient and it competes with food crops for land and water. Solar energy production methods such as photovoltaics and wind with current technology can sustainably power our future, now.