Tag Archives: clean energy

near a wind farm in western Oklahoma

Anatomy of a Scam

In 2008 reports of a new style of wind turbine for producing electricity began showing up on “techie” web sites. The turbine was touted as a small powerful shrouded turbine which would produce energy in low winds and because of the shrouded design much less likely to be dangerous to birds and bats. On a website in 2008 Phillip Ridings claimed that his turbine design, patent-pending, was so efficient that it produced more energy than simple physical principles would allow. His turbine is called the dragonfly-turbine.

When asked about the violation of the physical law known as Betz limit, Mr Ridings replied “I did read “Betz Law” and it does not affect it because of Dragonfly’s unique design. If you want to apply Betz Law then its about to be broken.. just like the sound barrier!“

In 2010 Mr Ridings was interviewed on another website and claimed that his as yet unbuilt turbine would produce 2.4 to 4 times as much energy as a conventional turbine (or was 60% more efficient depending on which part of the interview one was reading.)

Although as of this writing there is still no real turbine, Mr Ridings claimed to have orders for turbines and was establishing a network of dealerships. None have been built, much less tested, other than via computer modeling.

Dragonfly Industries International was founded in Texas with Phillip Ridings as the managing member of the limited liability corporation in September 2014. The company is seeking or has purchased a 311 acre parcel of land in Northwest Arkansas to develop a wind farm. They claim to have a 1 megawatt (MW) shrouded turbine design ready to be built. The plan is to deploy 80 of these turbines on only a small portion, 80 acres, of the site, hence an 80 megawatt wind farm.

This is physically impossible. On a land use basis alone the farm is highly unlikely. Wind farms require a lot of space because turbines create wind shadows and turbulence. The National Renewable Energy Laboratory, a division of the Energy Department, reviewed the data for wind sites around the country, mainly in the midwest where winds are strong and found that the average area needed per megawatt of energy captured was 85 acres. That’s 85 acres per MW. Dragonfly claims to need only 1/85th as much land to produce the same amount of power, 1 acre per MW.

The proposed 20 foot diameter turbine is claimed to be able to produce 1 MW of power from a 17 mph wind. It is unlikely that there is a consistent 17 mph wind in Northwest Arkansas, but regardless, a turbine of this size cannot produce that much power. The maximum amount of power in wind can be calculated if you know the swept area of the turbine and the wind speed. For the claimed turbine the maximum power available is slightly less than 8 kW. But due to Betz limit it is about 5 kW and for a turbine of this size considering mechanical inefficiencies about 3 kW is realistic estimate. Not 1000 kW.

A simple analogy is instructive. Take an orange and squeeze the juice out. You could get about 2 to 3 ounces. If however you were as good at squeezing as this turbine is at producing power, you could get 2 to 3 gallons! If it sounds too good to be true…

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.

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.

Geothermal Energy

The term geothermal has come to be associated with two technologies which are only tangentially related; first, power can be produced by drilling into the ground to a depth where the rock is hot enough to boil water. The other use of the term geothermal is associated with ground source heat pumps which need only drill down a few feet to a temperature of fifty to sixty degrees Fahrenheit.
 
Utility scale power can be produced by drilling into the ground to a depth where the rock is hot enough to boil water to produce steam. The steam is then used to drive a turbine to generate electricity just as a nuclear reactor or a coal fired power plant produces steam to turn turbines. Electricity production from geothermal heat requires drilling several kilometers into the earth and is consequently very expensive, but in certain locations heat is near enough to the surface to make its utilization practical.
 
Heat at the core of the earth is approximately 6000 degrees Celsius, hence a temperature gradient exists: twenty five degrees C per kilometer. The heat is due to at least two factors, residual heat from the accretion of the planet over four billion years ago and radioactive decay of certain elements such as Uranium and Thorium.
 
To economically produce power, hot rock must be within three or four kilometers of the surface. This only occurs in geologically active regions, such as areas with earthquakes and/or volcanoes. In these locations fissures in the earth’s crust allow movement of magma near enough to the surface to be exploited for power production.
 
The simplest design for a geothermal power plant takes advantage of hydrothermal convection. Cool water from the surface seeps underground, is heated and then rises back to the surface. The heated water, now steam, is obtained by drilling wells to capture the steam and directing it to turbines for energy production. The water from the condensed steam can then returned to continue the cycle.
 
Although the heat is essentially free, the cost of drilling and maintenance of equipment can be high. Subterranean steam extracts caustic materials which corrode even the most inert metals. A limiting factor for energy production can be the rate of heat transfer through rock. As heat is extracted from rock surrounding the well site, heat must be transferred through the rock, limiting the rate of heat extraction.
 
The United States leads the world in geothermal electric capacity. The US has about 2.7 GigaWatts installed, a quarter of world capacity. Twenty six plants in one location called the geysers,

geysers north of San Francisco, accounts for three quarters of the total US production. For comparison, one nuclear reactor has a capacity of just under one GW.
 
Parts of Alaska, Washington, Oregon, California, and much of Nevada and Hawaii have potential for geothermal electricity production and much of the Rocky Mountain area could extract useful heat for direct uses such as space heat for apartment buildings, schools, and other large facilities.