Monthly Archives: September 2014

ozone

Ozone – Stratospheric or Tropospheric

What is the next word you think of if you hear the word ozone? About twenty years ago the answer would invariably have been hole, as in the “ozone hole” over the Antarctic is expanding. Currently if you hear of ozone at all, it is more likely in the form of ozone alerts which occur most commonly on hot summer afternoons in urban environments.

Ozone is another of those Dr. Jekyll, Mr. Hyde molecules. It is at the same time both beneficial and dangerously toxic. It all depends on where it is. Way up in the stratosphere, about 25 kilometers up, it protects us from deadly Ultraviolet rays from the sun, but down near the ground where we breath it is a reactive substance which damages lungs and exacerbates asthma and cardiovascular disease.

There is fairly good evidence for life arising on this planet over 3.5 billion years ago. One hypothesis is that life formed in the seas, as life on the surface of the planet was impossible due to the intense deadly Ultraviolet (UV) rays striking earth. A few billion years later and following the evolution of the chloroplast, oxygen (O2) began to accumulate in the atmosphere. In a cyclic process in the upper atmosphere the more abundant O2 is turned into Ozone (O3). This tiny bit of Ozone absorbs the dangerous UV rays and makes life possible on the surface.

Life then climbed out of the primordial soup and started building air conditioners, refrigerators, and the like which require a refrigerant to work. Compounds know as Chlorofluorocarbons (CFCs) were chosen because they were effective, non toxic and relatively stable. Bear with me here, I’ll get back to Ozone quickly.

Ozone hole over Antarctica

Ozone hole over Antarctica

It’s the stable part got that gets us in trouble. When CFCs escape the refrigerator or air conditioner, they get in the atmosphere. They are stable enough to get all the way up to the Ozone layer without falling apart. There a combination of reactions destroys the Ozone. Enough could literally wipe out life on the planet. Even small amounts of Ozone destruction lead to an increase in retinal damage and skin cancer.

And that is the story of the Ozone hole, a climatically related figure of speech referring to a lessening of the total amount of Ozone in the stratosphere. Luckily we figured this out and by an international agreement known as the Montreal Accords agreed to ban the production and use of these substances. The Ozone hole is slowly shrinking and is by about 2050 expected to be completely healed.

Now back to ground level Ozone, the Ozone we don’t want. Ozone formation at ground level where we breath is not natural. The the fault here is internal combustion engines – Cars and trucks and buses that run of gasoline or diesel.

US-ozone-non-attainment-2007-06

US-ozone-non-attainment-2007-06

Because engines aren’t 100 per cent efficient, some uncombusted gases escape the tail pipe. Known as volatile organic carbon (VOCs), they react with Oxygen and sunlight to produce Ozone. Luckily Ozone is unstable and degrades rapidly so if it forms in the afternoon, it is gone by the evening. Toxic ground level Ozone can be controlled by reducing the production of the VOCs. Reducing the number of cars in urban environments through mass transportation is a very effective measure. Alternately reformulating fuels to produce less VOCs works to some degree, but raises the cost. Natural gas fueled vehicles produce less VOCs and electric vehicles none.

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.  

 

sea ice

More Global Warming Denial

A London, England newspaper, the Daily Mail, recently ran a headline “ Myth of Arctic meltdown: Stunning satellite images show summer ice cap is thicker…than two years ago” This was rapidly picked up and shot around the blogosphere as a renunciation of the risk of Global Warming.

Arctic Sea Ice Minimum Coverage

Arctic Sea Ice Minimum Coverage

Really? REALLY? Based on two data points the paper decides that the work of literally thousands of scientists around the world is all wrong. No, no, no. The trend over the last 30 years of sea ice measurement show that the ice is thinning and the area of coverage is shrinking. Even the casual observer will notice that measurement of climatic variables is confounded by the fact of wide variations in both time and space in virtually all the variables – temperature, rainfall, seal level, etc.

We have warm years and cold years, but overall it is getting warmer when all the planet’s surface and air temperatures are averaged. Even though it has been a relatively cool (and wet) summer here in the central Arkansas, the warmest June in the history of recorded measurements happened in 2014. Given this is just one data point, but how about this: 9 of the 10 hottest Junes ever happened in the 21st century.

Another misleading claim is that global warming has stopped or at least slowed over the last few years. It is true that over the last few years it has not been getting hot as fast as previous years. The rate of heating has slowed somewhat, but only when you average surface and air temperatures as mentioned above.

The causative agent for global warming, the amount of heat trapping gasses in the atmosphere, are inexorably increasing, hence the a factor called radiative forcing is increasing. The real question is where is the missing heat. An article published recently in Science, the premier peer reviewed science journal published in the United States, has the answer.

It’s hiding in intermediate depths of the Atlantic and Southern Oceans. New data coupled with reanalysis of previously collected data show that a recurrent anomaly in salinity is the culprit. Changes in the saltiness of water affect its density, which can cause upwelling of the colder deeper water. When the colder water is brought to the surface it warms, absorbing heat.

Major ocean currents such as the Gulf Stream are driven by these kinds of differences in temperature and salinity. The Gulf Stream transports heat from Florida to Europe. Disrupt it and it could get hotter in Florida and colder in Europe.

Gulf Stream

Gulf Stream

In a related story, seeps of methane have been detected in the Atlantic ocean. Much methane lies near the continental shelf trapped in ice crystals known as clathrates. Warming of the water in the area of the clathrates could cause thawing which would release the methane.

The story gets even scarier when you consider that methane is a powerful heat trapping gas itself. Global warming is causing the release of methane which causes more global warming which causes more methane release – and around and around we go.

Ivanpah tower

Solar Thermal Electricity Generation

After spending a near cloudless weekend on the Buffalo National River, my thoughts turned the considerable power of heat from the sun. When concentrated the sun’s heat can be used to do work, specifically generate electricity.

A new facility has begun operation near the Nevada border in the California desert. Ivanpah, CA in the Mojave desert is home to a solar thermal power plant covering a little over five square miles. The plant produces enough energy to power 140,000 homes (377 megaWatts.)

The plant consists of three towers each surrounded by thousands of mirrors.

Ivanpah plant

Ivanpah plant

Computers control where the mirrors are pointed such that they are always pointed at the top of the tower. There boiler tubes convert water to steam to at very high temperature and pressure. This is used to turn turbines for the generation of electricity. It works just like a conventional coal or nuclear power plant, but without the carbon emissions or radioactive waste. Clean sustainable energy.

Solar thermal power technology is not really all that new. A solar thermal power system was demonstrated at the the 1878 World’s Fair in Paris. A 20 square meter parabolic reflector, basically a light concentrating mirror, was used to make steam to run a printing press. Other solar thermal plants employing power towers have been built but the Ivanpah plant is by far the world’s largest and most efficient.

It is very efficient in multiple ways. Solar photovoltaic plants, usually seen on rooftops, are also configured in large numbers in fields to produce power for the grid and operate at about 15 per cent efficiency. The Ivanpah facility captures upwards of 20 per cent or more of the sun’s energy.

A unique feature of this solar thermal plant compared to other sustainable but intermittent power sources such as wind and solar PV is the ability to generate power around the clock. Some of the day time heat energy from the plant can be stored in special insulated reservoirs containing molten salt solutions. At night, generators can be run off of steam produced by water circulated through the heat storage reservoirs.

Another important variable in any thermal power plant is water use. This is especially important in the desert. When water is heated to make steam, it can only be used to do work if and when it is cooled back to water. Cooling the steam can use lots and lots of water. That’s why you see thermal plants like coal or nuclear fired plants located near large bodies of water – rivers, lakes, even sea coasts. The Ivanpah plant uses an air cooled system to condense the steam so it is particularly frugal when it comes to water use.

To complete the discussion I should mention downsides, two come to mind. First is land use, solar thermal plants of this type require relatively large areas in sunny climates. Luckily we have much desert land that with proper oversight to protect natural habitat can provide a significant amount of electricity production.

Finally there is the issue of bird kills. Some species of birds, especially fly catchers are being killed by flying into the heated air near the towers. Estimates are that about 30,000 birds are killed per year. That may sound like a lot but compare that with the number of birds killed annually by collisions with man made objects. A billion, yes that is a billion with a capital B, birds die from running into windows, and towers and what not.