Common Science Fifth Anniversary Column

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This week marks the fifth anniversary of Common Science® and this is my 239th column! It’s been my great pleasure to write them and I have enjoyed your comments and emails over the years. Nevertheless, I’ve decided that I need to take a little hiatus from writing.   In the mean time, I will still be on the air with Aaron Keck on 97.9 FM/1360 AM WCHL and streaming live on Monday afternoons at 4:32 pm for our usual geektastic science discussions.    For this fifth anniversary column, I have decided to review some of the key themes and points I have tried to share with you over the past 5 years.

  1. Almost all of our energy comes from the sun.

The energy contained in coal, petroleum, and natural gas and biofuels is all derived from photosynthetic plants capturing solar energy. Solar electricity comes directly from the sun and wind energy is the indirect result of uneven heating of the atmosphere by the sun. Even hydroelectric power is dependent on the evaporation of water by the sun as part of the water cycle.

The most important part of the energy-from-the-sun story to keep in mind is that fossil fuels – coal, oil, and natural gas – represent solar energy captured by plants hundreds of millions of years ago. Exploiting these fossil fuels allows us to use many, many years of solar energy in a single year. As fossil fuels are used up, we’ll need to learn to live on just real-time solar energy.

  1. Everything comes from oil

One of my very first columns was titled, Everything Comes from Oil, Everything, because it does. All plastics come from oil. So do things carpets, clothing, paint, fertilizers, pesticides, glue, tape, soaps, and bowling balls. Even aspirin comes from oil. When oil becomes scarcer as the century proceeds, everything will become more expensive.

  1. Transitioning to renewable energy will be very difficult.

Most stories about the increase in the amount of renewable “energy” being produced contain several misleading points in common. They almost always describe growth rates in the amount of renewable energy produced by using a percentage rather than an absolute amount. Thus, when you read that the amount of renewal energy produced in the United States has increased by 30% it sounds quite impressive. If they instead noted that the share of renewable energy produced in the United States had increased from 1.0 to 1.3%, you might not be so enthusiastic. However, the second statistic gives you a much clearer picture of what is really going on and tells you the story of the long, long way we have to go.

Another common problem is the misuse of the word energy. It is not uncommon to come upon a story that says something like, “Last Week Germany ran on 80% renewable energy”! These stories are all incorrect. What they mean is that Germany produced 80 of its electricity by renewable means. This leaves out all of the energy used to power cars, trucks, and boats as well as fuel burned to power industrial production and to heat buildings. If you do the math, this story should quote 10% rather than 80%. That’s a big difference.

  1. Biofuels are not helping us.

There are three types of biofuels. Ethanol is made by fermenting plants with sugar or starch like corn or sugar can. Vegetable oil can be made from soy, palm, or other oily plants. Vegetable oil can be burned as a fuel directly or converted to biodiesel by reacting it with methanol. (If this summary were longer, I would take the time to point out that methanol is product of natural gas, which makes biodiesel not so bio after all.)

The growth in the use of biofuels is driving the destruction of rain forests across the globe. It is also crowding out subsistence farmers around the world as their governments lease their arable land to other countries to grow and export vegetable oil. Considered in this light biofuels are not so sustainable. If you want to really depress yourself some time, look up how much arable land in Liberia has been leased to other countries.

Please note that the process of collecting used cooking oils and greases and converting them to fuels as practiced by Piedmont Biofuels in Pittsboro, NC is a sustainable model.

  1. To understand the impending crisis on fresh water you need to consider aquifers.

Growing food and maintaining adequate hygiene for seven billion humans requires tremendous amounts of fresh water. In particular, irrigated fields produce far more food than those that depend on rainfall alone. In order to provide sufficient amounts of irrigation water, farmers dig wells in to underground aquifers. These aquifers can be incredible large and are filled with water that fell years, decades, or even millennia before. By utilizing this “fossil water”, humanity now uses more fresh water each year than could be supplied by rainfall alone.

The problem, which is now beginning to rear its ominous head, is that these aquifers are beginning to run dry. I often try to explain the dynamics of aquifers and wells by using the analogy of a glass of water and a straw. As long as the glass has any water in at all, you can keep drinking from the straw at essentially the same rate as when the glass was full. Then, when you get the bottom, the water flow drops to zero in a sudden manner. This is analogy is currently playing out for farmers in places ranging from northern India to west Texas.

Over the next 50 years or so, we are going to have to learn to live with the limited allotment of rainfall that Mother Nature provides. This will be an exceedingly difficult transition and is likely to be the cause of local, regional, and global conflict.

  1. The study of the microbiome will be a key feature of 21st century medicine

Human beings co-evolved with our populations of resident bacteria, our microbiome. The number of bacterial cells in your body far outnumbers the human cells. Furthermore, since bacterial cells are genetically more complex than human cells, over 90% of all of the genes within your body are bacterial. If you spend enough time studying this dynamic as I have, it can profoundly impact the way you view the human body. First you consider bacteria to be ancillary and then as vital partners. Then the idea that bacteria are actually in charge and have been driving the design and function of the human body to fit their needs starts to creep in.   I plan to address this idea in future radio show about why humans kiss and hold hands. But, I digress.

Over the last 10 years, we have just begun to uncover what the bacterial genes iun the microbiome are doing and how integral they are to our health and well-being. For example, we now know that our microbiome is a key factor in issues ranging from maintaining a healthy body weight to cardiovascular and mental health. We ar on the cusp of learning a lot more.

  1. The Keystone XL Pipeline debate was a distraction

The debate over whether or not to build the Keystone XL pipeline spanned at least two presidential campaigns. Had it been built, it would have made the transport of heavy crude oil from the oils sands in Alberta to refineries on the Gulf Coast of the United States somewhat easier. During the entire period of debate, the oil sands were being actively exploited and the heavy crude travelled to the refineries through the multiple other existing routes. The key issue in this debate should have been that in order to maintain a reasonable climate, we need to leave the oil sands in the ground. Focusing on the transport of the oil rather than the extraction of the oil missed the key point.

There is a bit of irony on this front to explore as well. About 20% of the oil in the sands of Alberta is “easy” to extract. The process is akin to strip mining. The other 80% is much harder and expensive to exploit. The planned method is to inject steam into the deposits to melt the oil and then pump it out using standard oil well equipment. Initial trials of this method are not going well as the melted oil seems to have it’s own mind about which direction it wants to flow.

Just as the “easy” 20% of the oil sands is running out, implementation of fracking in the United States has increased global oil supply by 2-3% and, along with other factors, this is lowered the price of oil around the globe.   Therefore, had the Keystone XL pipeline been built and ready to transport oil from Alberta to Houston, it’s not at all clear that it would have been heavily utilized.

  1. GMO’s are a distraction too

Almost all corn and soybeans in the U.S. are made from genetically modified seeds, or GMO’s. In today’s highly processed food system, GMO corn and soybeans are in nearly everything. Yet these “Frankenfoods” are not causing harm to people, at least not directly. From the point of view of the human digestion system, the molecules within GMO versus non-GMO foods are essentially identical.

What is doing harm, and where our focus should be, is in the problems related to the monumentally large, monoculture fields that GMO food production engenders. Tilling up most of the Great Plains each year releases the carbon held within the soil to the atmosphere. Monoculture fields only blossom once a season, making them a food desert for bees and other vital pollinators the rest of the time. In addition, since the GMO crops can withstand pesticides, all other weeds and plants in the area can be and usually are wiped out. This removes food sources for pollinators as well. Since 70% of all of the calories we eat come from pollinated plants, we need to look after the pollinators.

Lastly, the problem with GMO corn as a food source is not that it is GMO but rather that we grow far too much of it. The ocean of cheap corn produced in the United States results in high-fructose corn syrup being introduced into many foods along with its empty calories. Corn has also become the primary food source for cattle, chickens, and hogs. The meat and eggs produced from livestock that are fed this way are far less nutritious compared to those from pastured animals.

  1. Think Local act Local

Many factors that impact our lives are beyond our local sphere of control. We can’t influence how much coal is used in India or China and we can’t seem to prevent the North Carolina General Assembly from passing odious legislation. But there are key aspects of our local environment that we can and should zealously protect.

First, consider our position with regard to water. (Full disclosure. I am a member of the OWASA Board of Directors. The statements below are my own.) Watersheds and aquifers in Orange County, NC are highly localized in that we do not draw our water from rivers or lakes that are shared with other locations. This means that we have a high level of control on water use, water quality, and management of aquifers through prudent regulation of wells and withdrawals. So far we are doing an excellent job of managing our water resources and should focus on continuing these efforts.

We need to keep an eye on our soil and our land use. Topsoil is a vastly underappreciated resource. Healthy and sufficient topsoil is the key element in producing local food. Protecting topsoil requires a sustained multi-pronged effort. Land use and zoning regulations need to guard against having our topsoil scraped off and trucked away and we need to require adequate stream buffers in our zoning laws such that our topsoil does not erode and float away. We also need to support programs that subsidize sustainable farming methods such as no-till farming and integrated used of livestock.

Lastly, we can and should take care of our local pollinators. North Carolina has over 300 species of native bees. I own and operate a small local farm. So I can tell you from first-hand experience that allocating a small portion of the land to meadow and natural wildflower beds can dramatically increase the number and diversity of local pollinators on site, which results in increased yield. We can all support our local farmers and local pollinators by planning flowers and allowing for natural areas wherever possible. Every little bit helps.

Thanks again for your support and participation these last five years. Come listen to Aaron and I on the radio and I’ll be back in print in a couple of months.


Jeff Danner celebrated 5 years of Common Science on WCHL with Aaron Keck (and most of the WCHL staff).


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Why Solar Roads are a Bad Idea

If you paid attention to the news last spring, you may remember that solar roads were experiencing their 15 minutes of fame. There were newspaper articles, TV reports, viral Facebook messages, and at least one Kickstarter campaign to fund this ambitious project. The concept was to start covering our roads with small, modular solar panels to generate electricity. The implication of most of the reports was that generating electricity from our roads was going to usher in a golden era of plenty, and generally included an undertone suggesting that we had somehow been blind in not perceiving this veritable cornucopia of energy before. Then suddenly the 15 minutes were over. Let me explain why.

solarroadsThe electricity-generating part of a solar panel is made from a semi-conductor, usually silicon. A semi-conductor is just what it sounds like: something that will conduct electricity, but only a little bit. When sunlight shines on a solar panel, electrons migrate away from one of the surfaces and towards the other. If I now connect these two surfaces of the panel to a circuit, electrons will flow through the circuit. Voila, electricity! The type of electricity generated by a solar panel is direct current (DC), which means that electrons flow through the circuit in the same direction all of the time.

In contrast to the DC electricity generated by a solar panel, the electricity in our homes is alternating current (AC). In an AC circuit, the electrons move back and forth, switching directions 60 times every second. In order to understand why our houses have AC rather than DC electricity, we have to go way back to the 1880s and the War of the Currents.

By the 1880s, Thomas Edison had accumulated a number of patents for the generation and distribution of DC electricity and was collaborating with George Westinghouse to commercialize them. At about the same time in Europe, a number of inventors and engineers were developing AC technologies. In order to get a better understanding of these developments in Europe, in 1884 Edison hired Nikola Tesla, an electrical engineer who had been born in the Austro-Hungarian Empire in 1856. Not long after arriving in the United States, Tesla learned that due to Edison’s ego and personal attachment to DC electricity, he would not have a real chance to continue his work on AC technologies. So Tesla found some investors and struck out on his own.

Tesla soon had several patents for AC technologies, several of which he licensed to Edison’s former partner, George Westinghouse, and the War of the Currents was on. It was a nasty public battle filled with misinformation and personal invective. In an effort to “prove” that AC current was far too dangerous to unleash on the American public, Edison inadvertently invented the electric chair. In what may be considered a bit of macabre foreshadowing for our current difficulties and controversies over executions and the death penalty, the first use of the electric chair for an execution in 1890 went very poorly and several cycles were needed. George Westinghouse quipped “It would have been better done with an axe.”

Despite his valiant efforts, Edison was doomed to lose this battle before it started. Physics was against him. For reasons of which I will spare you the explanation, when you transmit direct current over any reasonable distance, much of the electricity is lost. Let me give you an example from personal experience. I have written previously about the solar power system that I built at my farm, which uses a single 220 Watt solar panel and four batteries. Approximately two feet away from the panel, I have a refrigerator which I use to store chicken eggs, vegetables and cold beer. It runs like a charm. About 150 feet from the solar power station is my tool shed. I ran a heavy gauge wire over to the shed – the thicker the wire the less the electricity loss – and I can just barely run a radio, a device that needs far less power than a refrigerator.

The beauty of AC current is that it can be transmitted over long distances with limited loss. This technical advantage explains why Tesla won the War of the Currents despite Edison’s head start and considerable fame. It is also the primary reason that electricity generation and distribution in the United States came to rely upon a relatively small number of very large power plants which deliver electricity over great distances.

The issues which impacted the War of the Currents are the same ones which determine the viability of solar roads. We could certainly cover the highways of sunny places in the U.S. such as New Mexico and Arizona in solar panels and generate quite a bit of DC electricity. However, given that highways are generally far away from homes and businesses, trying to transmit power from the roads to where it is needed would waste nearly all of it. One could consider using streets in cities and towns, but as you can see from my example from my farm, even the short distance from the street to your house would result in a noteworthy loss of power.

A far better place to install solar panels is where we generally already do install them: on roofs, which is as close as possible to lights, TVs, and appliances. Furthermore, rooftop solar panels are getting so efficient now that they are beginning to compete with your local electric company on a cost per kilowatt hour basis.

Sadly, I think the brief flurry of interest in solar roads actually hurt the alternative energy movement. Getting everyone’s hopes up on an unrealistic project and then letting them down creates negative feelings. In the end, as is often the case, the best approach is not always the sexy one. Rooftop solar panels are a key feature in helping us to become less dependent on fossil fuels, and we should just keep making steady progress in installing them.

Have a comment or question? Use the interface below or send me an email to Think that this column includes important points that others should consider? Send out a link on Facebook or Twitter. Want more Common Science? Follow me on Twitter at @Commonscience.

How Engineers Spend their Spare Time

Since I started writing Common Science in April of 2011, I have averaged 50 columns a year.  Most weeks I have my topic selected by Monday, a first draft done by Wednesday and am ready to submit to my editor (she’s not hard to find) by Friday.  This routine keeps me on track to publish on Sunday afternoons.  Once or twice a year something goes awry during the week, Friday morning rolls around and it’s clear the column is not going to come together. Well, it’s Friday morning now and this is one of those weeks.  Maybe I can take a shot at fixing this week’s first effort in the future, but in the meantime, let me tell you about a project I am working on.  It should give you a little insight into how engineers spend their spare time, a question that I am sure has been plaguing you.

As I have mentioned in previous columns, I have a “farmette” west of Carrboro where I grow vegetables, generate my own electricity, raise chickens and bees, and am attempting to create a local pollinator refuge.  Designing and building projects and systems for the farm is a relaxing and enjoyable hobby for me.  Lately I have been working on improved systems for growing tomatoes.  I love tomatoes and want to grow my own all year long.  However, like most gardeners I know, I find the task of staking and trellising them to be tedious and the solutions offered for this by the local garden shop to be inadequate.
tomatoesThe staking problem can be resolved by growing tomatoes upside down.  You can buy expensive planters for this approach if you like.  I use inexpensive two gallon buckets hung from a pole with a hole drilled in the bottom.  Here is a picture of some tomatoes hanging upside down in my greenhouse (more about the greenhouse below).   At this early stage, the plants grow out to the sides of the buckets and then upwards towards the sun.  Once the tomato fruits get large enough, the plants are weighed down and the vines hang below the buckets.  It’s a wonderful way to grow tomatoes, no staking and no weeding.
greenhouseThe primary flaw in the upside down tomato approach is that the buckets, being suspended in the air, subject the plant roots to much larger temperatures swings that they would experience if planted in the ground.   This can quickly kill the plants either by freezing or frying the roots.   In order to try to provide an environment with better temperature control, I built the green house pictured here.  To keep costs down, it’s built from some 2” by 3”s, a couple of shed wall panels, and the roof and top third of the walls are made from corrugated clear plastic panels.  The cost for all of the materials was a little less than $250.

I started my first batch of tomatoes in the greenhouse last April.   For a couple of months they looked beautiful and I was feeling like a gardening genius.   Then we had a hot spell in June. The temperature in the greenhouse shot up to over 100 °F and the plants began to wither.  I bought a thermostat and two exhaust fans which would run on the 12 VDC power coming from my solar electric station (1) to blow the hot air from the top of the greenhouse out while sucking in somewhat cooler air from vents near the ground.  This helped a little bit, but by mid July I had lost all of the plants. Next summer I intend to purchase a reflective mesh to put over the roof to see if I can keep temperature below 90 °F while still letting in sufficient sunlight.

Meanwhile, I started a new batch in the green house in August and now have some promising-looking ¾” diameter, green tomatoes. (These are the ones pictured above.) My current concern is that before they have a chance to ripen, we will have a cold snap and the plants will freeze.  To prepare for that possibility I started on a new project this week, a solar water-heating system for the greenhouse.

solar collectorMy first step was building the solar collector pictured here.  The box is built from treated lumber.  On the bottom is a 1” thick sheet of foam board insulation covered with aluminum which I painted black to absorb sunlight. (2) Next I constructed and installed the copper serpentine you see in the picture.  Soon after this picture was taken I painted the copper piping black as well.

The next steps are to cover the collector with a sheet of glass – I am using an old window I bought at the Habitat for Humanity Restore (love that place) – face the collector to the south, tilt it to approximately 30° from verticle, and fill the serpentine with a water/antifreeze solution.  When the sun warms the liquid in the tubes it will start to rise due to reduced density.  The liquid coming out of the collector will flow through an insulated hose to a small tank located high within the greenhouse.  From the tank the water will fall by gravity through another serpentine which will be embedded within a concrete block located inside greenhouse.  As the liquid flows through the block it will warm the concrete.  After passing through the concrete the liquid goes back to the bottom of the solar collector to be warmed again and the cycle continues.  This sort of temperature-driven liquid flow is called a thermosyphon.  Here is a simple schematic of the system.

If my calculations are correct, the heat stored in the concrete block should be sufficient to keep the air inside the greenhouse above freezing on even a cold Chapelboro night, and we’ll be having fresh homegrown tomatoes for my birthday in January.  I’ll let you know how it works out.

Have a comment or question?  Use the comment interface below or send me an email at

(1) Consistent readers will have noticed that I have been using more footnotes of late.  As I write these columns a large number of tangential topics come to mind.  I used to weave these into the narrative of the column which created for a fair bit of clutter.  So I am trying to put more of those thoughts down here.  In this case, I wanted to remark on the absolute joy of running equipment from electricity you make yourself.  This is not difficult to do, and if you like tinkering around with things, I highly recommended it.  Unfortunately, there is not a supplier of solar electric equipment in the area, nor is it easy to find equipment, thermostats, pumps, etc. which run on DC power.

(2) If you are installing a solar water collector to heat water for your house, you want to use expensive solar absorbing paint rather than just black spray paint.

Orange County Welcomes Solar Power

White Cross Farm

CHAPEL HILL – The sun’s rays now cannot only brighten your days, but also your home.

In early July, Strata Solar teamed with Orange County to begin construction on a 35-acre, six-megawatt solar farm on White Cross Farm in Chapel Hill.

After about twelve weeks of construction to install more than 26,000 solar panels, the sun’s light will provide power to about 750 homes in the area, says Vice President of Sales and Marketing at Strata, Blair Schoff. Schoff says, though more difficult, the builders even continued to make progress during the heavy rains of early July.

He says the construction can take up to 120 workers to get the land ready, drive posts, mount solar panels, and wire the electrical work.

Schoff says the farm generates power, which is sold to utility companies, and businesses and residents close to White Cross Farm will consume most of the solar power.

“One of the things that we’re trying to do is add additional green power to the grid,” says Schoff. “It helps the utilities because a lot of their peak demand is during the day when businesses and air conditioners are being used at their peak and we’re providing them the alternative of having energy generated by the sun added to this mix.”

Schoff says Duke Energy will receive the solar power from White Cross Farm, and then provide it to local residential and commercial clients.

He says using solar power benefits the environment and eliminates 4,224 tons of carbon dioxide from being emitted annually by other power sources, like coal.

“There’s no moving parts,” says Schoff. “There’s no noxious fumes. There’s no liquids being dropped into the soil. It’s very clean, renewable. It’s an excellent source of renewable generation.”

Solar power relies on electrons for power.

“Solar panels, the type that we use, it’s essentially silica that’s cut into wafers,” says Schoff. “One of them has a treatment on it with an element that is interested in yielding electrons. Another wafer has a treatment on it with an element that is interested in gaining electrons. Those two wafers are essentially sandwiched together. The photon, from the sun, of enough energy catalyzes the reaction where that electron from one wafer is liberated and is finding its way toward the electron on other and we try to harness as many of those electrons as we can and use them as power.”

Many farms have the necessities for a solar farm, but Schoff says White Cross met the standards.

“There’s a certain criteria that we look for in any of our farms,” says Schoff. “Having a farm that’s flat with access to the appropriate infrastructure are the key components. White Cross and that property just happened to pick all the boxes to make an appropriate solar farm.”

Headquartered in Chapel Hill, Schoff says Strata Solar is excited to build so close to home.

Strata Solar is in the midst providing solar power to many other places across the state. It is developing eight farms in the Triangle and two in Orange County.

Schoff says everywhere could benefit from solar power.

“All counties have a need for solar power,” said Schoff. “It’s not just Orange County. It’s the state of North Carolina. It’s the country.”

For more information on Strata Solar, click here.