Monthly Archives: November 2019

Pumpkin Eater

Other than the turkey itself, no other foodstuff says Thanksgiving like pumpkin. Notably, both the turkey and the pumpkin are native to the Americas. Turkeys and pumpkins both were supposedly components of that first meal shared by native Americans with the colonists. Pumpkin pie is so ubiquitous that the combination of spices used to flavor it – cinnamon, nutmeg, cloves, and ginger – have come to be called pumpkin spice, and that flavor shows up in a number of the products we consume this time of year.

Pumpkins are in a large family, Cucurbita, with over 900 species. These species include gourds, winter and summer squash, all sorts of melons, and even cucumbers. Native Americans over thousands of years transformed what we know today as a Pumpkin from a tennis ball sized gourd with a very bitter taste.

As are so many other things we eat, pumpkins were made palatable via selective breeding. Pumpkins originated in Central America, and seeds of domestic Pumpkins dated to 8,000 years Before the Current Era (BCE) have been found in the highlands of Mexico. Softer, sweeter pumpkins were chosen from the wild or selected from purposeful plantings. This process continues to this day. Burpee’s Catalog offers 26 varieties of pumpkins.

The story of the post-human-manipulation pumpkin is interesting in and of itself but the natural history of the pre-humanpumpkin is also exciting. There is evidence that megafauna: mastodons, mammoths, giant sloths, etc., were an important part of the pumpkin’s story. Deposits of mastodon dung dated to 30,000 years ago contained squash seeds. The survival of the seeds after passage through the digestive tract of the megafauna provided a means of dispersal and fertilization which is valuable mechanism for evolutionary success.

It is quite likely that the bitter taste is important to this story. The bitterness of the ancestral pumpkin was due to compound called Curcubitacin which not only imparted the bitter taste but was also toxic. Plants and animals have been duking it out over billions of years. Plants have evolved to produce a great number of toxins to prevent herbivores from damaging their reproductive parts or seeds.

Had small mammals eaten these squash, they surely would have also eaten the nutritious seeds. And here is where the bitterness comes in. Modern gene sequencing has shown that among mammals at least, there is a correlation between sensitivity to the bitter taste and size. Sampling animals from rodents to elephants has shown that the smaller the animal, the greater the sensitivity to bitterness. Small mammals such as rodents avoided the bitter plants leaving them to the megafauna.

The effect is that early pumpkins allied with the megafauna to promote a type of mutualism. The megafauna got the benefit of the pumpkin as food while the pumpkin benefited by dispersion/fertilization. The demise of the megafauna would have been a problem for pumpkins, but luckily humans came along and partnered up. Pumpkins are now cultivated around the world, a range far in excess of its ancestral home.


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

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.

Leaving Paris

President Trump campaigned on the denial of climate change, calling it a Chinese hoax. Upon election, he announced that the United States would be withdrawing from an agreement reached among every nation on earth. Despite the world’s scientists, the world’s scientific organizations, and the world’s governments agreeing that climate change is an existential threat to humanity and our environment, the government of the United States says no.

Despite polling showing the majority of us agree that climate change is occurring and action needs to be taken and despite the fact that the size of this majority is growing over time, the Trump administration continues to roll back regulations meant to combat global warming.

The full name of the agreement is “the Paris Agreement under the United Nations Framework Convention on Climate Change. “ It is also referred to as COP21, the 21st Conference of Parties. This agreement was designed to improve upon and replace the rather ineffectual Kyoto Protocol from 2005.

The agreement is an international treaty that has been ratified by UN members representing nations that produce in aggregate over 55 percent of greenhouse gas emissions. This means very few nations representing major emitters could effect ratification of the treaty: China, USA, India, Russia, and Japan would be all that is necessary. In fact, 197 countries have ratified the treaty.

The treaty created individualized targets called Nationally Determined Contributions (NDCs) for greenhouse gas reductions. The developed nations have targets with steeper reduction curves compared to the developing world. The argument is the countries of the developed world are principally responsible for the excess of greenhouse gasses and therefore should bear the lion’s share of the reductions.

President Trump formally notified the international community this week that we will withdraw from the agreement next fall. The date for the formal withdrawal is one day after the 2020 elections. Even if he loses his bid for re-election he is still president until the inauguration of a new president.

Since at least the end of World War II, the United States has been the world leader in science and technology and a moral guidepost for the world. By disengaging from this treaty we are telling the rest of the world that we don’t care. By abandoning the objective of lessening of the risk of climate change also means that we will be less focused on science and technology to achieve the end.

The solution for addressing climate change is a moral one – we need to recognize reality, and a scientific and technological one – developing new ways of producing the energy we need to power our society with less greenhouse gas emissions.

China is the world leader in installing wind and solar power sources in total. On a per-capita basis, Denmark is the leader in wind and Germany for solar.

We literally stand along among the nations of the world in our direction of change. As the world moves to cleaner renewable energy our government is moving to subsidize fossil fuel utilization.

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

Carbon Control

Energy production from burning fossil fuels is a classic example of the failure of capitalism to protect us from harm. The fossil fuel industry privatizes profits while socializing costs. Fossil fuel combustion products damage our health and the environment and endanger our future due to global warming.

Some laws have been enacted to protect us. Coal-fired power plants have to have filters to remove some particulate matter and substances which contribute to ill health yet as many as fifty thousand deaths a year are attributed to fossil fuel emissions. These are deaths not accounted for by capitalism.

The biggest threat to global stability and human health is now climate change. There are currently no limits on fossil fuel emissions to protect us. One way to make the user pay the costs would be to put limits on the Carbon Dioxide (CO2) emitted. The process to remove CO2 is called Carbon Capture and Storage (CCS.)

If CCS can be made to work, we could have our cake and eat it too. That is, we could have the benefits of energy from burning fossil fuels without negative consequences. Basically, CCS is a process of capturing the Carbon Dioxide waste stream from a power plant and then putting it somewhere other than the atmosphere.

The problem is that it is neither cheap nor easy. CCS technology could double the construction and operating costs of a power plant. The major limitation is the need for storage sites such as airtight underground caverns or the ocean depths, where the carbon dioxide would stay for a long, long time. Like forever.

The best site would be a geologic formation where subsurface rock naturally reacts with carbon dioxide via a process that chemically mineralizes it. These formations exist but are few and far between. We need enough storage space for about five billion tonnes of carbon dioxide a year.

Without mineralization, storage becomes much more difficult. Carbon dioxide, a gas at normal pressure, would need to be pumped into storage wells and the wells then capped to prevent release. At atmospheric pressure, it would require over six thousand cubic miles of underground open space per year. This kind of space doesn’t really exist, hence pressurization is necessary to reduce the volume. The higher the pressure the more difficult it will be to contain the stored gas. Any leakage will increase the cost both economically and energetically- all that capture, transportation, and pressurization uses energy.

The only way to store the five billion tonnes of carbon dioxide produced every year seems to be by pumping it at high pressure into every hole in the ground that we can find, plugging the hole, and then hoping that the cap doesn’t come off – forever. But what if a storage site does burp? It could be lethal for just about every living thing in the area of the release of CO2.

Carbon capture and storage in the last analysis is expensive, uses a lot of energy, and is quite risky to all life in the area of the storage wells. The only real solution is to abandon the use of fossil fuels and get all our energy from clean, sustainable energy supplies.

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

Arkansas Lithium

There is no question that electric vehicles are the future. Although projections are all over the map, a decent guess is that by 2030 something like fifty percent of new car sales will be electric. The number for fleet vehicles such as cabs, urban buses, and delivery vans will be even higher. They will all need rechargeable batteries and right now Lithium is the material of choice for those batteries.

Most metals can be used in batteries and the periodic chart is populated by scores of metals. In fact, the majority of elements in the universe are metals. What makes Lithium unique is its charge to weight ratio. Lithium is the lightest metal and can exist as a stable ion. This means it is capable of giving up or accepting an electron, a necessary function of a battery.

Think of a charged battery as a reservoir of electrons. When a battery-powered device is turned on a circuit is completed which allows the electrons to flow. This is the electric current that does whatever work the device was built for, be it lighting a flashlight or powering an electric vehicle. Reversing the duty cycle will recharge the battery.

Current world demand for Lithium is about twenty thousand tonnes per annum and is expected to double in just five years. A large chunk of this is produced from brine wells in the Atacama, a high desert in Chile. The brine, with a relatively high concentration of Lithium, is pumped to surface ponds and allowed to evaporate – the Atacama is not only the driest place in the world but also one of the sunniest.

Trouble comes with the removal of the brine. This simultaneously lowers the water table for freshwater. In the driest place on earth, this is a big deal. Imminent local regulation is expected to reduce the allowed brine removal and therefore limit Lithium production. Other sources are being examined for Lithium production, most notably Arkansas.

A veritable ocean of brine exists under south Arkansas. This brine has been a source of crude oil and other industrial chemicals for years, especially Bromine. The Smackover formation originally produced mainly oil with Bromine from brine as a byproduct. Currently, Bromine produced in Arkansas represents the total US production and this is a third of the global supply.

A company is now exploring the possibility of producing Lithium as a byproduct of Bromine production. The Lithium is to be removed along with the Bromine, then the spent brine is re-injected. Bromine production in Arkansas is an eight hundred million dollar enterprise employing a thousand Arkansans. If Lithium production is practical it will add to both income and jobs in Arkansas.

Although all eyes are on Lithium as a battery component there are numerous other uses. Lithium grease, refereed to as White Lithium, is a valuable lubricant as it uniquely adheres to metal. Much Lithium is used in glass and ceramic manufacture. Finally, Lithium is valuable as a treatment for bipolar disorder.

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