Tag Archives: batteries

Sustainable Energy is Booming

By late in 2019, the combined electricity produced by grid-connected wind and solar photovoltaics represented 10% of the total production. And the share of these intermittent but sustainable energy sources continues to grow. Energy production from coal is in free fall, despite the current administration’s attempts to favor it.

A constant refrain from detractors is intermittent sources such as wind and solar require expensive backup when the wind isn’t blowing or the sun isn’t shining, and therefore can’t be a serious part our electricity production until such batteries or other energy storage systems are available. That however is just not the case. It is estimated that a national network of electricity production and distribution can utilize up to about 30% wind and solar without the need for additional storage to back up the intermittency.

Consider what happens when one of our local nuclear reactors goes down to refuel. Is there another reactor on stand by to make up for the power not produced during the refueling? No, of course not, there is plenty of “slack” in the system to make up for that not produced during the refueling.

Other factors help balance the power from wind and solar. Solar is well matched to demand. Demand is higher during the day when solar panels are producing, and lower at night when the power from solar panels isn’t needed. Without the input from solar panels, a power company may have to buy power from sources that are on standby. Some power companies utilize time-of-day pricing, charging less at night when power is relatively abundant, and more during the day when demand is higher.

Wind and solar also balance each other seasonally. As sunlight passes through the atmosphere light is scattered and less reaches the earth. The lower the sun angle the more atmosphere it must pass through. Solar panels are more productive in the summer due to the the higher sun angle. A higher sun angle means less scattering of the light and more sunlight striking the panels.

Conversely, wind turbines are more productive in the winter. There are two reasons. Wind is generated by temperature differences between locales and the differences are greater in the winter, hence higher wind speeds. Additionally, colder air is denser. More power will be generated by the denser air at a given wind speed.

One final balance is that the sun shines during the day (duh) so solar power is available during the day, but wind speeds are greater at night. Wind and solar are both intermittent but complementary, both daily and seasonally.

As intermittent energy sources grow there will be a need in the future for energy storage and that constitutes a huge area of research. Electrochemical batteries, pumped water storage, other gravitational energy storage systems, compressed air, flywheels, and on and on. The future will be powered by the wind and the sun, cleanly without the need for fuel, and without waste disposal issues.

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

Lithium

A couple of decades ago and without having taken at least a high school chemistry course most would not have heard of Lithium, nor use it in their daily lives. Now however it dominates the battery world. Disposable Lithium metal batteries power all sorts of devices which require the packing a lot of power in a small space . In addition to AA and AAA batteries, Lithium metal batteries power virtually all the “coin” batteries in small devices such as hearing aids and watches. Lithium metal batteries also have an illicit use as a reagent in the synthesis of methamphetamine but that is another story.

Lithium metal batteries pack about twice the punch as Lithium ion batteries for a given size. More important for many applications is the fact that Lithium ion batteries are rechargeable, greatly increasing their utility. Everything from cell phones to plug-in hybrids (electric cars which can be charged at home or work) utilize the rechargeable aspect of lithium ion batteries.

Lithium is a metal but 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 it’s charge to weight (and volume) ratio. Lithium metal 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 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 which does what ever work of a device was built for, be it lighting a light bulb or powering an electric automobile.

As the reservoir of electrons is depleted the battery loses power. Rechargeable batteries are capable of reversing the loss of electrons by pushing electrons back into the battery.

Rechargeable batteries are at the heart of numerous university, government, and private research facilities for two obvious reasons. First, electric powered transportation is the future but contemporary batteries have a limited range. Equally limiting is the long recharge times required. To replace internal combustion engine powered cars, battery powered electric cars and going to have to have a several hundred mile range and a few minutes recharge time. That is a tall order.

So is there enough Lithium out there to meet the increasing demand? Do we have supplies here in the US or do we have to buy it from other countries? Can we afford it? All valid questions. Lithium is present in the earth’s crust at about 20 parts per million (PPM.) This doesn’t sound like much but it more than more commonly known metals such as Lead and Mercury.

Currently we import about 80% of our Lithium needs, but recent prospecting has turned up brine deposits in Wyoming which may provide for our need for sometime into the future. Ultimately the world’s richest deposits of economically recoverable Lithium are in the Atacama desert on the Pacific coast of Chile. Unrelated factoid – the Atacama is the driest place on earth.