A recent article on Harvard Business Review, suggested that in order to increase our productivity we should shift our focus from managing our time to managing our energy, emphasizing the importance of conserving energy for when you most need it.
Although we have gotten better and better over the years at coming up with more efficient ways to produce energy, we haven’t gotten any better at storing that energy. Yes we might have more efficient engines, solar panels and wind turbines, but during peak hours most of the energy is wasted due to a lack of efficient energy storage solutions.
The same is true on a personal level, we have access to power bars, energy drinks, coffee at every corner and more sugar than our bodies can handle, but all this easily available energy has hindered our bodies abilities to recover the energy it stores as fat. In this post I will not go into details about how to recover energy from your body by burning fat (there are other people better qualified to give you advice on that) Instead I will present the basics of electrical, mechanical and thermal energy storage and the most revolutionary devices available on the market today.
Energy can be stored in many forms: thermal energy, compressed air, using a flywheel, in pumped hydro-power plants, in solid batteries or in flow batteries. In this article I will go into details about the pro’s and con’s of each option. And if you stay with me until the end of the article you will discover also the latest technological developments in energy storage solutions, including some surprising tech like liquid metal batteries or batteries made from food waste.
Storing energy as compressed air is very straightforward, you use excess energy to compress air and then use the mechanical force of the air to power a generator. The first system was developed in 1870 and the first large commercial application 100 years later in 1970.
A flywheel is not a wheel that flies, as I first thought, but a mechanical device that stores rotational energy. When you think of a flywheel think of a potter wheel, where the artist presses from time to time a pedal to keep the large plate on top rotating. We all have flywheels in our car’s engine, this is what keeps the engine running smoothly and prevents burst of power when there is an ignition in the fuel chamber. Flywheels can also be applied to bicycles, storing energy when you are driving on a straight line and releasing it when you need an extra burst of power.
This is one of the most established large scale storage solution. It uses gravity to cascade water through a turbine to produce electrical energy. The water is pumped in the reservoir when there is an excess of energy and released when there is a high energy demand.
Romania plans to build a 1000MW pumped hydro power plant at Tarnita, to store excess energy from renewable energy sources like wind and solar.
Thermal Energy Storage
Similar to keeping your coffee hot in a thermos, thermal storage systems save energy from heat or cold for use at a different time. Traditional materials that are good for heat storage are objects with a large mass: large rocks or salt blocks, clay like the one used to make fire places or even concrete. Earth homes, that have 3 sides covered with clay and the south side made of large windows designed to capture light and heat from the sun during the day, use this principle to store large quantities of heat during summer days and release them slowly during the winter time.
One example of a large heat storage system found in almost every city, that causes us great discomfort, is a poorly insulated concrete apartment block. This accumulates heat during the day and releases it during the night, that is why in a hot area this buildings can be extremely uncomfortable.
Heat storage polymer
Materials that can store heath have been around for ages, but researchers are working on some exciting new developments in this field. At MIT, professor Jeffrey Grossman, postdoc David Zhitomirsky, and graduate student Eugene Cho, are currently developing a thin transparent polymer film that can store heat during the day and release it on demand. This materials could be used in the future in our clothes or on a car windscreen to prevent them from freezing.
Matt Scullin also realized the potential of collecting heat and converting it into energy, so he created a panel that does just that. He uses thermoelectric materials to turn waste heat into energy, similar to a solar panel that converts energy from the sun into electricity. Scullin found a new class of thermoelectrics developed at Michigan State University made from tetrahedrite that can do a better job than traditional thermoelectric materials for less money.
The solid batteries
This is the most common technology out there. We all have solid batteries in our phones, our stereos or our remote controls. Alessandro Volta is credited with the invention of the first solid batteries in 1800, and along with it the entire field of electrochemistry. To make it simple a solid battery is a device that converts stored chemical energy into electrical energy by using one or more electrochemical cells. Although the solid batteries has been around for 200 years, and the new lithium-ion batteries are more efficient than traditional ones, (we all know that the Duracell rabbit can run for hours or that Tesla launched not long ago the Power Wall), the solid batteries industry hasn’t seen any ground breaking innovation, until the recent discovery made by the Karlsruhe Institute of Technology.
The Future of Energy Storage
Recycled batteries from rotten apples
Researchers at the Karlsruhe Institute of Technology in Germany found a way to transform rotten apples into a hard carbon material for sodium-ion batteries, solving two problems in the same time: reducing food waste and revolutionizing the way we will store energy in the future. The new batteries could be used for improving our grids but also to replace the current batteries we use in our phones, laptops or tablets. According the the institute: “Sodium-ion batteries are not only far more powerful than nickel-metal hydride or lead acid accumulators, but also represent an alternative to lithium-ion technology, as the initial materials needed are highly abundant, easily accessible, and available at low cost.”
Molten metal battery
“Donald Sadoway of materials science and engineering (right), David Bradwell MEng ’06, PhD ’11 (left), and their collaborators have developed a novel molten-metal battery that is low-cost, high-capacity, efficient, long-lasting, and easy to manufacture—characteristics that make it ideal for storing electricity on power grids today and in the future.” MIT.
These batteries are designed to store energy for large scale applications. The battery consists of molten metals that can naturally separate to form two layers of electrodes separated by a molten salt electrolyte. The materials used are low cost and earth-abundant, not like the ones used in lithium-ion batteries, and the first tests confirm that the liquid battery operates without losing significant capacity or mechanically degrading. The inventors are determined to bring the technology to the market and they set up a company for this purpose http://www.ambri.com/
Aqueous Hybrid Ion (AHI) Battery
Jay Whitacre, winner of the 2015 $500,000 Lemelson-MIT Prize has invented a reliable, environmentally-benign and cost-efficient energy storage system. This battery can be used in combination with solar and wind energy systems, to store high amounts of energy at a significant low cost per joule. The AHI battery is developed using abundant and inexpensive resources like water, sodium and carbon. Whitacre founded a company, Aquion Energy, to help bring the technology to the market and he already has fully commercialized the battery in many locations including Australia, California, Germany and Malaysia.
“In the search for large-scale electrochemical devices, much attention has focused recently on systems using hydrogen and bromine.“
This combination can offer some attractive features: The materials are inexpensive, readily available, abundant and Bromine is also very “electro-negative,” meaning that it really wants to pick up another electrons, in this case provided by the hydrogen. Chemical reaction between them therefore occurs extremely rapidly, but there’s a catch. If the hydrogen and bromine react spontaneously, the energy of the reaction will be wasted as heat. To prevent this most bromine batteries are equipped with a membrane, unfortunately this membrane gets damaged over time by the chemical reactions inside the batteries.
Buie, Martin Z. Bazant, professor of chemical engineering and mathematics, and William Braff PhD ’14, improved the existing research on bromine batteries, and developed a new prototype that replaces the membrane with an electrolyte — hydrobromic acid (HBr). As a first test of the membrane-less hydrogen bromine concept, the team designed and built a small demonstration cell. The prototype achieved at room temperature and pressure a maximum power density of 795 milliwatts per square centimeter (mW/cm2). According to the MIT researchers, that is comparable to the best hydrogen bromine cells with a membrane, and it’s two to three times better than any previous membrane-less design using any chemistry, so there is hope for the future.
Which tech do you believe will be the one to revolutionize the way we store energy in the future? We would love to hear your thoughts in the comment section below.