Energy for Life
Our lifestyle relies on energy. Mobile and in a fixed location, it is energy that moves us, provides us with light, provides the right temperature, and applies force to anything we want. But how to get this precious good to where we need it? As climate change gets more and more in focus, a cleaner energy mix replaces carbon-based power.
The two main energy forms, oil and electric power, have different features. Oil has a high energy density. It can be stored without loss over a long period of time, but it has to be handled as a hazardous liquid. Electricity can be transported with wires, astoundingly thin for the power they transport. But electric power has to be spent the same moment it’s produced. Yes, batteries exist, but if we’re talking about grid-scale energy storage, ordinary batteries won’t do at all. Atomic power plants have a singular capacity and enough power to support basic consumption at any time. Using coal, gas, or crude oil to produce electricity is also an option. They are heavily used at peak-load plants, as they can be started and stopped easily.
Electric power consumption varies over the day with a peak when people start cooking before lunchtime or more and more when e-cars return home to be recharged in the evening. Demand management helps control the peaks by offering off-peak tariffs or smart grid solutions to turn off some devices in peak times. But the problem of how to save energy on grid scale persists.
Look around. Energy can be stored everywhere. It’s stored in a height difference before liquid flows. Molten salt and compressed air store it. So many things store electric energy.
And another clever way to save electric power for later use is to convert it to hydrogen, although doing so still isn’t efficient. The oil and gas industry sees its future in providing liquid hydrogen to power cars. In their view, the best way to drive long distances is an electric car, powered by a fuel cell that runs on hydrogen. It worked on the moon missions. Time to bring it down to earth.
Solar and Wind
We’ve talked about photovoltaics for decades. But recently, solar energy reached a minimum cost. It’s cheaper to produce electric power from the sun than from a nuclear reactor. Financial considerations lead to the installation of 120 GW of solar capacity worldwide every year. That’s roughly the capacity of 120 nuclear power plants added per year. It’s a real game changer.
Wind energy is used widely as well. Production follows the weather pattern. Like solar, wind increases the need for massive electric power storage.
Countries that have mountains have the opportunity to store potential energy. Water can be collected in lakes on a mountain. When released, it drives a downhill turbine. The bigger the height difference, the greater the capacity.
In the last decade, power companies started to convert those hydropower plants to using excess energy to pump water back up the hill. One of the finest engineering examples can be found in the Austrian federal state of Vorarlberg, near the city of Gaschurn in the Montafon. You don’t see the new pumps, which have been installed inside the mountain.
Power plants like this are common now. They have a very high response time and can be used for peak loads in production and consumption. That’s almost like a battery. They only take two minutes to start up from zero to maximum power, and a minute to reverse the energy flow.
Without water, gravity can still help. Take abandoned coal mines. A mineshaft a mile deep can make a perfect battery. A heavy weight runs down the shaft, the cables connected to a generator to gain electric power. It can be pulled up again to store energy.
Without such shafts, there might be demolition waste. Formed to weights, it can be lifted with a crane, storing electricity as gravitational energy. That also makes a perfect industry-grade energy storage system, along with a nice crane ballet.
All those concepts are big and create single points of failure. A different way of thinking is to decentralize energy production and storage, and to use the power grid as a market and distribution network in both directions. Hydrogen production could be decentralized. Put a production container at each gas station. It will consume local solar or wind power to produce hydrogen. Petrol tankers will be needed only to balance storage levels. Another form of decentralized energy production is small hydropower plants, like vortex turbines, that make use of creeks. A height difference under 1 meter supports up to hundreds of houses with electric energy.
Many people have photovoltaic cells on their roofs to produce clean power. Houses need most energy in the morning, in the evening, and during the night, so where to save it? The most common form will be a mixed installation. Being connected to the grid plus adding some electric energy from your roof. What you use in your home stays there and reduces your energy bill.
The simplest and most efficient form to save electric power locally is to heat up water in a boiler. In colder regions, you need high-temperature water anyway, so producing it during daytime and saving it for the night is a good idea. If you use a heat pump, you can get five times more heat than you put electric energy in.
Charging your electric car also makes sense, if you don’t charge it while at work. Charging with solar cells on an office building during daytime makes much more sense. At home, you can save your energy in a used e-car battery. Tesla offers such storage systems, which require a room where you can install a 200 kg object.
Some battery concepts use salty liquids to save electric power. Electrons separate through a membrane between two liquids and remain in storage tanks, one part charged positive, the other negative. This concept works in household dimensions and on an industrial scale.
Another easy solution is to sell your spare energy to the power grid. It will be used somewhere else, maybe in a pump storage plant as in Montafon. You won’t get much money for your spare energy, and during the night you might have to buy it back for a much higher price. Since the sun charges you nothing, you only gain money. The questions are how much to invest and whether you care about a return on that investment.
If you decide to install a battery, you need to buy and maintain the cells. I decided to go 100% electric for cooking, heating, and mobility. I also bought shares of a small, local hydropower plant that supplies me with electricity.
I’ve learned from the big players that energy is everywhere. Solutions are different for each location. Keep your eyes open. Consider alternatives to standard solutions. An eco-friendly one will be cheaper in the long run.
Franz Ablinger (* 1967), electrical engineer, artist and founding member of Vienna-based art collective monochrom, computer historian with a doctorate in philosophy. Likes to tinker with anything interesting.