Energy Storage

In the energy sector, fossil fuel sources have been the main energy source due to their relatively low price. However, our energy demand is predicted to rise in the future, and we can no longer rely on finite and polluting energy sources. Driven by higher energy demand in 2018, global energy-related CO2 emissions rose 1.7% and this contributed in environmental damage. Hereby, alternative energy sources will be a main focus to prevent further climate change effects on our planet. In the last decade, we have seen a positive shift towards expanding our renewable energy capacity, both on a local and global level.

Wider adoption of alternative energy sources depends on even more efficient renewable technologies and restructuring of the electric utility industry. With the use of renewables, generating clean energy is possible on a domestic level, with technology such as solar panels, heat pumps, and biomass boilers. In order to utilize energy that is mostly weather or time-dependent to its full potential, we are yet to come up with better energy storage solutions.

Some promising storage options:

1. Hydrogen Storage

In the future, hydrogen will be a driving energy source. Currently, the majority is produced from fossil fuels. However, surplus alternative energy is also used to produce hydrogen gas. Uses are versatile - hydrogen gas can be supplied to the natural gas grid, or by using fuel cells to be reconverted to electricity.

Hydrogen might be widely used in the transportation sector, when we are able to come with less costly solutions for wider implementation of such alternative energy sources. Hydrogen has the highest mass of density of any fuel, making it better for distribution and storage. Its stable chemistry also means that it can hold energy better than any other medium. In the future, creating a supply and storage infrastructure will enable a more efficient use of hydrogen. Future plans for hydrogen include building an underground storage system where surplus wind energy, for instance, can be transformed into hydrogen through electrolysis.

2. Pumped Thermal Electricity Storage

One more promising storage option is pumped thermal electricity storage. This relatively new technology has been around for about ten years, and is currently being tested in pilot plants. Pumped thermal electricity storage works by turning electricity into heat using a large-scale heat pump. This heat is then stored in a hot material, such as water or gravel, inside an insulated tank.

When needed, the heat is then turned back into electricity using a heat engine. These energy conversions are done with thermodynamic cycles, the same physical principles used to run refrigerators, car engines or thermal power plants.

3. Geothermal Storage

There are two basic types of geothermal energy. One is deep geothermal, coming from the Earth’s core, and the other is shallow geothermal, the solar energy stored in the ground. Deep geothermal energy utilization usually involves drilling very deep boreholes near natural cracks, while shallow geothermal energy (typically around 0-300 m below the surface) is available everywhere.

4. Battery Storage

Batteries are an energy storage technology that uses chemicals to absorb and release energy on demand. Lithium-ion is the most common battery chemistry used to store electricity. Coupling batteries with renewable energy generation allows that energy to be stored during times of low demand and released (or dispatched) at times of peak demand. Unlike many other forms of energy storage and generation, batteries are particularly valuable because they provide flexibility. They can respond faster than other energy storage or generation technologies, and help maintain grid stability by turning on and off in fractions of a second.

A battery with unbeatable performance, high energy density, low costs and environmental impact as well as longer lifetime. We might be lucky enough to see these batteries in markets sometime in the future. A battery being developed right now in a lab will take at least 10 years to become commercially available. The battery needs to be tested rigorously to ensure operational safety, and then comes the challenge of achieving economies of scale.

What the future looks like?

E-mobility is expanding, and we now see electric cars, bikes, scooters and kick bikes in the streets. Soon these may be joined by more fuel cell vehicles running on hydrogen. Utilization of all of these vehicles will be extended beyond their intended use as means of transport to also include energy storage: they will charge when renewable energy is abundant in the system and feed energy back into micro-grid’s battery when needed. Such vehicle-to-grid and vehicle-to-building systems may become more common when regulatory barriers are lifted. With portable storage with safer solid-state batteries and hydrogen bottles, our phones will never again run out of batteries. The use of phase-change materials that store latent heat in self-warming clothes will also make it more comfortable to be outdoors in winter.

The future city is a storage city: a smart city where energy is needed on the go, a city where a large share of energy comes from renewable sources, a city where the internet-of-things allows communication between appliances and infrastructure. A future with battery-powered gadgets and vehicles, appliances, fuel cells and skyscrapers made of hydrogen-produced steel, thermal grids for heating entire neighborhoods and cooling supermarkets.