As heavy industries around the world continue to strive for cleaner, more efficient, and environmentally friendly energy storage, plenty of options in addition to cogeneration, or combined heat and power (the use of a heat engine or power station to generate electricity and useful heat at the same time), are emerging.
Energy storage, while still a relatively expensive endeavour, is crucial as production of renewable energy is intermittent—when the wind blows or the sun shines.
The cost of producing electricity from solar and wind energy has significantly decreased in recent decades, and because of this, according to U.S. Department of Energy projections, energy sourced from renewables will continue to show the highest rate of growth through 2050.
Researchers at NREL (National Renewable Energy Laboratory) calculate that there is the potential to triple the nation’s current capacity for storing renewable energy by 2050, with several emerging technologies that could help make this happen—the first being batteries.
We all take batteries for granted, but there are many opportunities for improvement. High-capacity batteries with up to 10-hour discharge durations may be useful for extending the range of electric vehicles or storing solar energy throughout the day. New estimates indicate that by 2050, up to 100 gigawatts’ worth of these batteries will likely be built, resulting in the viability of renewable energy improving significantly.
Limited resources of lithium and cobalt—currently necessary for producing light, potent batteries—are one of the main challenges. By 2050, almost all of the world’s cobalt reserves and about 10 percent of the lithium reserves are predicted to be exhausted, while the Congo, where around 70 percent of the world’s cobalt is mined, has problematic labour practices.
To address these concerns, in addition to designing batteries using different materials, scientists are striving to create methods for recycling these lithium and cobalt batteries. Tesla intends to introduce cobalt-free batteries in the coming years, while other companies want to replace lithium with sodium, which has many of the same properties as lithium but is far more plentiful and could benefit technologies for storing renewable energy.
Increasing battery safety is another priority. Electrolytes, the liquid or gel substances that enable an electric charge to flow from the battery’s anode (negative terminal) to the cathode (positive terminal) are one area that could use improvement as they can be highly volatile and flammable, causing fires and explosions should they leak.
Batteries can also be more expensive than other renewable energy storage options.
Concentrated solar power plants employ mirrors to focus sunlight, which heats hundreds of tons of salt to the point of melting. In a similar way to how coal or nuclear power is utilized in conventional plants to heat steam and drive a generator, this molten salt is used to power an electric generator. Additionally, these heated materials can be stored and used to generate electricity on sunless days, which enables continuous use of concentrated solar electricity.
This concept can also apply to other forms of power generation: for instance, heating salt with electricity generated from wind energy for use on windless days.
Solar power concentration still has a high cost, however, needing to improve its efficiency to compete with other energy generation and storage technologies. Increasing the temperature at which salt is heated is one way to do this, allowing for more effective energy generation.
While concentrated solar power plants and batteries can be used to produce and store renewable energy for a limited time, utility companies need to store significant amounts of energy for long periods, which is where hydrogen and ammonia, two renewable fuels, come into play. When wind turbines and solar panels are producing more electricity than the utilities’ customers require, utilities could produce these fuels with excess energy and store them there.
When it comes to hydrogen, thermal, and distributed energy storage, all pose their own advantages and challenges.
Hydrogen energy storage requires the mass production of hydrogen. This can be achieved with electrolytic hydrogen production, where water is split into oxygen and hydrogen through electrolysis. However, the most common method is a high-temperature method known as steam reforming using a hydrocarbon fuel such as diesel or natural gas, and steam to release the available hydrogen.
Many industrial processes use hydrogen, including the production of glass, fertilizer, steel, and chemicals. Due to environmental laws and consumer preferences, however, all of these companies urgently need to cut their carbon footprints.
Hydrogen can be used to generate electricity, heat, or fuel an automobile by using renewable energy inputs, and electricity can be produced when necessary by using the hydrogen that’s been stored. It can also be applied to other energy-demanding fields including the gas grid, fuel for vehicles, and industrial processes.
However, hydrogen energy storage currently costs more than fossil fuels, and most of these hydrogen-storage methods are still in the early phases of research. Extremely little energy can be produced by fuel cells from hydrogen for powering business or residential buildings.
The market for hydrogen energy stored in liquid form is constrained because this process involves considerable capital expenditures through the high insulation costs necessary to prevent evaporation and ensure safety around this explosive substance. As a result, the time and money required to charge and discharge hydrogen in these systems as well as the associated process costs are substantial.
Thermal energy storage (TES) involves a storage medium heated or chilled to store thermal energy, which can then be used for power generation as well as heating and cooling. TES equipment is very helpful in industrial and construction activities, employing a variety of techniques to store usable thermal energy in insulated repositories. A TES system typically includes a tank storage medium, a built-in refrigerated system or compact cooler, as well as pipes, pumps, and controls.
Again, the cost is an issue. While the TES system can securely store enormous amounts of energy, and its normal self-loss is negligible (0.05 to 1 percent), the price of a solar energy storage system varies depending on its use, size, and heat insulation method.
Phase transition materials and thermochemical storage-based thermal storage methods are often more expensive than the storage capacity they provide.
A pre-packaged option for storing energy for later consumption is a distributed energy storage (DES) system. The DC-charged batteries and the bi-directional inverter are the two crucial components of the system with equipment contained within a sturdy chassis that’s suitable for shipping. Lithium-ion batteries and cutting-edge technology are used in distributed energy storage systems to quickly collect and release extra power, resulting in a variety of advantages for users.
The market for distributed energy storage was estimated at $11.70 billion globally in 2021, and by 2027, it’s anticipated to grow to $19.20 billion. By providing smart grids and related services, distributed energy storage is a crucial part of updating the entire energy system, and if used to boost reliance on renewable energy sources, there will be considerable climatic benefits.
However, electric cars powered by distributed energy storage have a significant environmental impact. Additionally, distributed energy storage systems have a high initial investment cost and significantly greater ongoing maintenance costs. The increasing cost of the essential minerals required to make the batteries, the ongoing Russia-Ukraine conflict which has disrupted the supply chain, and COVID-19 lockdowns in some parts of China have all prevented the market from growing.
Ultracapacitors too offer a compelling argument as a vital technology for both environmental and financial reasons, especially in light of the growing focus on climate change and sustainability.
In recent years, the use of ultracapacitors, also known as supercapacitors, double-layer capacitors, or electrochemical capacitors, has grown significantly. Although they can be compared to a hybrid of a battery and a typical capacitor, they’re not the same thing.
The name “ultracapacitor” refers to a type of capacitor with a very high capacitance—the ability of a component or circuit to collect and store energy in the form of an electrical charge—in comparison to other types. Ultracapacitor cells feature a positive and negative electrode separated by an electrolyte, just like a battery, however, they don’t store energy chemically as batteries do; instead, they do so electrostatically.
While ultracapacitors don’t store as much energy as a battery of comparable size, they have one important advantage. They don’t need a chemical reaction to discharge their energy and no physical or chemical changes take place, so they can do so far more quickly. This also allows them to be recharged countless times with little to no deterioration—in excess of one million charge / discharge cycles—another fantastic advantage.
Supercapacitors are frequently utilized in applications that call for numerous quick charge / discharge cycles as opposed to long-term compact energy storage, like automotive booster packs and power banks.
Today, most of these forms of energy are produced through incredibly inefficient processes from natural gas or other non-renewable fossil fuels, so finding ways to make the procedure effective and affordable is the key to producing infinite, entirely renewable energy as a huge potential benefit.
While the energy sector is under increasing pressure to lower the cost of renewable energy sources while also boosting adoption rates, start-ups and scale-ups are creating a variety of solutions for both consumers and energy producers with technologies that lower the cost of solar and wind power, boost energy storage capacity, and boost battery efficiency.
Storage is ultimately an enabling technology. When used wisely and with the environment in mind, consumers can save money; reliability and resilience can be increased, energy sources integrated, and environmental effects lessened, yielding long-term benefits for years to come.