The renewable energy market in Australia is booming. In 2016, around 17.3% of electricity generation was from renewable sources. More and more residential solar system owners are considering upgrading their system with a home energy storage. New solar customers often look for packages of a solar system with battery storage.
There are several reasons for this:
>> Storing electricity saves money. The price at which electricity is supplied is, on average, three times higher than the cost for which it is bought. Solar energy is generated during the day, but the peak consumption happens at night. Storing electricity in your own battery is a great solution for those who don’t what to buy it from the grid at higher rates.
>> Independance from the vulnerable grid. Having energy storage gives full control of electricity generated and consumed. It keeps power shortages and outages at bay and provides energy security.
>> Saving the environment. Not using electricity from fossil-fuel-fired power stations and using self-generated electricity from renewables makes everyone a climate change activist.
Sounds like you? Then energy storage is what the doctor ordered.
Even though current batteries show great saving opportunities and can help you during blackouts, battery development is continuously improving, bringing new features to energy storage.
This is one of the biggest arguments for those who prefer to wait before shelling out for a home battery.
So what exactly are we waiting for?
From lead-acid batteries to pumped hydro storage, from the variety of lithium-ion batteries to hydrogen fuel cells, there is immense scope in technology development and the future of energy storage.
The new innovations are moving towards more efficient, cheaper and safer batteries.
Let’s take a look at some of the most prominent technologies which we can expect to be the next ‘big thing’.
A flow battery, or a redox flow battery, is a battery in which the electricity is stored in liquid electrolytes or metallic salts, which have liquid positive and negative electrodes respectively.
These liquids with stored energy are kept in separate tanks and pumped to an electrochemical cell to generate electricity, with the change of ions between cathode and anode. During electricity storing the process reverses.
The common flow batteries on the market are Zinc-bromine, Vanadium redox (VRB) and Iron-Chromium (ICB).
In a Zinc-bromine redox flow battery, the electrolytes in both tanks are Zinc-bromine and this battery acts like an electroplating machine. Changes in phases on both electrodes in the form of metallic zinc and bromine generates and stores electricity.
The Vanadium redox flow batteries have vanadium in different states. The depth of discharge is really good for these batteries, but their bulky size is a matter of concern for residential purposes.
In Iron-Chromium redox flow batteries, the ion exchange between iron and chromium is the key to the charging and discharging of the battery.
For high demands, flow batteries are safer and more durable, with longer life cycles. Increasing the capacity can be easily handled by increasing the number of electrolyte tanks. Plus, these batteries can also undergo a full discharge, giving them an extra economic benefit.
On the other hand, the current technologies in flow batteries are expensive to install and have some environmental impacts from the vanadium and bromine.
A flow battery is a cross of battery and fuel cell, where it can perform functions of either. The electrolyte can be charged and discharged like a battery, while more electrolytes can be added to make it a fuel cell for a continuous supply. It is a two-in-one option in this case.
The latest innovation in flow batteries is from MIT, where the expensive metal salts used can be replaced by organic electroactive material from biomass: quinones. This innovation has the ability to make redox flow batteries greener and cheaper.
Solid State Lithium-ion Batteries
Lithium-ion batteries are a well-established form of energy storage technology from the past two decades.
They have high power density and are used in everyday devices like cell phones, laptops and even large-scale energy storage systems.
The liquid electrolyte is used in lithium-ion batteries, which helps in the migration of lithium ions in the battery, but this liquid electrolyte is combustible and heavy for transport.
A solid-state lithium-ion battery has solid electrolyte which makes it safer.
After a period of research on different combinations of electrolytes, Lithium phosphorous oxynitride Li3PO4 (LIPON) is seen as a potential solid-state technology, which can be enhanced to compete with liquid state lithium-ion batteries.
As you can see in the image, a liquid lithium-ion battery has a liquid electrolyte solution while the solid lithium-ion battery has solid electrolytes, making it compact and safer for the same capacity size.
Currently, solid-state lithium-ion batteries are used in small-scale applications.
These batteries can charge faster, last longer and occupy less space as compared to current lithium-ion batteries, and this can be the future of batteries when they become less expensive.
Gold Nanowire Batteries
At present, most of the batteries on the market are lithium-ion batteries, and the lithium inside the batteries corrodes in its lifetime. This makes batteries run for just a few thousand cycles and lose the ability to hold the charge.
But there is a possibility to run the battery more than 100,000 cycles, according to research by the University of California—for example, by using gold nanowires instead of lithium.
This technology uses a gold nanowire, no thicker than a bacterium, coated in manganese oxide and then protected by a layer of electrolyte gel. The gel interacts with the metal oxide coating to prevent corrosion. The longer the wire, the more surface area, and the more charge it can hold.
This is how gold nanowires with manganese oxide coating in electrolyte gel looks:
Gold tried in this technology is long-lasting but a costly proposition, hence other metals can be researched to build a battery which lasts a lifetime—and which is cheap too.
These batteries can run for many thousands of cycles—a big advantage if they’re affordable.
Generating electricity from water is quite a revolutionary idea. However, it’s not just water but a concentrated saline solution that is used as the electrolyte in saltwater batteries.
These batteries are easily recycled and are non-toxic. Aquion Energy has been pioneering the technology of saltwater batteries.
The Aquion’s battery has manganese oxide cathode, carbon titanium phosphate composite anode, synthetic separator and an alkali-ion saltwater electrolyte with stainless steel current collector.
The saltwater, acting as the electrolyte, has positively charged Sodium ions and negatively charged Chlorine ions doing their work of storing and discharging energy.
These are cheap because of the low-cost saltwater electrolyte.
These batteries are not power-dense due to using the saline solution as electrolyte, and that’s why this is the safest and cheapest energy storage technology to have the ability to transform the energy storage industry.
Use of salt water is the safest and cheapest way to store energy, but the bulkiness of the battery makes it more feasible for larger power plants.
Hydrogen Fuel Cells
Hydrogen is the most abundant element in the universe.
We do not have hydrogen as gas on Earth but as water in combination with oxygen, in hydrocarbons and other compounds.
A hydrogen fuel cell generates electricity when hydrogen combines with oxygen to give water and heat as by-products.
Hydrogen enters through the anode and is split into electrons and protons.
The electrons travel through the circuit, generating electricity, and the protons pass through electrolyte membrane where they attach to the oxygen at the cathode, generating water and heat.
Excess solar energy can be used to split water into oxygen and hydrogen, and hydrogen can then be stored and transported to generate electricity from a fuel cell.
With more research into this technology, it has the potential to disrupt the renewable energy market.
These fuel cells are highly efficient, do not require recharge, are highly scalable and can run continuously.
On the other hand, these are very costly and require hydrogen as a fuel, which is not readily available unless made.
There are a number of energy storage technologies still being researched and tested before they can form an integral part in renewable energy generation.
Energy storage will be essential in years to come as more renewable energy technologies are deployed on the ground and much more rigid and secure grid infrastructure is required. The variability in generation from technologies like solar and wind require this change. Energy storage will give stability to the grid and security to its owners.
After lithium-ion batteries, the next big thing to take the position in the large-scale energy storage will be hydrogen fuel cells and saltwater batteries because of their reliability and their non-toxic nature.
When the electricity generation is small scale, such as in a home, solid-state lithium-ion batteries will take up the lead because of their compact design and safe use.
If you want to see how much solar or battery storage could save you over the next 5 years, then take our solar saving calculator quiz below!
Or talk to an Instyle Solar expert about the best solutions for home energy storage or PV-panels.
Otherwise, head back to the solar blog to find even more great educational content.