The realities of adverse climate change seen in more frequent extreme weather events are pushing for faster adoption of green energy solutions. Renewable energy sources have been developed for several decades. But the biggest hindrance to faster adoption is storage. High-capacity energy storage is key to adopting green energy because it will match power generation and demand. It will solve the problem of intermittency, which is the drawback of green energy generation.
What is a Green Energy Storage System?
Green energy is renewable energy that does not cause a negative impact on the environment. It differs from fuel energy, which is nonrenewable and has several negative impacts on the environment. This damage to the environment includes:
- Environmental degradation during the extraction and processing of fuels like coal. Forests are cleared to make way for mining and drilling.
- Greenhouse gas emissions from the release of carbon-type gases into the atmosphere from burning organic fuels. It has caused adverse climate change in extreme weather events, droughts, and global warming
- Pollution of land and water resources from improper disposal of the byproducts of fuel systems
A green energy storage system generates renewable energy at minimal impact on the environment. The best example of green energy is the solar energy system. The sun shines every day and is not expected to stop shining soon. This energy supply is infinite if it can be tapped. All that is needed to tap solar energy are photovoltaic cells. There are no impacts on the environment in tapping and using this energy.
What are the Green Energy Storage Solutions Today?
There are several green energy storage systems today that are evolving to meet the needs of green energy in the future:
Pumped Hydro Storage
Pumped hydro systems use water reservoirs as stores of potential energy. It is the most prevalent energy storage system in the world. Today’s pumped hydro stations are getting smaller to serve mini grids.
Thermal Energy Storage Systems
Thermal energy systems collect, store energy as heat or cold forms and generate electric power when there are changes in temperature. Thermal energy storage systems in use today include:
- Molten salts thermal storage
- Chilled water thermal storage
Electro-mechanical energy storage systems
These systems store kinetic or gravitational energy, which is turned into electric energy with the help of the movement of mechanical devices. They include:
- Flywheel energy storage
- Compressed Air Energy Storage
Electro-chemical Energy Storage Systems
These systems store energy in chemical form. They generate electric power when chemical reactions occur as the compounds and elements interact. These systems include:
- Rechargeable batteries
- Flow batteries
- Fuel cells
The Potential of Solar Energy Solutions
Solar energy presents by far the biggest potential in renewable energy generation and storage. Theoretically, the solar energy harvested from the Sahara desert alone would be enough to power the entire world without the need to cultivate new energy sources.
However, today’s solar energy implementation is yet to go on a very large scale. In South East Asia, solar energy is mainly used as a secondary power source, more so in residential settings. But governments have realized the massive potential of solar energy. For example, Singapore has set a target of 2 Gigawatts solar power by 2030. It is part of the 4-stage plan to switch to clean energy in the long term.
Solar energy systems are seeing accelerated adoption because of the dropping prices of solar panels. In 2010, the cost of solar energy was around $1,000/kWh. In 2020, the price had dropped to around $200/kWh. The efficiency of solar panels to convert solar energy into electric power has also gone up to around 24% from less than 15% 20 years ago.
Solar energy systems have the easiest path to generate green energy. There is plenty of space to install solar panels on rooftops, on the sides of skyscrapers and on ocean water. Higher efficiency solar panels will require smaller space.
The Promise of Battery Technology in Green Energy
Batteries are the mainstay of energy storage today. Lithium batteries make up the biggest share of the battery market. They are compact, portable and scalable, which makes them suitable for different applications. Newer battery technology is seeking to improve lithium batteries, or use other materials to make batteries with higher capacity and longer life.
Some of these newer battery technologies that hold good promise for next gen green energy storage systems include:
Lithium-Sulfur (Li-S) Battery
This battery will use sulfur and lithium electrodes. This technology has shown to have four times more energy density than equivalent Li-ion batteries. This battery will have a longer life than today’s batteries.
Lithium Tungsten Battery
Nanobolt lithium tungsten batteries seek to maximize the surface area for ion attachment such that charging and discharging is faster, and the capacity is increased. The battery operates at a miniaturized level (nanotubes) to make it scalable in different applications.
Zinc-manganese oxide batteries are being seen as very viable for large-scale applications. Zinc and manganese are cheaper and more available than lithium. The projected costs are $100/kWh in large-scale applications.
Gold Nanowire Battery
Gold nanowire gel electrolyte will replace liquid electrolyte with gel. There are gold nanowires covered with manganese dioxide and immersed in electrolyte gel. This battery goes through 20,000 charging cycles without losing energy density, as compared to 6,000 in conventional li-ion batteries.
One of the biggest drawbacks of li-ion batteries is the risk of flammability of the electrolyte, which becomes more real in large-scale applications. The organosilicon electrolyte is a good alternative to make lithium batteries more stable for large-scale use. Lithium nickel manganese cobalt oxide batteries using organosilicon electrolyte have achieved 400 Wh/kg energy density as compared to 200Wh/kg for conventional Li-ion batteries.
Solar Battery Role in Green Energy
While solar energy is abundant, it is intermittent. It peaks when the sun is brightest and goes off at night. For wide adoption of solar energy, power generation must match power demand. Solar battery installations will enable storage of energy tapped at peak power generation. The power is released into the power grid to match demand when necessary. Large-scale batteries are already in use in some places.
For next gen green energy storage solutions to work, energy storage technology must match green energy storage solutions. Solar energy and battery technology will play a huge role in the switch to green energy.