Energy storage systems enable the ability to store excess renewable electricity for use at a later date. For instance, when it comes to solar power, energy storage is used within off-grid or hybrid solar power systems, which require power to be used at night when there is no sunlight or as a backup solution during power outages.
There are various technologies for energy storage depending on how energy is stored for later use, including but not limited to pumped-hydro, compressed air, flywheels, batteries, and thermal energy storage. In addition, new energy storage technologies are currently under development such as flow batteries, supercapacitors, and superconducting magnetic energy storage. You can learn more about these energy storage systems at EPA.gov.
Batteries as energy storage technologies are becoming increasingly important to the power industry and for powering electric vehicles. One of the batteries that have become widely used is the lithium-ion battery which has been implemented in many locations, especially in the USA. The Tesla Gigafactory is one example where batteries are produced for energy storage systems for solar PV systems and electric vehicles. As such, solar produces clean energy during the day and Tesla’s Powerwall can store energy to power your home at night or during an outage.
When it comes to batteries, there are various types of battery storage systems that use different technologies based on chemistry that enables energy storage capability. For instance, solar batteries used to store excess solar power include four (4) types of batteries, including AGM, GEL, Flooded, and Lithium-ion batteries. These solar batteries use different chemistry or chemical composition to enable energy storage capability. For example, lithium-ion batteries as a group have the advantage of high specific energy as well as high energy and power density relative to other battery technologies because of their chemistry. Lithium-ion batteries usually have a cathode made of a lithium metal oxide, while the anode is often made of graphite.
The advantages of Li-Ion batteries are that they last longer, are more efficient, have a greater energy density, and require no maintenance compared to traditional lead-acid batteries. Great applications for li-ion batteries include backup energy storage for residential and commercial places. Lithium-ion batteries are also used by installers and power utilities to ensure a long-term, hassle-free, emergency backup power supply. In general, energy storage has become an important component for variable renewables such as solar and wind to enable excess power to be stored in batteries when solar or wind generation is high to be later used when power generation is low.
Against this background, this blog attempts to capture about four (4) reasons why energy storage systems are increasingly used with renewable energy systems:
1. The reducing cost of energy storage systems and the increasing demand of variable renewable energy
Because of the increasing demand of energy storage technologies, their cost has been falling rapidly and by the year 2030, IRENA estimates that the installed cost of battery storage systems could fall by over 50%. The declining cost in the wind and solar and the increased focus on adding renewables to the grid is driving the interest to lower the cost of energy storage. For instance, the price of lithium-ion batteries has fallen by about 80% over the last five years according to the National Renewable Energy Laboratory (NREL) enabling the integration of storage into solar power systems. Also, there has been a tremendous increase in the amount of energy storage that is been deployed. A market research firm, Wood Mackenzie Power and Renewables has forecast that energy storage systems will increase to top 5.4 gigawatts and the market value is forecast to increase from $720 million today to $5.1 billion in 2024.
2. To increase solar and wind penetration in the grid
With the increasing penetration of renewable energy into the grid, energy storage has become an important component for variable renewables such as wind and solar. Utilities are using energy storage systems to counter the intermittent nature of variable renewable energy. Energy storage systems store excess electricity during off-peak periods and use it when the demand for electricity is high. Using energy storage systems help to stabilize the grid with the increasing penetration of variable renewable energy.
3. To reduce time of use (TOU) charges and other charges
Energy storage for renewable energy consumers can help to save more energy when the utility bill charges such as consumption, demand, and time of use (TOU) charges are well applied and understood. Energy storage systems can help to reduce demand charges by charging for instance batteries when the demand at the facility is low and discharging when the demand at the facility is peaking or high i.e. applying peak saving. Also, energy storage can reduce TOU charges by charging when the energy cost is low (e.g. in the middle of the night) and discharging when the energy cost is high (e.g. late afternoon). By reducing demand charges and TOUs, renewable energy consumers can reduce their utility bills significantly by charging and discharging when it is needed.
4. To reduce greenhouse gas emissions from fossil fuel sourced electricity
Energy storage can allow renewable energy consumers to displace more fossil fuel sourced electricity by storing any excess power generated during the day in the case of solar power and discharging during peak hours when it is highly needed. New energy storage systems can allow storage of electricity generated from wind and solar on shorter time frames to smooth variability, and on longer cycles to replace even more fossil fuels. For instance, new energy storage systems like flow batteries have relatively little degradation of their fluids or electrolyte solutions giving them longer charge-discharge cycles and longer life spans. They can also be scaled to match growing needs relatively by increasing the amount of fluid in the tanks. As such, reducing electricity sourced from fossil-fuels or reducing fossil fuel dependence will eventually help to reduce greenhouse gas emissions (GHGs).