Equipment and products that enable us to use renewable energy instead of fossil fuels and conventional electricity are highly beneficial. Examples include solar thermal systems, solar electric (photovoltaic) systems, and wind turbines. Other power generation equipment, such as fuel cells and some energy storage systems (like batteries) are included here because they help us accommodate varied energy sources so that we may eventually move beyond fossil-fuel dependence.
Ojai Energy Systems manufactures OES2, a lithium-ion, deep-cycle battery designed for on- or off-grid, residential and light commercial applications. Each battery has a capacity of 2.3 kWh, but designed systems can reach 250 kWh, in either 12, 24, or 48 volt systems. The battery is operable from –4°F to 100°F before it begins to lose capacity. The battery has a projected life of 20+ years, is RoHS compliant, and remote monitoring is available. The OES2 can reach 90% depth of discharge (DOD) without shortening its lifespan, according to the company. It comes with a 10 year or 2500 cycle warranty.
Deep cycle batteries are used to store energy generated by wind, photovoltaic, and microturbine power sources when connection to the utility grid is not possible or desired. Unlike a shallow-cycle car battery, they are designed to be discharged and charged repeatedly over a long service life. There are three common types of deep-cycle batteries: flooded lead acid, sealed AGM, and lithium ion.
Flooded lead acid batteries have a well-established track record and industry infrastructure such as recycling plants developed for them, but they commonly require the use of virgin lead, a toxic metal whose mining and use pose significant environmental problems. These batteries require water be added as part of regular maintenance and while charging they generate explosive hydrogen gas that requires ventilation. Flooded lead acid batteries typically last 8–15 years.
Sealed absorbed glass matt (AGM) batteries, are similar to flooded lead acid batteries, but are sealed at the top. AGM batteries do not last as long as flooded lead acid batteries, so they are only recommended in poorly ventilated areas, areas where the batteries may get knocked over, or projects where reduced maintenance is a plus.
Lithium ion batteries use lithium salts and organic solvents rather than lead and acid to generate the electric charge. Lithium ion batteries are lightweight and may last longer than their lead acid counterparts, but they require rare earth minerals and require computer systems and temperature monitoring to run them safely, making them significantly more expensive.
Since all deep-cycle batteries are heavy and resource-intensive, proper care and maintenance for a long service life are critical for reducing their environmental impacts.
Purchase and dispose of batteries locally: they are very heavy, making them resource-intensive to transport.
For UPS systems, consider flywheels in place of banks of batteries. Flywheels store kinetic energy for short-duration power-supply, instead of the energy stored in chemical form in batteries. They are lighter and use less space.
Ratings and Commentary