Batteries are devices that store electrical energy in chemical form, and can either be used once and discarded (dry cell alkaline batteries) or rechargeable. Batteries are used for many applications including uninterruptable power supplies, cell phones, laptops, and for starting automotive engines. These applications typically require relatively small amounts of electrical power, either because the devices are small and not energy intensive (a cell phone) or because the power is used for a very short period of time (starting a car). The cost of energy in the form of AAA batteries is about $165 per kW-hr—more than a thousand times higher than the cost of the same electrical energy from a grid connected utility.
The amount of energy stored in typical batteries is much smaller than the amount of energy used in residential and commercial buildings, which means that many batteries need to be connected to provide appropriate capacity, a familiar problem for those brave souls attempting to live off grid. They have high maintenance cost and a limited lifetime – lead acid batteries will last perhaps five to six years in most remote power applications if properly pampered. This means that the cost of storage (the cost of the battery divided by the total number of kW-hours of storage possible) is often much higher than the cost of generating electricity directly from fuel, which means that batteries are generally not appropriate for long-term energy storage. One of the major advantages of fossil fuels is their ability to be transported and stored and used when needed - a property referred to as "dispachability".
A battery system is an uninterruptible power supply.
Batteries are currently used in Alaska village scale applications for providing short-term energy storage to allow a transition between a variable renewable energy source and a dispatchable generator. This is the case in the wind-diesel power system in Wales, and in many smaller applications, such as home or small community systems, where the cost of dispatchable generators can be quite high. Since batteries operate on direct current (DC), a power converter is also required to allow them to supply (and be charged by) alternating current (AC). There are many types of batteries with different operating characteristics. Several battery types can be considered for rural applications. The Alaska Energy Wiki discusses:
Other battery types
Several other battery technologies are in the R&D stage at a variety of companies. Increased market focus on high-quality, lightweight, inexpensive, and high-power density batteries for the electric and hybrid car markets will hopefully result in new battery types that hold promise for remote applications in the coming years.
