Batteries

Deep-Cycle Battery

Source: http://s.sears.com/is/image/Sears/02827524000. Author: Sears. Permission: Fair Use.

Batteries store chemical energy that can be converted into electricity and have been identified as an essential component to making many renewable energies practical.  Batteries consist of electrochemical devices such as one or more galvanic cells, fuel cells or flow cells. During every interval in which power is used, a quantity of energy is released from the battery. That quantity of energy is equal to the amount of power, multiplied by the time the power flows.¹

The disposal and recycling process of batteries cause many environmental problems, such as toxic metal pollution.² In 1994 the member states of the Basel Convention on the Transboundary Movement of Hazardous Wastes included batteries on their list of hazardous wastes, limiting the often detrimental practice of exporting Lead Acid Batteries to developing countries for recycling. ³

Types of Batteries

There are two ways to classify different types of batteries: commercial application and construction method.

The major application types are marine, automobile and deep-cycle while the main construction types are flooded (wet), gelled or AGM (absorbed glass mat). The differences between the construction types are technical and not as relevant as the application uses of said batteries, covered below.

Automobile batteries (or “starter” batteries) are designed to provide large surges in voltage, namely for starting a car. Likewise, they are not designed for extensive discharge, which means that discharging a significant percentage of the electrochemical energy in a starter battery will significantly shorten the lifespan of said battery. Automotive batteries will generally fail after 30-150 deep cycles if deep cycled, while they may last for thousands of cycles in normal starting use (2-5% discharge).

Deep-cycle batters are designed for longer-duration discharge, meaning upwards of 80-90% of the batteries stored energy can be discharged without dampening the lifespan of the battery.⁴ These batteries do not provide large voltage, and are instead designed for sustained use (such as in electric vehicles). The internal difference between a deep-cycle battery and a starter battery is that in a deep-cycle battery the plates are thicker and solid, rather than the sponge-like plates used in starter batteries. This means less surface area (less instant voltage) but greater durability, allowing for deeper discharge. EV vehicle manufacturers, as well as electric forklifts, golf carts, motorcycles etc. use deep-cycle batteries as opposed to starter batteries, for obvious reasons.

Marine batteries are sometimes referred to as “hybrid” batteries because they can reach higher discharge rates than a starter battery, but are capable of providing larger surges of voltage than deep-cycle batteries can.⁵

Importance of Batteries for Renewable Energy

Electric Vehicle batteries

Source: http://cdn-www.greencar.com/images/b...-batteries.jpg. Author: greencar.com. Permission: Fair Use.

The improvement of battery technology is important to the future of renewable energy for several reasons.

In terms of Electric Vehicles, the primary obstacle to consumer demand for EV's is so-called "range anxiety", or fear of the limited-range of electric vehicles in comparison to liquid-fuel based vehicles. Improved batteries with greater storage capacity and more efficient and sustained discharge will directly address this issue, making future EV's more appealing to vehicle consumers. In the US, federal government incentives have increased in the field of advanced auto battery technology.  This, coupled with private market interest in marketing more hybrid and plug-in electric car has lead to some major improvements in battery technology and expansion of battery production industry. ⁶

Additionally, renewable energy power sources could be greatly expanded with improvements in battery technology. Several types of renewable energy are geographically limited, meaning they can only exist in certain areas (e.g. hydroelectricity on rivers, wind power in windy, flat areas) which are not necessarily proximate to large population centers. Due to severely outdated electrical grid technology, it is inefficient (and sometimes technically unfeasible or uneconomical) to transport this renewable energy to where it is needed, which prevents the expansion of renewable energy in many areas. Improved battery technology would allow for the mass storage of renewable energy, making its construction a viable commercial alternative in areas where before it was impractical. New designs in battery mass storage could be the solution to the on-off nature of wind turbines and solar panels. By storing energy when the wind stops blowing or the sun stops shining, it is hoped the new technology will boost to renewable energy and blunt a persistent criticism that the power from solar and wind is intermittent. ^{7 8}