Energy Storage – the Key to Alternative Energies
Energy storage enables the electric generated though solar photovoltaic devices or wind turbines to be used when it’s dark, cloudy, or calm. As Nathan Lewis, Professor of Chemistry, Division of Chemistry and Chemical Engineering Lewis Group at California Institute of Technology, framed it, energy storage is integral in facilitating the development of alternative energy programs.
While hydrogen fuel cells offer future promise to our energy storage needs, battery technologies could provide some immediate results. As with all technologies there are tradeoffs.
There are several competing approaches to battery development. Among these approaches include the lead acid, nickel metal hydride, and lithium-ion cells.
Lead acid: batteries are the oldest approach and are typically found under the hood of your car or truck. Nickel metal hydride batteries have been around for more than 25 years and are used in hybrid electric vehicles such as the Toyota Prius. Lithium-ion cells have been on the market since 1991 and are used extensively in cellular phones, laptop computers, and digital cameras.
There are several issues in dealing with batteries such as environmental, economic, power, safety, and useful life. Lithium-ion cells possess many advantages, but incidences such as laptop computers erupting into flames, leaves many concerns for applicability in motor vehicles. Despite the setbacks, lithium-ion technology could provide solutions to the electric vehicle.
Why is this battery technology important? Solving the energy needs of the motor vehicle has profound implications in solving our energy needs. Nearly 70% of our oil consumption is direct towards transportation essentially motor vehicles. Without a dedicated strategy to address the transportation market and specifically the automobile, our progress towards energy independence is an illusion.
There are several issues with the nickel metal hydride batteries currently used in hybrid electric vehicles. Nickel metal hydride batteries are heavy, bulky, require large storage space in the vehicle, and don’t offer great acceleration. Lithium-ion offer power, size, and weight advantages over nickel metal hydride batteries, and numerous companies are working to improve performance and ameliorate the negative connotations associated with flaming laptops.
One of the basic concepts in dealing with batteries is the measure of battery energy versus battery power. The amount of battery energy refers to endurance, how long will the battery last and is often measured in ampere-hours or watt-hours per kilogram of battery weight. The amount of power refers to the energy draw and is akin to delivering acceleration in an electric vehicle.
The following figure illustrates the measurement of battery power and energy. Lithium-ion batteries are differentiated in their ability to bridge the power and energy tradeoff.
Figure 1 Battery Power vs Energy
For home renewable energy projects such as solar or wind energy deployment, it is often recommended that a deep-cycle battery be used. Deep cycle batteries are able to draw down 70%-80% of their full power, offering longer energy life than a typical lead acid battery. In addition, newer materials such as Gel batteries and absorbed glass mat (AGM) that are sealed, maintenance free, and can’t spill, and therefore, are less hazardous. For a tutorial on home use batteries visit
BatteryStuff.com
An interesting perspective on battery design is presented Energy vs. Power by Jim McDowall. For a primer on how batteries work visit presented Battery Power The premise is that there are tradeoffs between designing a battery for high power versus high energy.
Research conducted at Stanford University suggest the battery life of lithium-ion batteries could be extended through the use of Nano-technology. The bottom line: energy storage is paramount to sustaining the development of alternative energies and battery technologies play a critical role in energy storage and further expanding the role of alternative energies.