Energy Storage:

Why is Energy Storage Important:?

Energy Density of Some Materials (KHW/kg)

Energy density storage drives the choices that can be made:

At the turn of the century electric vehicles were common place (using basically lead-acid batteries). Since gasoline has much higher energy density it quickly dominated the way vehicles were propelled.

In fact, gasoline has one of the highest energy density storage capacities known. This makes it very difficult to duplicate the convenience that gasoline has traditionally provided (e.g. 350 kg of batteries is equivalent to 1 kg of gasoline !).

Types of Energy Storage Systems

Pumped Hydroelectric Energy Storage:

Simple in Concept --> use excess energy to pump water uphill --> pump from lower reservoir (natural or artifical) to upper reservoir

Energy recovery depends on total volume of water and its height above the turbine

Cost Issues:

Suppose a company has a coal fired plant which operates at 36% efficiency and uses excess power to pump water uphill. The overall efficiency of recovering that to deliver to the consumer is 0.36 x 0.64 = 0.23 (23%)

Real Life Facility in Michigan

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