7. Electricity Storage Options Flashcards
Battery
Electrochemical device in which potential energy is stored in various types of chemical bonds
Grid Storage
Stationary electricity storage device installed primarily for the purpose of supporting the grid. Vast majority of grid storage today is pumped hydro, used to meet peak power, instead of larger energy applications. Chemical battery storage is also developing, but they need to bring down upfront capital cost and cost per megawatt hour
Pumped Hydro
Gravitational potential energy. Pumped Hydro Storage is the method by which fresh or salt-water is pumped (using electricity) to a higher elevation, and stored in some reservoir for later use. When the energy is required, the water is run through a turbine to generate electricity. Where geology allows, substantial amounts of storage can be created cheaply, and overall efficiency of process is high
Portable
Portable storage devices take energy from the locations where energy is more available to places where energy is less available, but where energy demand happens. example: laptop. portable storage devices solve the where and how certain problem. portable devices are primarily batteries as opposed to mechanical storage.
Fuel cell
Device that converts chemical energy from fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Fuel cells are different from batteries in that they require a continuous source of fuel and oxygen/air to sustain the chemical reaction whereas in a battery the chemicals present in the battery react with each other to generate an electromotive force. Fuel cells can produce electricity continuously for as long as these inputs are supplied. The fuel cell market is growing, and Pike Research has estimated that the stationary fuel cell market will reach 50 GW by 2020
Energy Density (volumetric energy density)
the amount of energy that can be stored in the storage per unit storage volume
Specific Energy (gravimetric energy density)
the amount of energy that can be stored in the storage per unit of storage mass
Power density
the amount of power that can be transferred in and out of the storage device per unit time
Response time
How quick the storage can be called on to accept or deliver electricity. Storage that responds ultrafast is called a spinning reserve. Response time is very short for frequency regulation applications
Lifetime
How long storage can be in service, with more frequent charging and discharging (a cycle) resulting in quicker degradation. Measured in cycle life, or how many cycles can be expected before storage degrades below acceptable performance level
Hazmat issues
Materials used in chemical storage include acids and toxic metals that pose environmental hazards under accidents or end of life disposal. Any uncontrolled discharge of electricity is also a hazard
Cycles
Energy storage tends to degrade with use, which here refers to the cycles of charge and discharge
Cycle cost
Net capital cost per cycle
LCOS
Levelized cost of storage, include capital costs, O&M cost and fuel cost. Aggregates asset performance characteristics and capital costs into a cost per unit to be used to analyze economics of electric storage applications
Time Shifting
Energy applications for storage involve moving chunks of energy from the time generated to another time when they are more valuable. This time shifting can be for hours or days, depending on the design of the system in the amount of energy available. can occur through 1) load shifting: energy input from a few hours before the peak is delivered at the peak, and compensated by differential value for electricity. 2) load leveling (day-night arbitrage): buy power at the least energy demand part of the day (often at night) at the non-peak price of that time, and sell it back at the peak hours of the next day at the peaking price
