Chapter 10

Question 1

secondary battery

Answer 1

aka rechargeable battery

allows for chemical reaction in battery to be reserved by the application of a current into the battery, which recharges the chemistry and therefore the electrical energy available from it. rechargeable by reversing the chemical reaction, can be used over and over, through performance degrades over time till the battery is unusable.

Question 2

primary battery

Answer 2

aka primary cells. devices constructed of anodes, cathodes, electrolytes in such a way that they emit a charge. constructed to allow for the controlled chemical reaction of the components

Question 3

flow battery

Answer 3

still use chemical energy t store and deliver electricity though an electrochemical reaction, but store the electrolytes in separate storage outside of the device, and feeds them in as necessary to accept or deliver charge. Adding charge reduces the metal, and accepting charge oxidizes it. (Reduction + Oxidization = Redox).

diagram p. 354

Question 4

pumped hydro

Answer 4

gravitational potential energy.

pumped hydro storage is the method by which either fresh or salt-water can be pumped (using electricity) to a higher elevation, and store in some reservoir for later use. when energy is required, the water can be run, using gravity, through a turbine to generate electricity.

Question 5

compressed air energy storage

Answer 5

elastic potential energy

uses an electric powered compressor to force air into a closed container, which can be recaptured later by the release of that pressure driving an air-engine or pneumatic motor

can be used for vehicles, but is currently being used for grid-connected energy applications – utilize underground CAES (depleted nat. gas reservoirs)

Question 6

specific energy

Answer 6

the amount of energy that can be stored in the device or system per unit of mass

key when cost of device is heavily driven by cost of materials used in device

Question 7

energy density

Answer 7

compared to specific energy, is more about the ability to store energy PER UNIT OF VOLUME.

aka volumetric energy density
important when space constraints are binding on the application/technology choice

Question 8

specific power

Answer 8

in comparison with specific energy –

can be measured as function of POWER if the application is intended to provide primarily power outputs

Question 9

power density

Answer 9

in comparison with energy density –

can be measured as function of POWER if the application is intended to provide primarily power outputs

Question 10

round trip efficiency

Answer 10

efficiency with which energy can be stored and then converted back into electricity in the device/system.

High RT efficiency: a lot of the input energy that comes back is useful output (minimizes the losses in both physical and econ. sense)

Question 11

parasitic losses

Answer 11

batteries that are charged but not in use have a parasitic loss that reduces the amount of energy stored over time.

heat dissipation or electric discharge in chemistry batteries. evaporation/friction in physical storage methods

Question 12

response time

Answer 12

how quickly energy option can be called on either to accept or deliver electricity

Question 13

cycle life

Answer 13

total # of cycles that can be expected before the device degrades beyond an acceptable level of performance

vs lifetime – how long the asset will last
cycles = charge and discharge

Question 14

power quality

Answer 14

grid storage = load-shifting service (not energy generator)

storage allows grid operators to procure energy when cheap, and then delivers it as either power or energy (depending on timescale over which it is discharged) to end customer. these timescales correspond to the same services that grid operators are constantly procuring from various S&D sources and include

POWER QUALITY (instantaneous, such as in frequency regulation)

Question 15

peak shaving

Answer 15

very small amount of energy shifting

can have big impacts on the system’s power requirements and overall stability

Question 16

firming

Answer 16

intermittent generator firming: in jurisdictions where higher level of intermittent generator penetration is perceived to be a system stability risk, storage integrated within individual intermittent solar or wind installations or even aggregated portfolios of generators at a node may be required

also, firming Renewable Energy

Question 17

load shifting

Answer 17

allows for a energy input from a few hours earlier to be delivered at the peak

is compensated by the differential value for the electricity between when it is stored and when it is withdrawn

Question 18

load leveling

Answer 18

reducing the top of the load curve and filling in the bottom of the load curve

Question 19

day-night arbitrage

Answer 19

if energy value drivers only occur once per day, the ideal proposition would be to buy power at the cheapest part of the day (night) and sell it back during the peak hours of the next day (middle of day or late afternoon/early evening)

Question 20

levelized cost of storage

Answer 20

1. capital costs
2. O&M costs (typically only fixed O&M costs matter in managing a storage device, with variable O&M being subsumed into the cycle cost which is amortized in the capital costs above
3. Fuel costs - storage devices must have some input energy with some embedded cost associated with it.