Flashcards
Energy storage
Cards in this deck (18)
- 1Problems solved by energy storage• Larger quantity of fuel can be accumulated
• Energy production rates can be kept constant for most of the economic use of equipment and workers
• Any surplus energy can be stored until required - 2Causes of fluctuations in energy supply:• Use of intermittent energy resources, e.g. solar
• Bulk delivery of transported energy resources - 3Causes of fluctuations in energy demand:• Short=term weather related fluctuations
• Seasonal fluctuations
• Weekday/ weekend fluctuations in industrial use
• 24 hr day/night fluctuations
• Short term behaviour related fluctuations - 4Reasons why there can be a surplus of electricity:• Base-load power stations generating 24 hrs a day even though much less electricity is needed ruing the night
• Fluctuations in demand
• If generated electricity is unused then its lost through heat from the cables - 5Development in energy storage technologies-Pumped shaving using pumped-storage HEP
-Compressed gas
-Chemical energy
-Rechargeable batteries - 6Pumped shaving using pumped-storage HEPSurplus electricity pumps water uphill which stores it as gravitational potential energy. Can then be converted to kinetic through water flowing to the lower reservoir, turning turbines and generating electricity. These can be much more responsive to changes in demand than stations powered by coal, gas or nuclear fuels.
- 7Compressed gasSurplus energy drives a pump that compresses air. Compressed air is released later to power machinery, and has been used on a small scale since 1870s. Current research focuses on large-scale schemes. Compressing air produces a lot of heat and this may also be stored, such as in molten salt thermal storage. It can recover 90% of the original energy.
- 8Chemical energyStored fossil fuels, biofuels, and hydrogen store chemical energy. Batteries and fuel cells can be used to store chemical energy. Rechargeable batteries enable the original chemicals to be reformed using electricity so that the batteries can be reused. However, for fuel cells to continue to operate new fuel and oxidant chemicals must be supplied.
- 9Rechargeable batteries: Factors affecting rechargeable battery viability• The efficiency of the storage cycle
• The number of charge-discharge cycles that can be carried out
• Energy density
• Cost per unit of energy stored
• Recharging speed
• Self-discharge during periods of non-use
• Safety issues: toxicity, fire risk - 10Types of energy storage-Vehicle to Grid systems (V2G):
-Power to gas systems (P2G
-Heat energy
-High volume storage
-Molten salt
-High thermal mass building materials
-Kinetic energy
-Electricity super-capacitors - 11Vehicle to Grid systems (V2G):systems where energy can be transferred between the grid and vehicle batteries. Batteries represent a big source of electricity if other sources can’t meet demand. Proposal that vehicles are plugged in when parking and so if demand is high a small amount of vehicle battery energy can be used. Avoids the cost and environmental impact of using power stations.
- 12Power to gas systems (P2G):use surplus electricity to produce gaseous fuel which can be stored. Water electrolysed, produces hydrogen. Used to produce methane than can be fed into the natural gas pipe network.
- 13Heat energyunavoidably lost from hit materials so long-term storage of heat is difficult. However short-term storage can be used which include the use of molten salt, high volume hot water stores and the use of high thermal mass materials. Material sued needs to have a high heat capacity.
- 14High volume storage:As the volume of a heat store increases, surface area: volume ratio goes down, so the rate of heat loss declines as there’s a smaller surface area for each unit of storage volume. Very large heat stores can be used for inter-season energy storage such as storing surplus energy from summer to heat buildings in winter.
- 15Molten salt:Potassium nitrate has a much higher boiling point than water, so it used at temperatures up to 550 degrees to store heat from photo thermal systems. Heat used later to boil water in a steam-turbine power station and generate electricity when needed. Hot water storage systems could only reach those temperatures if kept at high pressure which would increase costs.
- 16High thermal mass building materials:buildings constructed of materials with a high heat capacity warm up and cool down slowly. Reduces overheating in hot weather and the need for air conditioning. Recues need for heating at beginning of cold weather as the building materials keep the building warm for some time.
- 17Kinetic energy:flywheels can be used as a temporary store of kinetic energy. The rotating flywheel can be used to drive machinery or generate electricity when needed.
- 18Electricity super-capacitors:early capacitor deigns store electricity as electrical charge on flat plates conducting materials, separated by an insulator. The new super-capacitors use an electrochemical process and have a much higher energy density. In the future may be possible to use them for large-scale storage of electricity.
Information
- Description
- A level Environmental Studies Flashcards on Energy storage, created by Mollie Munday on 09/11/2018.
- Created by
- Mollie Munday
- Views
- 0
- Rating