Flashcards
Renewable energy resources
Cards in this deck (38)
- 1Application to current uses of energyMany modern technologies have been developed for fossil fuels. Renewable resources provide a large amount of energy but may be low temp or electricity which isn't as useful.
- 2Size of available resourceAvailable resource controlled by natural processes. Total resource maybe large but geographical constraints and energy density may limit amount that can be exploited.
- 3Level of technological developmentRenewable resources not fully developed so hard for the new technologies to compete against fossil fuels. Difficult for technology to be financially viable during early development.
- 4IntermittenceMany renewable resources need natural processes which don't always occur so they're not available all the time.
- 5Energy densityThis can be considered as energy output per quantity of fuel or equipment, depending on the resource used.
- 6Economic issues- New technology expensive
-Development costs have tobe paid before profit
-As demand rises, costs drop and product more affordable
-Most of the cost for renewables is cost of equipment which must be paid before any income - 7Solar - photothermal systemsHarness sunlight to produce heat, usually as hot water. Used for heating or washing.
Panel: black absorber, glass panel, insulation, absorber of good conductor and angled to maximise light absorption. - 8Solar - photovoltaic systemsHarness sunlight to produce electricity. Panel absorbs sunlight, displaces electrons, producing negative layers. Electrons flow to the rear layer; positively charged.
Used in parking meters, livestock electric fences. Ideal for remote parts of LEDCS.
Solar power in Spain, uses team to generate electricity. - 9Solar-passive solar architectureUsed for building design for heating and cooling. Include: large window facing sun, solar screens prevent overheating, solar heated convection ventilation. A conservatory can increase heating of the building where sunlight is absorbed, converted to heat.
- 10Solar-heat pumpsUses heat off the ground or air warmed by solar energy to produce more intense heat energy. Uses change of state, when liquid turns to gas absorbs heat energy , then gas to liquid heat given out. Use energy from warm soil and release it into building. Uses pressure to give out heat.
- 11Solar - concentrating solar powerParabolic reflectors used to increase energy density. Light absorbed by tubes of oil, heats molten salt. Salt can be used to boil water and drive stream turbines whenever electricity is required.
- 12Solar - photovoltaic/photothermal hybrid systemsEfficiency of PV cells drops at higher temperatures. Hybrid systems absorb heat and seit to heat space of water heating. Cools PV cell and increases its efficiency.
- 13Solar-transparent PV cells. Solar - HelliostatsPV cells that can come through incorporated into windows. Some are transparent whilst others can provide shading and reduce overheating.
A Heloistat alters the angle of a solar panel that it's always at the optimum angle for absorbing sunlight. - 14Solar - future develpmentsHi Multi-junction PV - use wider range of materials, absorb greater range of wavelengths so more electricity
Anti-reflective coatings - ordinary reflect about 30% of sunlight. Textured reflect more sunlight and increase electricity.
Energy storage - solar power is intermittent but can be stored in hot molten salt. Then used to boil water and generate electricity. - 15Biofuels - how they're usedMain biofuels: wood, charcoal, sugar, vegetable oils, straw and methane.Power stations modified and some purpose built. Vegetable oils and animals fats used as a diesel replacement. Anaerobic digestion of sewage can be used for agricultural fertiliser and as a biogas which can be used as a fuel.
- 16Biofuels - New developmentsHydrogen from algae - if algae are deprived of sulfur, hydrogen is produced and so aim to use bioengineered enzymes and catalysts such as platinum.
Anaerobic digestion - many raw materials are being used, crop and food waste.
Cultivation of marine algae - processed to make liquid fuel or anaerobically to make methane - 17Advantages of biofuels- Supply rate can be controlled
- Can be stored until needed
- Vegetable oils used to replace fuels
- Fuels themselves as carbon neutral
- Energy density of alcohol and biodiesel is nearly as high as fossil fuels - 18Disadvantages of biofuels-Supply is limited to amount of waste produced
-Large areas of farmland required, may compete with food production
-Energy density of straw, wood and Miscanthus low than fossil fuels
- Intensive farming techniques used for the production may release nearly as much CO2 as fossil fuels - 19Wind power- harnessing the energyKinetic energy of wind used to deflect blades o a turbine which turns a generator. Vertical axis turbine - VAWT. Horizontal axis turbine - HAWT. VAWT's don't need to face the wind, are quieter than HAWT's and can operate at lower wind speeds, however the stress during rotation can cause cracking. HAWT's more efficient, but need a stronger tower.
- 20Wind power - new developmentsFloating turbines- few countries have shallow waters needed to fix turbines to the seabed. Floating turbines allow offshore turbines to be located in deeper water.
Blade tip fins reduce turbulence and increase efficiency.
Helical VAWT blades - efficiency of VAWTs with straight blades is less than helical blades that rotate more smoothly - 21Wind power - new developments continuedNacelle brushes- reduce the amount of escaping air between the base and central hub. Reduces amount of kinetic energy absorbed.
Direct drive turbine - most turbines have an AC gearbox, which reduces efficiency and can often break down. These don't have a gear box so they're more reliable.
Wind - assisted ships - these have been designed that use wind power to reduce other energy needed. - 22Wind power - Location constraintsWind velocity - reliability and strength of wind are affected by altitude and topography of an area. Areas with high wind velocity are coastal areas, upland areas, flat areas and the sea.
Isolation - small scale use of wind power is useful for isolated communities. Large-scale wind farms situated near electricity grid. - 23Wind power - locational constraints contLand requirement - require a large area of land over which the Aerogenerators can be dispersed. Land between can sill be used for other purposes, e.g. agriculture.
Public opposition - some people object to wind farms s they're located away from scenic and urban areas. - 24Harnessing wave powerPoint absorber - floating structure which rises and falls, attached to a non-moving base which turns a generator.
Overtopping/terminator device - breaking waves force water into a reservoir and as the water flows back to sea it passes through a turbine producing electricity. Sea walls can be used to increase wave height.
Oscillating wave surge convertor - water moves both horizontally and vertically producing a cycle which this movement pushes a plate which moves pistons to pump fluid over a turbine to generate the electricity. - 25Harnessing wave powerSurface attenuator wave power - hinged floating device which causes sections to push and pull pistons as the waves pass, generating a force over the turbine and electricity.
Oscillating water column wave power - rise and fall of the waves forces atwr up and down in a submerged chamber and the air that is forced out flows over turbines, generating electricity. - 26Design problems of wave power- Equipment has to withstand storm and corrosion
- Can be difficult to anchor equipment off stormy costas in deep water
- May be expensive to transport electricity from isolated areas - 27Wave power- new developmentsNot been fully developed due to lack of research effort. Major obstacles; designing equipment to withstand harsh environment, anchoring equipment to seabed and storage of energy
- 28Locational factors of HEP- Large catchment area
- High total rainfall
-Low water turbidity
- Impermeable bedrock beneath the reservoir
- Low seismic activity
- Suitable topography
-No serous land0se conflicts
- close to consumers on he national grid - 29Harnessing geothermal power - low temperaturesGeothermal springs - groundwater heated by hot rocks may come to the surface in hot spring. Used for district heating.
Geothermal aquifers - hot groundwater pumped to the surface from underground aquifers to be used in district heating schemes. - 30Harnessing geothermal power - high temperaturesGeothermal steam systems - groundwater at very high temperatures brought to the surface using a borehole, producing high temp steam to generate electricity
Hot dry rock systems - hot rocks near the sufrcae but n groundwater, two boregoles used. Water is pumped dow one and tseam is recovered in the second. - 31HEP - low head turbinesWaterwheels - waterwheels are less efficient than turbines but don't suffer from blockages.
Kaplan turbines - axial, flow turbines with blades that rotate to allow variations in water flow. Can harness up to 90% of kinetic energy of the flowing water.
Helical turbines - turned by water flowing down the screw to generate electricity. High efficiency and can use high turbidity water without being damaged.
Micro-hydro schemes - small-scale used in rural communities. DIvert part of the flow of a river to drive a turbine but don't create a barrier across the whole river. - 32Geothermal power - new devlopmentsConventional geothermal power stations need high pressure steam, a temperatures of at 180 degrees. Newer geothermal power stations can use colder water which is used to heat another fluid which then boils, producing high pressure gas which turns turbines and generators to produce electricity and this allows the use of geothermal power in areas that were previously unsuitable.
- 33Tidal power - barragesA dam across a estuary or bay where the water flows through sluices to turn turbines and generate electricity. Can be generated four times in a day. The sluices are closed after high and low tide so the water levels and when they're opened again, the water flows much faster.
- 34Tidal power - new developmentsSome concerns of the environmental impacts have delayed new developments, however smaller-scale tidal lagoons are less contentious as the areas affected can be chosen more carefully.
- 35Tidal lagoonsSurround a selected part of an estuary or bay. If electricity is being generated but demand is low then water can be pumped into a lagoon producing a water level higher than sea level.
- 36In-stream turbinesFixed to the seabed and absorb kinetic energy of the natural tidal flow. Harness much less energy than a barrage or lagoon but the environmental impacts are low.
- 37Advantages of tidal power- tide times and ranges are predictable due to positioned of the sun and moon being predictable
-tidal barrage on a large estuary has a large energy out out compared to other renewable schemes - 38Disadvantages of tidal power-intermittent periods when electricity can't be generated
-few suitable sites for construction of a barrage, where it would be economically viable
- environmental impacts of barrages see large compared with the impacts of most other renewable resources
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- A level Environmental Studies Flashcards on Renewable energy resources, created by Mollie Munday on 12/09/2018.
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- Mollie Munday
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