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35 Cards in this Set
- Front
- Back
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renewable energy |
provided by processes that replenish themselves or are continuously present as a feature of the solar system. - includes: biomass, solar, wind, geothermal, and tidal - generally have far less pollution and no CO2 emmissions - make up about 13% of worlds energy supply, 10% is biomass, 2.3% hydroelectric, 0.7% all other sources |
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biomass |
- all human energy came from this source prior to the industrial revolution - primarily used for energy in the developing nations - 4 types: fuel wood, waste, crop residues/animal waste, energy plantations |
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fuelwood |
- low energy and bulky compared to fossil fuels, mostly used locally - primarily used for cooking, some used for heating - open fire cooking is least efficient and most common, using stove decreases energy requirements by up to 50% and decreases wood smoke breathed by people |
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waste |
- industries like lumber mills, paper mills, and processing sugar from sugar cane produce biomass waste - industries usual burn on site to power operations - 60% of solid municipal waste is biomass that can be burned for energy, must be sorted by residents and businesses but can be costly |
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crop residue and animal waste |
- leftover straw and stalks can be used for heat and cooking. - dried animal dung can be burned or processed in anaerobic digesters to provide burnable gas - bulky and have a low low energy-to-weight ratio so it doesn't make sense to transport far distances - removing crop residues leads to increased erosion, decreases organic matter to feed new crops, and ethanol production from cellulose is not economical |
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energy plantation |
-crops grown for energy production - include forests, sugarcane, corn, sugar beets, grains, kelp, palm oil, and others - good crops have a high yield of dry material per unit of land, which reduces land requirements and need to produce more energy than what is put in - corn takes about the same amount of energy to produce ethanol as the energy derived from ethanol |
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direct combustion of biomass |
- most common way to produce heat or electricity - 1% of all electrical energy production |
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ethanol |
- produced by fermenting sugars - sugar or starch from crop is crushed and mixed with water and yeast - yeast breaks down sugar and coverts it to ethanol and carbon dioxide - distillation removes water and other impurities - used for automobile fuel |
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biodiesel |
produced by oils in variety of crops like soybeans, rapeseed, and palm oil and some animal fats - must be modified chemically before being used for auto fuel - 2% of all diesel fuel worldwide |
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anaerobic digestion |
- decomposes animal waste or green biomass without oxygen, producing biogas (methane and carbon dioxide) - usually small on farms and power home or operations - also used on sewage treatment plants and on landfills |
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pyrolysis |
- thermochemical process for converting solid biomass to fuel - biomass super heated or burned in low oxygen envionment to produce hyrdocarbon rich gas mixture, oil-like liquid, and carbon rich residue - usually done to make charcoal, has a higher energy density than wood - liquid can be refined just like "regular oil" - gasification optimizes gas production, a mixture of carbon monoxide, hydrogen, methane, carbon dioxide, and nitrogen. Used as heat source or to produce electricity |
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habitat and biodiversity loss due to biomass |
- destruction of forestland faster than regrowth - effects land in Asia and Africa - increases desertification - plantations destroy natural ecosytems |
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air pollution from biomass |
- burning wood produces pollution including carbon monoxide and hydrocarbons - open air fires increases indoor air pollution - if done sustainably, has no net increase of carbon dioxide levels and does not lead to climate change |
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effects of biomass and food production |
- ethical issues of converting cropland to produce energy - crop residues and animal waste used for energy, removes important nutrients for farmers |
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hydroelectric power |
- 16% of worlds electricity - most common type are dams - smaller plants can be built on small rivers and streams with steep gradients and constant water flow with no dams - best in mountainous regions and large river valleys - can be increased by over 30% with current technology |
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environmental concerns with hydroelectric |
- dams flood vast areas of land - alter watersheds - changes water quality (changes temperature, amount of particulate matter, and oxygen content) - alters fish migration patterns - blocks silt from moving downstream, deposits in the reservoir |
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solar energy |
- major problems is intermittent and diffuse nature - must have back up systems or storage systems during nighttime - 3 types 1. passive heating system 2. active heating system: 3. electricity generation: |
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passive solar system |
- light energy is transformed to heat energy when it is absorbed by a surface. - earliest use to dry food and clothes and to make salt from seawater - northern hemisphere south side of buildings get more sun and can be built accordingly with bigger windows and materials that absorb heat |
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direct gain |
designing floors and walls to absorb heat during the day and release it at night |
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sunspace |
- like a greenhouse, built on the south side of a building - ventilation allows heat to circulate in the home |
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trombe wall |
- very thick, south facing wall - painted black and made of material that absorbs lots of heat - releases heat at night |
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daylighting |
- use of natural sunlight to brighten interior buildings, reducing need for electrical lights - clerestory: row of windows near the peak of a roof, used in open floor plans, used on north sides of buidlings |
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active solar system |
- requires a solar collector, a pump, and a system of pipes to transfer heat from production area to site of use - usually used for water heaters, pools, and homes - require other energy sources to heat when the sun isn't shining - easiest to install in new buildings not old |
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solar electricity, conventional generation |
- produces energy by turning a turbine with steam - has 2 different designs 1. solar power tower: focuses suns energy with mirrors at a centralized tower to directly create steam, only done at smaller level (5-20 megawatts) 2. parabolic trough: heats oil in pipelines up to 390 Celsius, pumped to water than turns into steam. can be made for much larger production |
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photovoltaics |
- solid-state semiconductor that convert light directly into electricity - made with silicon and other traces of elements - groups of solar cells and called solar panels - produces DC (direct current) and must be converted to AC (alternating current) with an invertor |
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wind energy |
- some areas have more wind and are better suited for electrical power generation - areas best suited are often far from dense population center, as electricity is transfered energy is lost - wind is variable, doesn't always blow - less than 1% worldwide energy consumption |
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environmental impact of wind energy |
- moving blades produce noise and can kill birds and bats |
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geothermal energy |
- 2 different types 1. geologically active areas have hot magma approach surface heating rock, heat from rock heats water that generates steam to produce electricity or heat buildings 2. heat pumps used in non geologically active area, extracts heat from interior of earth and exports it to coils (like a fridge) but cools earth and heats up buildings, use system of closed loop of underground pipe, water antifreeze solution circulates in pipes to extract heat from rock |
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geothermal energy environmental issues |
- steam contains hydrogen sulfide gas (smells like rotting eggs), sulfides can be removed - minerals corrode pipe requiring more maintenance - minerals are toxic to fish, so can't discharge into local bodies of water |
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tidal power |
- 2 high tides and low tides each day - some areas experience higher tides due to local geographical features like bays and inlets. - requires at least 5 meter difference in tides to generate power - very minimal potential, only 40 sites capable of generating power |
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technology and tidal power |
- very similar to hydroelectric dams - build a dam or "barrage" across a tidal bay or estuary, cheapest to build on bays with narrow openings - have gates and turbines to let water flow past generating power, acts just like dams - new hydro turbine: use submerged turbine harness ocean currents |
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environmental impact of tidal power |
- very minimal - could change tidal flows significantly affecting aquatic or estuary ecosystems significantly - change migration patterns of some fish and marine species |
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energy conservation: |
- saves money for consumers by reducing the need for energy consumption and makes meeting future needs easier - less costly examples include: fluorescent light bulbs use less electric and produce far less heat, can reduce air conditioning costs - more expensive upgrades: automatic dimming devices/light shutoff devices, energy saving windows/doors, upgrading insulation, and replacing inefficient heating systems and appliances - easy to turn down heat in winter and turn up air in summer |
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government action to increase energy efficiency |
- fuel economy standards in vehicles - tax incentives for energy efficient home renovations - ban sale of most incandescent light bulbs - increase energy efficiency standards on appliances - invest in more efficient electricity distribution - improved high speed rail transportation |
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payback period |
the cost savings of energy efficient appliances or materials - amount of time it takes to make up for higher initial cost |
