APES Renewable Energy Quiz

Passive Solar

promotes cooling in hot weather and retaining heat in cold weather WITHOUT using mechanical equipment

Passive Solar Examples

Overhangs that block summer sun but allow winter sun, walls/floors that absorb heat and release it during the night, trees as landscaping

Active Solar

• Energy systems that REQUIRE mechanical power

• Electric pump circulate air, water, or other fluids from solar collector to a location where heat is stored, additional pumps move heat to location where energy is converted and heated

Benefits to solar heating

• energy is free

• moderate to high net energy

• no CO2 emission

• low land and water pollution

• low land disturbance

disadvantages to solar heating

• needs access to sun 60% of the time

• blockage of sun access

• need heat storage system

• high cost

• maintenance & repair

• visually unattractice

solar electricity and the environment

• low impact

• variety of metals, glass, plastics, etc are used in the manufacture and use of solar equipment

• production and accidental spills could release toxic materials

• potential effects on desert ecosystems

parabolic dishes and troughs

mirrors focus solar energy onto pipes with heat-absorbing fluid

mirrors constantly track the sun for efficiency

solar thermal electric generation

uses focus collectors that produce steam for large solar power plants and not domestic purposes

solar collectors

• trap sunlight or absorb solar radiation to generate solar energy

• serves as an alternate to heat water and air

photovolatic cell

energy harvesting technology that converts solar energy into thermal energy

flat plate collectors

converts sunlight directly into electricity (made from thin layers of semi-conductors with few or no moving parts)

fastest growing source of energy

evacuated tube collectors

• multiple tubes are filled with alcohol that converts to gas when heated

• use of alcohol for transfer of heat absorbed eliminates the weight and roof structural problems caused by flat collectors

photovoltaic trade offs

• can allow individual to be “off the grid”

• emerging as a major contributor to developing countries

biofuels and human history

• energy from biomass is the oldest fuel used by humans

• was a major fuel source in the US until the end of the 19th century

• 1 billion people in the world still use wood as primary source for heat and cooking

biomass energy burned directly

using the heat directly for cooking (using a wood burning stove to heat up a pot of water)

biomass energy burned indirectly

using the heat indirectly (using the heat to power a power plant)

ethanol

• comes primarily from corn and sugarcane

• roughly 10-15% of gasoline volume is ethanol

• Largest producers are US and Brazil

ethanol advantage

• carbon neutral (the carbon emissions produced are already apart of the active carbon cycle)

Ethanol disadvantage

increase in food prices (takes away food from the market, less food = higher prices, low energy return)

methane digester

• makes use of animal manure

• manure left on ground can contaminate local water sources as it dissolves in the rain

• mature instead is collected and is allowed to undergo anaerobic decomposition to produce methane and carbon dioxide

• methane can be piped directly to the building for use is heating and cooling

advantages of bio-gases

burns cleaner than most other fuels because there are fewer impurities

saves money

reduces deforestation

can be used as fertilizer

disadvantages of bio -gases

some air pollution from burning methane

high cost of installing the methane digester

anerobic digester

device that promotes the decomposition of manure of organics in the manure to simple organics and gaseous biogas products

bio-diesel

oil made from recycled cooking oil, soybean oil, and animal fats

bio-diesel advantages

• lower CO2 emissions (carbon neutral)

• biodegrades as fast as sugar (degrades in a matter of weeks)

biomass advantages

• large potential supply

• makes use of wastes

• CO2 neutral

• algal biofuels utilize otherwise currently unrealized energy source

biomass disadvantages

• moderate to high environmental impact, producing more CO2 than other alt sources

• soil erosion & water pollution

• removing fertilizer from soil

• decrease in food production

wind power

wind produced when differential heating of Earth’s surface create air masses with differing heat contents and densities

which is the cheapest form of alt. energy?

wind

alternative to grasslands

• wind velocity often increases over hill tops or funneled through a mountain pass

• wind velocity is higher offshore

wind power and the environment

• kills birds

• uses large area of land

• wind speed is variable

• may degrades area’s scenic resources

• made of materials that are not recyclable

wind power advantages

no air pollutants or carbon emissions associated with wind farms, land can be used for alternative uses

future of wind power

• growing at approximately 20-40% per year

• 10 times the growth rate of oil use

• created thousands of jobs and investment opps.

• technology producing more efficient wind turbines

hydropower

supplies 20% of the world’s electricity

99% of electricity in Norway

electricity can be produced from tides and waves

large scale hydropower

• high dam is built across a large river to create a reservoir

• some stories water is allowed to flow through huge pipes at controlled rates spinning turbines and producing electricity

small scale hydropower

• low dam with no reservoir, built across a small stream

• streams flow of water is used to spin turbines and produce electricity

hydroelectric dams advantages

• water power is clean and efficient

• no burning of fuel or radioactive wastes

hydroelectric dams disadvantages

• flood large tracts of land

• block fish migration

• trap sediment that would replenish beaches

• evaporative loss of water from reservoirs

pumped storage hydropower

pumps use surplus electricity from a conventional power plant to pump water from a lake or reservoir to another reservoir at higher elevation

when more electricity is needed, water in the upper reservoir is released, flows through turbines, and generates electricity on its return to the lower reservoirs

tidal stream hydropower

tidal current flow provides the kinetic energy to turn a turbine on a fixed tower or bouy in regions where tidal flow is moderate to extreme

electricity is carried via buried wires to power stations onshore

tidal barrage hydropower

• a small dam is constructed across a tidal inlet, creating a tidal reservoir

• as the tide goes in and out, water passes through a one-way underwater tunnel system, spinning turbines in the process

• does not work during high and low tide times

wave hydropower

• form of wind power utilization, ocean and freshwater wave energy generated by prevailing and storm winds

• waves bend and flex the pleamis generators to generate electricity which can be connected by wires and carried to power stations

Ocean Thermal Energy Conversion (OTEC)

Energy from the sun heats the surface.

OTEC systems relies on the large difference in ocean temperatures to power a turbine to produce electricity

Warm water from the surface is pumped through an evaporator containing a fluid that vaporizes

The vaporized fluid drives the turbine, which powers a generator

The fluid is condensed using cold water pumped from the deep ocean

ocean energy

high energy in motion of waves, currents and tides in the ocean

• difficult to harness

• most successful = tidal power

• very few areas w/ right topography

North Umpqua River Winchester

• dam fish ladder contains right angle turns that create dead ends for fish trying to pass over dams. Fish get stuck in holes that have eroded in outdated gravel fill and metal injures fish

• botched repairs discharged sediment and wet concrete into river caused turbidity levels to spike 50% over background levels, causing contamination of primary drinking water source and loss of salmon

Xingu River dams in Amazon Rainforest

• reshaping of major tributary produced new dry areas affecting aquatic life and indigenous tribes living in area

• amount of forested and agricultural land declined due to flooding

• upstream species richness declines

• 85 % of the water is diverted -decrease in water levels leaves fish stranded from important habitats like floodplains, plants dependent on seasonal flooding have a disruption in reproduction cycle, animals depending on floods to carry them to food that provides energy to be able to reproduce

Three Gorges Dam

• landslides caused by increased pressure on surrounding land

• sits on two major faults (changing water level strains them, causing fault activity to increase and induce earthquakes)

hydropower advantage

• mod to high net energy

• large untapped potential

• No CO2 Emission

• reservoirs useful for recreation

hydropower disadvantage

• high construction cost

• high env. impact

• less silt downstream

• interrupts fish patterns

• danger of collapse

• decreased downstream flow

geothermal energy

heat stored in soil, rocks, and fluids in Earth’s mantle

geothermal energy environmental problems

• thermal pollution from wastewaters

• water may be saline or corrosive

• on-site noise

• emissions of H2S gas

• disturbance of land

why is H2 hard to use as an energy source?

• hydrogen is chemically locked up in water and other compounds

• it takes energy and money to produce hydrogen from water

• fuel cells best use hydrogen, but too expensive to mass produce

hydrogen fuel

• electric currents separates water into hydrogen and oxygen

• when H recombines with O, electrons flow between positive and negative poles

• H can be transported in pipeline

• Combustion product is water