Renewable Energy Test

Question 1

Ethanol (Sugarcane) Pros:

Answer 1

Cost effective, homegrown, renewable, less greenhouse gas emissions, higher net energy than corn, less expensive than gasoline, production can be close to ethanol refineries.

Question 2

Tidal Energy Methods

Answer 2

Anaconda - water runs through a tube in the water and waves that run through it turn a turbine
Tidal Dams - hole in dam with turbine in the middle, water runs through it and spins turbine

Question 3

Tidal Energy Pros

Answer 3

We can predict tides, 80% efficiency, Low maintenance, 71% of earth is water

Question 4

Wind Energy Pros and Cons

Answer 4

Perpetual, 1 turbine = electricity for 500 homes, cheap and decreasing, moderate to high net energy yield, widely available, low electricity cost, no emissions, easy to build and expand

Question 5

Photovoltaic Panel

Answer 5

Cells that are connected electrically make up one panel; 29 states have adopted PV cells, target is SW states with most sunlight

Question 6

Solar Energy for High Temperature Heat and Electricity Methods

Answer 6

Parabolic Through Systems - U-shaped mirrors that reflect sun to heat oil
Power Tower - computer powered mirrors that follow sun and reflect onto main tower.
Dish Engines - big mirrors track sun to reflect and heat gas

Question 7

Solar Energy for High Temperature Heat and Electricity Pros and Cons

Answer 7

Pros: Clean power, jobs, could meet 25% of worlds electricity
Cons: moderate land/environmental impact

Question 8

Hydrogen Fuel Cells Pros and Cons

Answer 8

Pros: quicker refueling than battery, double the efficiency of normal cars, can be produced from plentiful water at some sites, no emissions, good substitute for oil
Cons: 1 ton of hydrogen = 11 tons of CO2, 96% of hydrogen in made from fossil fuels, negative net energy yield, high costs require subsidies, needs H2 storage and distribution systems;

Question 9

Geothermal Energy for Electricity

Answer 9

Dry geothermal: pump cold water into core and heat it into steam
Aquifer Extraction - taks hot water from aquifers and springs

Question 10

Geothermal Energy for Heating Pros and Cons

Answer 10

Pros: always available, 1/6 CO2 than other fossil fuels, moderate net energy and high efficiency at accessible sites, lost costs at favorable sites
Cons: Possible toxic solutions used to get heated, high costs and low efficiency except at concentrated and accessible sites, scarcity of suitable sites.

Question 11

Energy Conservation Methods (10)

Answer 11

Unused Plugs draw 10% of energy so use a power strip to be able to turn all of that off
Low emission windows, trees, dual-flush toilets, good insulation, geothermal heating, passive solar heating, energy efficient appliances and lighting.

Question 12

Hydroelectricity Methods, Location and Advantages/Disadvantages

Answer 12

Large scale dams - no pond needed = no flooding or relocation
Falling Water - uses natural heights to power electricity
Concentrated in 3 states - Cali, Oregon and Washington
Pros: 90% efficient, no waste and very reliable, large untapped potential, low-cost electricity
Cons: Large land disturbance and displacement of people, high methane emissions from rapid biomass decay, disrupts downstream ecosystems

Question 13

Waste to Energy Incinerator Pros and Cons

Answer 13

Pros: reduces trash, reliable source, creates jobs, reduces CO2 emissions from trash that would have been in landfill
Cons: costs $200 million to build, concentrated wastes, harmful waste

Question 14

Cogeneration

Answer 14

When two forms of energy are produced from the same fuel source. They can then both be used instead of one being wasted.

Question 15

What % of electricity is wasted by incandescent lightbulbs? What are the alternatives?

Answer 15

95%, LEDs or CFLs which last about 100 times longer than incandescent

Question 16

Photovoltaic Panel Pros and Cons

Answer 16

Pros: moderate net energy yield, no direct emissions of CO2, east to install and move around, competitive costs for newer cells
Cons: need access to sun, need electricity storage system for backup, prices high for older ones but decreasing rapidly, could disrupt ecosystems

Question 17

What is the world’s leading renewable energy source for electricity?

Answer 17

Hydropower

Question 18

Solid Biomass Pros and Cons

Answer 18

Pros: widely available in some areas, moderate costs, no net CO2 increase if harvested, burned and replanted sustainably, plantations can help restore degraded lands
Cons: moderate to high environmental impact, increases CO2 if harvested unsustainably, clear cutting can causes soil erosion, water pollution and loss of habitat, often burned in inefficient and polluting open fires.

Question 19

What percent of energy for cooking does biomass provide for the world and then for poor countries?

Answer 19

World: 10%
Poor: 95%

Question 20

What is biodiesel?

Answer 20

It is fuel produced from vegetable oils in plants like soybean, rapeseed and sunflowers.

Question 21

Pros and cons of biodiesel

Answer 21

Pros: reduced CO2 emissions, high net energy yield for oil palm crops, reduced hydrocarbon emissions, better mileage (up to 40%)
Cons: Increased NOx emissions and smog, low net energy yield for soybeans, compete with food for cropland, clearing natural areas for plantations reduces biodiversity

Question 22

What is ethanol?

Answer 22

Fuel made from plants like switchgrass, sugarcane and corn. Converts the plant starches into simple sugars which are processed into ethanol

Question 23

Why is switchgrass an efficient way to make ethanol?

Answer 23

It makes cellulosic ethanol, which is produced from inedible cellulose that makes up most of the biomass of plants. It uses the starch in the stalks and husks of plants to make ethanol. This eliminates any food wastes and a much higher net energy.

Question 24

Pros and Cons Ethanol

Answer 24

Pros: some reduction in CO2 emissions, high net energy yield, potentially renewable
Cons: low net energy yield with corn and higher cost, higher CO2 emissions with corn, corn ethanol competes with food crops and may raise food prices.

Question 25

What % of energy is wasted in the US?

Answer 25

84%

Question 26

What percent of energy use does industry account for?

Answer 26

30-33%

Question 27

What percent of energy does a coal-fired power plant waste?

Answer 27

66-80%

Question 28

What percent of energy in the US is from renewable energy sources?

Answer 28

7%