Chapter 23 Biology
Solar technologies that capture heat without any electronic or mechanical assistance are called: A. passive solar technologies. B. active solar technologies. C. solar thermal systems. D. photovoltaic solar cells.
A
Which of the suggestions for saving energy could be done by a student living in a dormitory or rental apartment?
If you do not own your home you may be restricted to some of the no-cost ways to save energy. You could also encourage your school or landlord to invest in some of the steps that have a quick payback time.
key concepts
Renewable energy sources may be more expensive to use but only if the true costs of using fossil fuels are ignored.
key concepts
Samsø became energy positive by using a variety of renewable technologies that fit its locale and reducing overall energy needs through conservation.
key concepts
Water power can be harnessed to generate electricity. Large dams are the most common and productive method, but there are other, less destructive technologies in use and development.
True or False: While geothermal power plants need to be built near sources of underground heat such as hot springs, geothermal heat pumps can be installed in any homes built on land.
TRUE
passive solar technologies
Technologies that allow for the capture of solar energy (heat or light) without any electronic or mechanical assistance.
geothermal heat pumps
A system that transfers the steady 55°F (12.5°C) underground temperature to a building to help heat or cool it.
photovoltaic (PV) cells
A technology that converts solar energy directly into electricity.
solar thermal systems
An active technology that captures solar energy for heating.
Consider the area where you live. What mix of renewable energy sources would work best for your community?
Answers will vary but should be supported.
Do you feel the energy production and recreational/flood control benefits of large hydroelectric dams outweigh the permanent ecological and community destruction they cause? Explain your position.
Answers will vary but should be supported.
Some people feel that windmills and wind farms are eyesores, but one must also consider the alternatives. Would you rather live near a wind farm or a mountaintop removal coal mine? Explain.
Answers will vary but this question helps put the disadvantages of living near a windmill or wind farm in perspective. Perhaps windmills are an eyesore but the alternative could be much worse. Even if we don't live near a coal mining site, if we continue to use coal, then someone lives near one. This means our use of electricity harms those people and communities. Perhaps having wind farms in our own community is more just than coal mining sites in the communities of others.
12. Which of the following should you do first if you want to lower your electric bill? A. Install PV panels on your rooftop B. Have an energy audit done to see where your home is most inefficient C. Replace your appliances with energy-efficient models D. Install more insulation in your attic and exterior walls
B
Which disadvantage of large dams can the smaller run-of-the-river dams avoid? A. The smaller dams do a better job at flood control. B. The environmental damage of creating a reservoir is avoided. C. The smaller dams don't generate air pollution like the large dams do. D. Production capacity will be steady not variable, as with large dams.
B
To address climate change and other pollution issues associated with fossil fuels, we should begin to phase out fossil fuels and increase our use of renewables. Are we on track? Summarize the change in total energy use and the usage of renewables and fossil fuels from 2010 to the projected values for 2040.
Between 2010 and 2040 energy usage is predicted to more than double with increases in each sector except liquid fuels such that in 2040 we will have increased fossil fuel use, not decreased it.
Explain the importance of energy conservation in the overall plan to make Soms0 energy neutral (or even energy positive).
By conserving energy through energy efficiency and making conservation choices that use less energy, the people of Samsø require less energy per person than they might otherwise need. This allows the renewable energy sources they have to meet all their needs. Without this conservation, more energy production would be needed and the renewables on hand might not be able to produce enough for higher levels of consumption.
As a member of the city council in a small town in New Mexico, you must vote on a new source of energy for your growing community. What should be the first step in determining where the energy will come from? A. Rely on historical practices and build a new coal-fired power plant. B. Pass a new law that requires all buildings to have solar panels installed. C. Conduct an assessment of available energy sources, both renewable and nonrenewable. D. Provide citizens a tax subsidy for improving the energy efficiency of their homes.
C
Which of the following in not a characteristic of sustainable energy sources? A. They must be renewable. B. We must use them at or less than the rate at which they are replenished. C. They must have no environmental impact. D. All of these are characteristics of sustainable energy.
C
Which of the following is not an advantage that solar and wind power share? A. Pollution free B. Effective at large and small scales C. The most inexpensive renewable technologies to install D. Job creation
C
Energy advisors say "the greenest kilowatt is the one: A. produced by solar power." B. that doesn't harm the Earth." C. that's cheapest." D. you never use."
D
Which of the following renewable energy sources contributes the largest proportion of energy worldwide? A. Wind B. Water C. Solar D. Biomass
D
conservation
Efforts that reduce waste and increase efficient use of resources.
Describe the characteristics of the four sustainable energy sources presented here for generating electricity: wind, solar, geothermal, and hydroelectric power. Why are all sources not practical for every location?
Electricity produced from wind, geothermal, and water all share the common feature of some force turning a turbine which spins adjacent to copper wiring within a generator to generate electricity. Wind energy uses the power of wind to turn turbines (windmills). Geothermal energy uses the heat produced by the Earth to heat water and produce steam which turns a turbine. Water energy uses the energy of water falling downhill and/or running by to turn a turbine. Solar energy is different in that it uses the energy of the sun to displace electrons in a photovoltaic cell which generates electrical current. All sources are not practical for every location because all locations don't have abundant sunlight, or water, wind, etc. The practicality of these depends on abundance, and abundance varies across the planet.
wind energy
Energy contained in the motion of air across Earth's surface.
biomass energy
Energy from biological material such as plants (wood, charcoal, crops) and animal waste.
sustainable energy
Energy from sources that are renewable and have a low environmental impact.
Renewable energy
Energy from sources that are replenished over short time scales or that are perpetually available.
solar energy
Energy harnessed from the Sun in the form of heat or light.
hydropower
Energy produced from moving water.
True or False: The use of fossil fuels is projected to decline in the next 50 years as the use of renewable energy sources increases.
FALSE
Explain how a geothermal heat pump works and how it can lower both heating and cooling costs for homeowners.
Fluid filled pipes are buried underground and this fluid is pumped through the pipes from the ground to the house and back again. The fluid picks up the 55°F temperature of the ground and delivers this to the home. In the summer this can be used to cool the home (reducing air conditioning bills). In the winter the home only needs to be heated from a starting place of 55°F — requiring that a furnace work much less than if it were heating the house up from the outside temperature, thus lowering heating bills.
key concept
Fossil fuels are the leading fuel for electricity production. The use of both renewables and fossil fuels is rising, due to increased energy demand.
key concepts
Geothermal energy can be captured on a small scale to lower home heating and cooling costs or on a large scale to produce electricity or heat.
Compare and contrast the production of electricity by a wind turbine and the production of electricity by heating water to produce steam (thermoelectric production).
In both cases the ultimate goal is to turn a turbine attached to a generator to produce electricity. With a wind turbine, the wind mechanically rotates the generator. With thermoelectric methods, steam turns the turbine to rotate the generator. The main difference is the production of waste products (emissions from burning a fuel or nuclear waste) from thermoelectric production. Another difference is scale and ease of increasing output on demand - a single coal or nuclear power plant can produce as much electricity as hundreds of wind turbines and their output is more easily increased or decreased to meet demand.
Core message
In order to become a sustainable society, we need to transition to reliable, renewable energy sources with acceptable environmental and social impacts. No single energy source can replace fossil fuels. Instead, a variety of methods, selected to meet the needs of the population, and availability of local energy sources, will help communities shift to sustainable energy use. Fortunately, we have many good options already at our disposal, with other new methods currently in research and development.
In terms of reducing fossil fuel use, why should you make your home as energy efficient as possible before installing active solar technologies?
It makes sense to reduce your energy use by reducing energy waste before installing PV panels or a solar hot water heater. The cost of insulation and energy efficient appliances are less expensive than the solar technologies; for the same cost they may save more energy than the solar technologies produce. Then, with a home that requires less energy, a smaller (more affordable) solar array would be able to meet your energy needs.
active solar technologies
Mechanical equipment for capturing, converting, and sometimes concentrating solar energy into a more usable form.
key concepts
Meeting our energy needs with renewable sources becomes more likely when we pair renewables with energy conservation measures.
Though the price is decreasing, LED bulbs are much more expensive than CFLs. In 2013 there was no real cost difference to buy and burn one LED bulb compared to five CFL bulbs. Why is it still enviromentally advantageous to use LEDs bulbs rather then CFLs if your electricity comes from a coal power plant?
Over the course of its life, the LED bulb will use less electricity and thus generate less air pollution.
What is the concept of "payback time," and how can it be useful in deciding what types of conservation measures to pursue?
Payback time is the time it takes for the energy savings of an energy upgrade to pay for the cost of its purchase and installation. Knowing the payback time of different options allows homeowners to choose the most cost-effective upgrades.
geothermal power plants
Power plants that use the heat of hydrothermal reservoirs to produce steam and turn turbines to generate electricity.
key concept
Solar power can be harnessed in many ways. It is pollution free but is expensive and is less productive at higher latitudes, on cloudy days, and at night.
key concept
Sustainable energy sources are those that meet our needs, have acceptable impacts, and are readily replenished.
How were Native Americans and wild salmon populations adversely affected by the construction of the Grand Coulee Dam? Do you think this dam should have been built? Justify your answer.
The Native Americans lost their homes and ancestral lands — villages, burial grounds and other sacred places were permanently flooded and inaccessible. The salmon were unable to access their spawning streams. Whether the construction of this dam was worth the price depends on how much weight one gives the benefits (electricity to the region; reduced need to burn fossil fuels) and the disadvantages described above.
payback time
The amount of time it would take to save enough money in operation costs to pay for the equipment.
The two geothermal technologies are quite different. Which one actually prouduces electricity, and which one helps you conserve energy?
The geothermal power plant uses the heat from the Earth in a thermoelectric power plant to produce electricity. The ground-source heat pump raises the temperature of your home in the winter so that you are only heating your home up from a starting place of 55°F, rather than the outside temperature. In the summer, the cooler temperatures found underground are delivered to the home to cool it.
geothermal energy
The heat stored underground, contained in either rocks or fluids.
key concept
Wind power is pollution free but is an intermittent energy source. In addition, turbines are dangerous to wildlife, and some consider them eyesores.
Samsø used_____________,_______________, and __________energy sources to meet its energy needs.
Wind, solar, and biomass