APES Renewable Energy Questions

Differentiate between passive solar heating systems and active solar heating systems.

A passive solar heating system absorbs and stores heat from the sun directly within a well-insulated structure without the need for pumps or fans to distribute the heat. An active solar heating system absorbs energy from the sun by pumping heat-absorbing fluid (such as water or an antifreeze solution) through special collectors usually mounted on a roof or on special racks to face the sun.

Explain the importance and potential of energy efficiency.

Energy efficiency is the measure of how much work we can get from each unit of energy we use. About 41% of the energy that we use is wasted unavoidably because of the degradation of energy quality imposed by the second law of thermodynamics. The other 43% is wasted unnecessarily, mostly due to the inefficiency of incandescent lights, furnaces, industrial motors, coal and nuclear power plants, most motor vehicles, and other devices. Reducing energy waste has numerous economic and environmental advantages. To most, reducing energy waste is the quickest, cleanest, and usually the cheapest, way to provide more energy, reduce pollution and environmental degradation, slow global warming, and increase economic and national security.

Describe two different ways to use geothermal energy.

Geothermal energy is heat stored in soil, underground rocks, and fluids in the earth's mantle. We can tap into this stored energy to heat and cool buildings and to produce electricity. A geothermal heat pump system can heat and cool a house by exploiting the temperature differences between the earth's surface and underground, almost anywhere in the world at a depth of 3-6 meters. In winter, a closed loop of buried pipes circulates a fluid, which extracts heat from the ground and arries it to a heat pump, which transfers the heat to a home's heat distribution system. We can also tap into deeper, more concentrated hydrothermal reservoirs of geothermal energy, ad Iceland has done for decades. Wells are drilled into these reservoirs to extract their dry steam, wet steam, or hot water, which are used to heat buildings, provide hot water, grow vegetables in greenhouses, raise fish in aquaculture ponds, and spin turbines to produce electricity. Cool water left over can be pumped back into the reservoirs to be reheated.

Briefly describe how a hydrogen fuel cell works and possible applications.

Hydrogen fuel cells combine hydrogen gas and oxygen gas to produce electricity and emit water vapor into the atmosphere. Widespread use of hydrogen as a fuel would eliminate most of the air pollution problems we face today. It would also greatly reduce the threats of global warming and climate change, because using it means no CO2 as long as the hydrogen is not produced with the use of fossil fuels of other carbon-containing compounds.

Why would you or would you not buy a plug-in with a lithium-ion battery?

I wouldn't buy a plug in car with a lithium-ion battery because current lithium-ion batteries have an occasional tendency to overheat, release oxygen, and in rare cases burst into flames so I would rather buy a car that uses established and researched energy sources.

Describe Iceland's resources, vision, and transformation towards a renewable energy economy.

Iceland gets almost three-fourths of its overall energy and almost all of its electricity from two renewable sources. One is geothermal energy from superheated groundwater and steam found close to its surface. This energy supplies electricity and provides heat for 80% of Iceland's houses and for producing vegetables in greenhouses. The other renewable energy source is hydroelectric power. Because it has no fossil fuel deposits, Iceland imports oil to run its cars, some of its factories, and the fleet of fishing boats that help to supply 60% of its income. By 2050-2060, Iceland has plans to eliminate its dependence on nonrenewable oil and to become the world's first country to run its economy entirely on renewable energy.

Explain the value of developing better batteries.

It is important to develop better batteries because we need a battery that can store enough energy to power a vehicle over long distances without overheating or even catching fire.

Describe the diferent ways of using biomass as an energy source, focusing on diesel and ethanol.

Liquid biofuels such as biodiesel and ethanol, which are produced from plants and plant wastes, can be used in place of petroleum-based diesel fuel and gasoline. The biggest producers of biofuels - Brazil, the United States, the European Union, and China- plan to double their production by 2020. Brazil already runs 45% of its cars on ethanol, and within a decade, could run all of its vehicles on this biofuel and eliminate its oil imports. U.S. government agencies estimate that biodiesel and ethanol could fuel 25-50% of U.S. motor vehicles by 2030.

Identity and describe 10 technologies that can be used to cut energy waste and increase efficiency in the areas of industry, transportation, and buildings.

One technology that can be used to cut energy waste and increase efficiency is cogeneration, or combined heat and power (CHP), systems. In theses systems, two useful forms of energy are produced from the same fuel source. For example, the steam produced in generating electricity in a CHP system can be used to heat the plant or other nearby buildings, rather than released into the environment and wasted. The energy of these systems is as high as 80%. Another way to save energy and money in industry is to replace energy-wasting electric motors, which consume one-fourth of the electricity produced in the United States. Each year, a heavily used electric motor consumes about ten times its purchase price in electricity-equivalent to using $200,000 worth of gasoline each year to fuel a $20,000 car. The energy savings from replacing all such motors would equal the output of 150 large coal-fired or nuclear power plants. Recycling materials such as steel and other metals is a third way for industry to save energy and money. Producing steel from a recycled scrap iron in an electric arc furnace uses 75% less energy than producing steel from virgin iron ore. Switching three-fourths of the world's energy-intensive cement producers used today's most energy-efficient dry kiln process, the global cement industry could cut its energy use by 42% and greatly reduce its CO2 emissions. A fourth way for industry to save energy is to switch from low-efficiency incandescent lighting to higher-efficiency fluorescent and LED lighting. A compact fluorescent bulb uses one-fourth as much electricity as an incandescent bulb, lasts ten times as long, and saves at least $30 in replacement costs during its lifetime. Converting the outdated U.S. electrical grid system into a more responsive and energy-efficient, digitally controlled network could save the nation $100 billion a year, according to the Electric Power Research Institute. A way that we can cut energy usage in transportation is by increasing our CAFE standards which makes it harder for companies to falsely claim their cars as "energy efficient". We can use green architecture, based on energy-efficient and money-saving designs, makes use of natural lighting, passive solar heating, geothermal heat pumps for heating and cooling, cogeneration, solar hot water heaters, solar cells, fuel cells, natural ventilation, recycled building materials, energy-efficient appliances and lighting, motion sensors for lighting, rainwater collection, recycled waste water, waterless urinals, composting toilets, and non toxic paints, glues, and building materials. Another important element of energy-efficiency design is superinsulation. A house can be so heavily insulated and airtight that heat from direct sunlight, appliances, and human bodies can warm it with little or no need for a backup heating system, even in extremely cold climates. The building cost for such a house is typically 5% more than that for a conventional house of the same size. However, the extra cost is paid back by energy savings within about 5 years, and the homeowner can save $50,000-$100,000 over a 40 year period. To save money in existing buildings we can insulate and plug leaks. About one-third of the heated air in typical U.S. homes and buildings escapes through holes, cracks, and closed single pane windows. The resulting energy loss is roughly equal to the energy in all the oil flowing through the Alaska pipeline every year. Lastly, we can heat houses more efficiently. In order, the most energy efficient devices we can use to heat space are superinsulation; a geothermal heat pump that transfers heat stored in the earth to a home; passive solar heating; a high-efficiency, conventional heat pump; small cogeneration microturbines; and a high efficiency (85-98%) natural gas furnace. The most wasteful and expensive way to heat a space is to use electric resistance heating with electricity produced by a coal-fired or nuclear power plant.

Describe the advantages and disadvantages of solar energy.

Some advantages are that energy is free, net energy is moderate, quick installation, no CO2 emissions, very low air and water pollution, very low land disturbance, moderate cost. Some disadvantages are that you need access to sun 60% of time, sun can be blocked by trees and other structures, environmental costs are not included in the marked price, need heat storage system, high cost, active system needs maintenance and repair, and active collectors are attractive.

Describe the advantages and disadvantages of producing electricity from water.

Some advantages of producing electricity from water are moderate to high net energy, high efficiency (80%), large uncapped potential, low-cost electricity, large life span, no CO2 emissions during operation in temperate areas, can provide flood control below dam, provides irrigation water, reservoir useful for fishing and recreation. Some disadvantages are high construction costs, high environmental impact from flooding land to form a reservoir, environmental costs not included in market price, high CO2 emissions from rapid biomass decay in shallow tropical reservoirs, danger of collapse, uproots people, decreases fish harvest below dam, and decreases flow of natural fertilizer to land below dam.

Explain the advantages and disadvantages of geothermal energy.

Some advantages of using diesel and ethanol for energy are reduced CO2 emissions, high net energy yield for oil palm crops, moderate net energy yield for rapeseed crops, reduced hydrocarbon emissions, better gas mileage, and potentially renewable. Some disadvantages of using diesel and ethanol for energy are increased NO2 emissions and more smog, higher cost than regular diesel, environmental costs not included in market price, low net energy yield for soybean crops, may compete with growing food on cropland and raise food prices, loss and degradation of biodiversity from crop plantations, and can make engines hard to start in cold weather.

Describe the advantages and disadvantages of using geothermal energy.

Some advantages of using geothermal energy are very high efficiency, moderate net energy at accessible sites, lower CO2 emissions than fossil fuels, low cost at favorable sites, low land use and disturbance, and moderate environmental impact. Some disadvantages are scarcity of suitable sites, can be depleted if used too rapidly, environmental costs not included in market price, CO2 emissions, moderate to high local air pollution, noise and odor, and high cost expect at the most concentrated and accessible sources.

Describe the advantages and disadvantages to using hydrogen as an energy source.

Some advantages of using hydrogen as an energy source are that it can be produced from plentiful water, low environmental impact, renewable if produced from renewable energy resources, no CO2 emissions if produced from water, good substitute for oil, competitive price if environmental and social costs are included in the cost comparisons, easier to store than electricity, safer than gasoline and natural gas, nontoxic, and high efficiency in fuel cells. Some disadvantages of using hydrogen as an energy source are that it is not found as H2 in nature, energy is needed to produce fuel, negative net energy, CO2 emissions if produced from carbon-containing compounds, environmental costs not included in market price, nonrenewable if generated by fossil fuels or nuclear power, high costs, will take 25 to 50 years to phase in, short driving range for current fuel-cell cars, no fuel distribution system in place, and excessive H2 leaks may deplete ozone in atmosphere.

Describe the advantages and disadvantages of producing electricity from wind.

Some advantages of wind power are moderate to high net energy yield, high efficiency, moderate capital cost, low electricity cost, very low environmental impact, no CO2 emissions, quick construction, easily expanded, can be located at sea, land below turbines can be used to grow crops or graze livestock. Some disadvantages of wind power are steady winds needed, backup systems needed when winds are low, plastic components produced from oil, environmental costs not included in market price, high land use for wind farm, visual pollution, noise when located near populated areas, and can kill birds and interfere with fights of migratory birds.

Using figure 16-33, compare the list of solutions of what you can do to be more sustainable in your energy use.

To be more sustainable in our energy use we can improve energy efficiency, create more renewable energy, and reduce pollution and health risk. To improve energy efficiency we can increase fuel-efficiency standards for vehicles, buildings, and appliances, mandate government purchases of efficient vehicles and other devices, provide large tax credits or feebates for buying efficient cars, houses, and appliances, offer large tax credits for investments in energy efficiency, reward utilities for reducing demand for electricity, and greatly increase energy efficiency research and development. To provide more renewable energy we can greatly increase use of renewable energy, provide large subsidies and tax credits for use of renewable energy, include environmental costs in prices for all energy resources, encourage government purchase of renewable energy devices, and greatly increase renewable energy research and development. To reduce pollution and health risk we can cut coal use by 50% by 2020, phase out coal subsidies, levy taxes on coal and oil use, and phase out nuclear power subsidies, tax breaks, and loan guarantees.

Identify ways electricity can be produced from the water cycle.

Water flowing from higher to lower elevations in rivers and streams can be controlled by dams and reservoirs and used to produce electricity. This form of energy is called hydropower. It is an indirect form of solar energy because it is based on the evaporation of water, which is deposited at higher elevations where it can flow to lower elevations in rivers as part of the earth's solar powered water cycle.

Identify and describe three interesting examples to represent the possibilities of using solar energy.

We can use solar energy to cool buildings naturally, produce high-temperature heat and electricity and cook food. Direct solar energy actually works against us when we want to keep a building cool, but we can use indirect solar energy and other natural services to help cool buildings. Solar thermal systems concentrate and transform energy from the sun into high-temperature thermal energy, which can then be used directly of to heat water and produce steam to generate electricity. On a smaller scale, inexpensive solar cookers can focus and concentrate sunlight to cook food, especially in rural, sunny areas.

Explain the important components of transitioning to a more sustainable energy future.

When transitioning to a more sustainable future it is important that the prices of selected energy resources are kept artificially low to encourage use of those resources. Next, the energy prices need to be kept artificially high for selected resources to discourage their use. Lastly, governments can emphasize consumer education.

Explain how wind is used to produce electricity.

Wind can be captured by wind turbines and converted into electrical energy.