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Exercise 3. Write a summary of part A of the text
Exercise 4. Write a review of part B in Russian.
Text 2
Renewable sources
Renewable energy is an alternative to fossil fuels and nuclear power, and was commonly called alternative energy in the 1970s and 1980s.
Biomass, biofuels, and vegetable oil
Biomass production involves using garbage or other renewable resources such as corn or other vegetation to generate electricity. When garbage decomposes, the methane produced is captured in pipes and later burned to produce electricity. Vegetation and wood can be burned directly to generate energy, like fossil fuels, or processed to form alcohols.
Vegetable oil is generated from sunlight, H2O, and CO2 by plants. It is safer to use and store than gasoline or diesel as it has a higher flash point. Straight vegetable oil works in diesel engines if it is heated first.
Pros
- Biomass production can be used to burn organic byproducts resulting from agriculture.
- Biomass is abundant on Earth and is renewable. Biomass is found throughout the world, a fact that should alleviate energy pressures in third world nations.
- When methods of biomass production other than direct combustion of plant mass are used, such as fermentation and pyrolysis, there is little effect on the environment. Alcohols and other fuels produced by these alternative methods are clean burning and are feasible replacements to fossil fuels.
- Since CO2 is first taken out of the atmosphere to make the vegetable oil and then put back after it is burned in the engine, there is no net increase in CO2.
- Vegetable oil has a higher flash point and therefore is safer than most fossil fuels.
- Transitioning to vegetable oil could be relatively easy as biodiesel works where diesel works, and straight vegetable oil takes relatively minor modifications.
- The world already produces more than 100 billion gallons a year for the food industry, so we have experience making it.
- Algaculture has the potential to produce far more vegetable oil per acre than current plants.
Cons
- Direct combustion of any carbon-based fuel leads to air pollution similar to that from fossil fuels.
- Some researchers claim that when biomass crops are the product of intensive farming, ethanol fuel production results in a net loss of energy after one accounts for the fuel costs of petroleum and natural-gas fertilizer production, farm equipment, and the distillation process.
- Direct competition with land use for food production and water use. As this decreases food supply, the price of food increases worldwide.
- Current production methods would require enormous amounts of land to replace all gasoline and diesel. With current technology, it is not feasible for biofuels to replace the demand for petroleum.
- Even with the most-optimistic current energy return on investment claims, in order to use 100% solar energy to grow corn and produce ethanol (fueling machinery with ethanol, distilling with heat from burning crop residues, using NO fossil fuels at all), the consumption of ethanol to replace only the current U.S. petroleum use would require three quarters of all the cultivated land on the face of the Earth.
Geothermal energy
Geothermal energy harnesses the heat energy present underneath the Earth. Two wells are drilled. One well injects water into the ground to provide water. The hot rocks heat the water to produce steam. The steam that shoots back up the other hole(s) is purified and is used to drive turbines, which power electric generators. When the water temperature is below the boiling point of water a binary system is used. A low boiling point liquid is used to drive a turbine and generator in a closed system similar to a refrigeration unit running in reverse.
Pros
- Geothermal energy is base load power.
- Economically feasible in high grade areas now.
- Low deployment costs.
- Geothermal power plants have a high capacity factor; they run continuously day and night with an uptime typically exceeding 95%.
- Once a geothermal power station is implemented, there is no cost for fuel, only for operations, maintenance and return on capital investment.
- Since geothermal power stations consume no fuel, there is no environmental impact associated with emissions or fuel handling.
- Geothermal is now feasible in areas where the Earth's crust is thicker. Using enhanced geothermal technology, it is possible to drill deeper and inject water to generate geothermal power.
- Geothermal energy does not produce air or water pollution if performed correctly.
Cons
- Geothermal power extracts small amounts of minerals, such as sulfur, that are removed prior to feeding the turbine and re-injecting the water back into the injection well.
- Geothermal power requires locations that have suitable subterranean temperatures within 5 km of surface.
- Some geothermal stations have created geological instability, even causing earthquakes strong enough to damage buildings.
Hydroelectric energy
In hydro energy, the gravitational descent of a river is compressed from a long run to a single location with a dam or a flume. This creates a location where concentrated pressure and flow can be used to turn turbines or water wheels, which drive a mechanical mill or an electric generator.
Pros
- Hydroelectric power stations can promptly increase to full capacity, unlike other types of power stations. This is because water can be accumulated above the dam and released to coincide with peak demand.
- Electricity can be generated constantly, so long as sufficient water is available.
- Hydroelectric power produces no primary waste or pollution.
- Hydropower is a renewable resource.
- The resulting lake can have additional benefits such as doubling as a reservoir for irrigation, and leisure activities such as water sports and fishing, for example Kielder Water in Northumberland, UK.
Cons
- The construction of a dam can have a serious environmental impact on the surrounding areas. The amount and the quality of water downstream can be affected, which affects plant life both aquatic, and land-based. Because a river valley is being flooded, the local habitat of many species is destroyed, while people living nearby may have to relocate their homes.
- Hydroelectricity can only be used in areas where there is a sufficient and continuing supply of water.
- Flooding submerges large forests (if they have not been harvested). The resulting anaerobic decomposition of the carboniferous materials releases methane, a greenhouse gas.
- Dams can contain huge amounts of water. As with every energy storage system, failure of containment can lead to catastrophic results, e.g. flooding
- Dams create large lakes that may have adverse effects on Earth tectonic system possibly causing intense earthquakes.
- Hydroelectric plants rarely can be erected near load centers, requiring long transmission lines.
Solar power
Solar power involves using solar cells to convert sunlight into electricity, using sunlight hitting solar thermal panels to convert sunlight to heat water or air, using sunlight hitting a parabolic mirror to heat water (producing steam), or using sunlight entering windows for passive solar heating of a building. It would be advantageous to place solar panels in the regions of highest solar radiation.
Pros
- Solar power imparts no fuel costs.
- Solar power is a renewable resource. As long as the Sun exists, its energy will reach Earth.
- Solar power generation releases no water or air pollution, because there is no combustion of fuels.
- In sunny countries, solar power can be used in remote locations, like a wind turbine. This way, isolated places can receive electricity, when there is no way to connect to the power lines from a plant.
- Solar energy can be used very efficiently for heating (solar ovens, solar water and home heaters) and daylighting.
- Coincidentally, solar energy is abundant in regions that have the largest number of people living off grid — in developing regions of Africa, Indian subcontinent and Latin America. Hence cheap solar, when available, opens the opportunity to enhance global electricity access considerably, and possibly in a relatively short time period.
- Passive solar building design and zero energy buildings are demonstrating significant energy bill reduction, and some are cost-effectively off the grid.
- Photovoltaic equipment cost has been steadily falling and the production capacity is rapidly rising.
- Distributed point-of-use photovoltaic systems eliminate expensive long-distance electric power transmission losses.
- Photovoltaics are much more efficient in their conversion of solar energy to usable energy than biofuel from plant materials.
Cons
- Solar electricity is currently more expensive than grid electricity.
- Solar heat and electricity are not available at night and may be unavailable because of weather conditions; therefore, a storage or complementary power system is required for off-the-grid applications.
- Solar cells produce DC which must be converted to AC (using a grid tie inverter) when used in currently existing distribution grids. This incurs an energy loss of 4–12%.
- The chemicals used to manufacture cells, and byproducts can be extremely hazardous.
- The energy payback time — the time necessary for producing the same amount of energy as needed for building the power device — for photovoltaic cells is about 1–5 years, depending primarily on location.
Tidal Power Generation
Tidal power can be extracted from Moon-gravity-powered tides by locating a water turbine in a tidal current, or by building impoundment pond dams that admit-or-release water through a turbine. The turbine can turn an electrical generator, or a gas compressor, that can then store energy until needed. Coastal tides are a source of clean, free, renewable, and sustainable energy.
Pros
- Tidal power is free once the dam is built. This is because tidal power harnesses the natural power of tides and does not consume fuel. In addition, the maintenance costs associated with running a tidal station are relatively inexpensive.
- Tides are very reliable because it is easy to predict when high and low tides will occur. The tide goes in and out twice a day usually at the predicted times. This makes tidal energy easy to maintain, and positive and negative spikes in energy can be managed.
- Tidal energy is renewable, because nothing is consumed in the rising of tides. Tidal power relies on the gravitational pull of the Moon and Sun, which pull the sea backwards and forwards, generating tides.
Cons
- Tidal power is not currently economically feasible, because the initial costs of building a dam are tremendous. Furthermore, it only provides power for around 10 hours each day, when the tide is moving in or out of the basin.
- The barrage construction can affect the transportation system in water. Boats may not be able to cross the barrage, and commercial ships, used for transport or fishery, need to find alternative routes or costly systems to go through the barrage.
- The erection of a barrage may affect the aquatic ecosystems surrounding it. The environment affected by the dam is very wide, altering areas numerous miles upstream and downstream. For example, many birds rely on low tides to unearth mud flats, which are used as feeding areas.
- Maximum energy production is limited to 2.5 terawatts. This is the total amount of tidal dissipation or the friction measured by the slowing of the lunar orbit.
Wind power
This type of energy harnesses the power of the wind to propel the blades of wind turbines. These turbines cause the rotation of magnets, which creates electricity. Wind towers are usually built together on wind farms.
Pros
- Wind power produces no water or air pollution that can contaminate the environment, because there are no chemical processes involved in wind power generation. Hence, there are no waste by-products, such as carbon dioxide.
- Power from the wind does not contribute to global warming because it does not generate greenhouse gases.
- Wind generation is a renewable source of energy, which means that we will never run out of it.
- Wind towers can be beneficial for people living permanently, or temporarily, in remote areas. It may be difficult to transport electricity through wires from a power plant to a far-away location and thus, wind towers can be set up at the remote setting.
- Farming and grazing can still take place on land occupied by wind turbines.
- Those utilizing wind power in a grid-tie configuration will have backup power in the event of a power outage.
Cons
- Wind is unpredictable; therefore, wind power is not predictably available. When the wind speed decreases less electricity is generated. This makes wind power unsuitable for base load generation.
- Wind farms may be challenged in communities that consider them an eyesore or obstruction.
- Wind farms, depending on the location and type of turbine, may negatively affect bird migration patterns, and may pose a danger to the birds themselves (primarily an issue with older/smaller turbines).
- Windfarms may interfere with radar creating a hole in radar coverage and so affect national security.
- Tall wind turbines have been proven to impact doppler radar towers and affect weather forecasting in a negative way. This can be prevented by not having the wind turbines in the radar's line of sight.
Words to know:
1. abundant
2. alleviate
3. flash point
4. residues
5. flooding
6. adverse effects
7. impart no fuel costs
8. photovoltaic
9. grid electricity
10. payback time
11. impoundment
12. harness
13. barrage
14. blade
15. contaminate
16. wind tower
17. grazing
18. power outage
Exercise 1. Explain the meaning of the following words and word combinations:
third world nations, feasible replacements, algaculture, binary, subterranean, dam, irrigation, aquatic and land-based plants, greenhouse gas, solar cells, living off grid, photovoltaics, payback time, gravitational pull, mud flats, remote areas, power outage, eyesore