Unit IV
New Words and Word Combinations
primordial power source первичный источник энергии
radioactive decay радиоактивный распад
to derive from извлекать, получать, выводить
molten а расплавленный
benefit n польза, выгода, прибыль
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heat tapping
emanate v
harmful emissions
spin v
production well
closed-loop circuit
technique n
heat exchanger n
energy-extraction
ground-source heat pump
groundwater n
heat sink
dwelling n
available a
reliance (on) n
electrical grid
toxic waste
to contribute
to
исходить, истекать, испускать
вредные выбросы (в атмосферу)
крутить, вертеть, запускать
эксплуатационная скважина
замкнутый контур
метод, способ,технология
теплообменник
отбор энергии
тепловой насос подземных источников
подземная вода
теплоотвод
жилище, дом
имеющийся в распоряжении
опора, надежда (на), доверие
электрическая энергосистема
токсичные (ядовитые) отходы
делать вклад, способствовать
1. Translate the following verbs and make up sentences with them.
Recreate, readjust, recondense, reuse, redouble, recollect, refine, reform, readdress, reappear, rearrange, recharge, reclassify, recycle, refund.
2. Read and translate text iva using a dictionary. Text iva. Geothermal Power
Energy from the Earth itself will play an important part in the renewable energy equation of the 21st century. Ever since the world's first geothermal-generated electricity was produced at Larderello, Italy, in 1904, humans have tapped this primordial power source. Geothermal energy is derived from the heat contained within the planet, heat being very intense in some places, it melts mantle rock to create molten magma. Experts believe that the ultimate source of geothermal energy is radioactive decay occurring deep within the Earth. Geothermal heat is a renewable energy source primarily produced when ground water descending from the Earth's surface meets molten magma rising toward it. Some of this geothermal water circulates back up through faults and
cracks and reaches the Earth's surface as hot springs or geysers, but most of it stays deep underground, trapped in cracks and porous rock. In most regions of the world, this heat reaches the surface in a very diffuse state; however, in some areas, including substantial portions of the western United States, geothermal reservoirs exist close to the surface and are easily tapped for power generation.
Today, Americans benefit in a much different way from this important natural resource. Tapping the heat emanating from beneath the Earth's crust can generate electricity without harmful fossil fuel emissions. In geothermal power plants, steam, heat, or hot water provides the physical force that spins turbine blades to generate electricity. Engineers have developed several methods for converting geothermal energy into electricity, primarily dry steam, hot water, and binary systems. "Dry steam" reservoirs produce steam but little water. The steam is piped to where it can spin turbine generators that produce electricity. Hot water reservoirs form where magma flowing relatively close to the surface directly heats groundwater. Naturally pressurized, hot water flows to the surface via the production well, where a separator flashes the water into steam and turns turbines. When geothermal-heated water is not hot enough to flash into steam, it can still produce electricity in a "binary" power plant. In a binary system, the geothermal water is passed through a heat exchanger, where its heat is transferred into a second liquid, which boils at a lower temperature than water. When heated, the binary liquid flashes to vapor that expands across the turbine blades. The vapor is then recondensed into a liquid and reused repeatedly. In this closed-loop cycle, there are no emissions released into the air.
Another commercial geothermal-energy-extraction technique utilizes heat pumps. Ground-source heat pumps use the Earth or groundwater as a heat source in winter and a heat sink in summer. Heat pumps move warmth from one place to another, with the heat transferring from the soil to the house in winter and from the dwelling into the ground in summer. Similar to the temperature range in a cave, the temperature within the ground maintains a constant average in contrast to the constantly changing air above. The geothermal heat pump is one of the most efficient and nonpolluting home cooling systems available. This method reduces reliance on the electrical grid, resulting in significant environmental benefits and reduced energy costs. It is estimated
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that
between 10,000 to 40,000 heat pump systems are installed every year.
Geothermal energy is a reliable, decentralized power source for some regions, but like all renewable energy sources, inexpensive oil supplies undermine its potential. Despite the fact that this energy source is clean and renewable and can reduce our dependence on imported fuels, the fact remains that fields of sufficient quality to produce electricity economically are relatively rare in the US. Environmental concerns also cloud the implementation of geothermal facilities. Many of the most highly active areas are located in protected wilderness zones that environmentalists want to preserve. And although no combustion occurs, some systems produce carbon dioxide and hydrogen sulfide emissions, require the cooling of as much as 100,000 gallons of water per megawatt per day, and must dispose of toxic waste and dissolved solids.
Geothermal energy alone won't solve the energy problem, but it does help reduce reliance on fossil fuels. In 1999, geothermal-generated electricity saved the US 60 million barrels of oil. Considering the health and environmental costs from burning that much oil, this natural hotbed of energy should not be overlooked. US geothermal electric power generation was approximately 2200 MW in 1999, or about the same as four large nuclear power plants but without the radioactive waste. Geothermal energy currently ranks third among renewables, following hy-droelectricity and biomass gasification, and ahead of rapidly expanding solar and wind power. The heat of the Earth contributes to our arsenal of clean and renewable energy sources, but it still can't come close to replacing our reliance on petroleum .