The way one city plans to make use of its wastes

A futuristic structure just completed here is described as "the first full-scale pyrolysis solid-waste disposal and resource-recovery system in the world. "

Using the latest technology, this plant is designed to handle 1000 tons of refuse daily, more than half the total collected by the city.

At the moment, it is being tested to work out the "bugs" in its unique design. When in full operation, now expected within six months, trash will roll in by truck at a rate of 50 tons per hour. After shredding, it will be baked at 1,800 degrees Fahrenheit. Gases from this "pyrolisis" will be mixed with air and burned to produce steam expected to meet half the heating, air-conditioning needs of many downtown buildings.

Mineral harvest. Solids remaining after pyrolysis will be culled for usable products. Around 70 tons of iron and steel will be extracted daily with huge magnets. Another 170 tons of "glassy aggregate" will be recovered, to be used primarily for road building.

Remaining will be about 80 tons of carbon char residue, which be buried in a landfill or possibly used as a solid conditioner.

(U.S. News World Report, Washington, D.C.)

Примечания

1. futuristic – футуристический

2. pyrolysis – пиролиз

3. shred – кромсать; резать/рвать на клочки

4. downtown – деловой район города

5. char – что-либо обуглившееся; обжигать, обугливать(ся).

3.3 Tidal energy – a source of power

The production of electricity is a highly effectiv industry. Even apporoximate

estimates show that electricity is so cost saving that the investment in expensive thermal and hudroelectric power station construction is quckly recouped.

The growing consumption of electric power and of power resources in general is happening worldwide. So those natural phenomena wich offer promise as power sources are being looked at more closely.

One of these is oceanic tides, since the change in the ocean water level can be up to 15–16 metres.

The tidal wave produced by the interaction of the forces of gravity in the earth-moon-sun system alters the ocean’s water level. The annual power and energy potential of tides is between two and three million million kWh, greater than the aggregate capacity of all the world’s electric stations. If this potential were converted by tidal electric stations (TES), it would greatly ease the strain on power source we have now and save millions of tons of the fast disappearing traditional fuel.

But the planning and construction of a TES has several formidable hurdles to overcome – how to cope with the intermitten, pulsing nature of tides? How can turbines be effectively used given the low pressure of the tide? It is hard to design and even harder to build a tidal electric station amidst the forbidding ocean elements on the bleak coastal sites.

There was found a way of getting around the periodic character of tidal energy by using a hydro-generating unit operative in high and low tides both as a turbine and a pump, which would enable the stations to generate electricity regardless of the tidal phase.

L.Bernshtein, D.Sc. (Technology), suggested and developed the float thechnology for hydroelectric power stations. His idea is that the tidal elecric station would be built on the coast and then hauled out by tug to the site where it will operate.

This would eliminate the need of a foundation (which is extremely expensive to build, since you have to temporarily isolate and remove the water from sections of the bottom) and of building dams and auxiliary buildings. The float technology for TES construction is also promising and cost-saving because the station does not have to be built in a isolated area and because most of the construction can be done on shore and not at the site.

The first TES were built at practically the same time in the USSR and France in the late 1960s.The Rance station in France used the design suggested by Bernshtein in his 1961 book, and was the first commercial tidal electric station operating on the sun time cycle. But it costs three times more than a conventional hydroelectric power station of the same capacity.

The principal hurdle to vault in building the Kislogubskaya TES (USSR)was to achieve a light but srong structural building design. This was done by using the thin wall elemets in the station’s skeleton, while its float stability ease ensured by ballast sand.

The electricity generated by the Kislogubskaya TES for the Kola powergrid is a drop in the bucket, but the station’s importance as a research facility for the future harnessing of tides in the White and Okhotsk Seas cannot be overestimated. Indeed, when high capacity TES are built, problems like control of corrosion and accumulation of algae and other matter on the submerged structures, the development and application of structural materials resistant to the abrasive influence of ice, etc., will have to be overcome many of the technical problems crucial for the construction of future tidal electric stations and for hydro- engineering in general are being studied here, in the tough conditions of the polar region.

The huge amounts of power generated by tidal electric stations will feed industrial development in the North and the Far East and help remake the conditions of life and even the nature of these forbidding areas of the country.

(V. SOLDATENKOV, Candidate of Science (Technology), Moscow News)

Примечания

1. alter – изменять

2. interaction – взаимодействие

3. amidst = amid – среди, посреди, между

4. ease – легко, свободно

5. hurdle – препятствие

6. vault – прыжок

7. alga, pl. Algae – морская водоросль

3.4 How to harness earth‘s heat

Experts are studying ways to tap geothermal energy – underground heat – to do the work of man.

What is geothermal energy?

It is energy extracted from the natural heat of the planet itself. At great depths, the earth is extremely hot. There are many places, though, where this heat is transferred to within a few thousand feet of the surface, forming geological “ hot spots”.

Where do these hot spots occur?

They are more numerous than once believed. Much of the land in the Western States is underlaid with relatively shallow geothermal sources. In some locations, such as Yellowstone National Park, they create geysers, or hot springs. Satellite observations have detected some hot spots, and scientists studying the chemical composition of well water have discovered others.

What is useful potential of geothermal energy?

Enormous. Some scientists estimate that geothermal energy could supply 10 per cent of the country’s energy needs. A geopressuregeothermal formation underlying the Gulf Coast from Mississippi to Texas is estimated to contain recoverable natural gas about equal to known conventional reserves. Usable deposits of hot water and stream in Oregon are estimated to equal the energy potential of the Alaskan oil fields.

How can this energy be put to work?

It depends upon the geological formation. In some areas, wells can be drilled to tap naturally generated dry steam, which can be used to drive turbine generators. Many deposits of natural hot water are adequate for heating homes or offices. There are also dry hot spots – actually subterranean domes of recently molten rock – that some scientists believe can be used to generate steam. The plan, still only a theory, is to drill two wells into a dome, pump water down into one well and recover steam or heated water from the other well. The geopressure-geothermal type of formation can produce energy in three forms – water pressure, heat or natural gas.

If the potential is so great, why isn’t geothermal energy being

used?

It is, in a limited way. The Geysers Power Plant near Santa Rosa, Calif., has been generating electricity from natural dry steam since 1960. There are geothermal power plants in at least six other countries.

Natural hot water heats hundreds of buildings in Oregon and is used in sauna baths, greenhouses and industrial processes in many places. Six cities in Iceland, including Reykjavik, the capital, have been heated by geothermal energy for years.

Is there any environmental issue?

Yes, but the problems are less complicated than those associated with fossil fuels. Still, they are knotty. Besides steam or hot water, geothermal wells may produce noxious gases, which must be handled carefully.

There is also factor of water disposal. A well designed to drive a 100-megawatt power plant, for example, could produce up to 400,000 barrels of water a day, often highly saline. Most experts believe, however, that the water could be disposed of by reinjection into the ground.

Is geothermal energy economically viable?

Cost is the main obstacle to geothermal development. Except for the use of dry steam, most geothermal sites would require a large research-and-development investment.

(U.S. News & World Report, Washington,D.C.)

Примечания

1. "hot spot" – «горячее пятно/место» (в геологии)

2. well –скважина

3. spring –источник, родник, ключ

4. dome –купол, свод

5. barrel –бочка; баррель (мера жидкости: англ.= 163,65 л, для нефти = 159 л; мера веса = около 89 кг)

Date: 2016-02-19; view: 518; Нарушение авторских прав