Encyclopedia of Environmental Science and Engineering, Volume I and II

ENERGY SOURCES—ALTERNATIVES 309

with 15 to 30% of the original energy content of the coal with

the balance in the coke that is produced. Hydrogasification

processes can produce methane, a pipeline quality gas. The

waste products produced in a coal conversion include par-

ticulates, CO 2 and sulfur compounds but they are generally

easier to handle in this step which may also be carried out at

a site more remote from population centers than where the

fuel is consumed in an energy conversion operation.

Hydropower

Hydropower is the most important of the regeneratable

energy sources because of its highest efficiency at the energy

conversion. But its share on the total energy production lies

worldwide at only 3%. The possibilities of extension are lim-

ited and it is expected that in the year 2000 hydropower will

bring only 5% of the worldwide needed energy. That means

in absolute figures: throughout the world installed electri-

cal capacity of hydropower was in 1962 2.857 GW, while in

1978 it amounted to 3.960 GW. Some countries have almost

used their potential on available and usable hydropowers:

Switzerland near 100%

Germany about 75%

Austria about 60%

Europe more than 50%

USA about 22%

Brazil about 20%

There are two types of hydroelectric power plants:

1) Run-of-river power plants for the use of affluent

water;

2) Storage power plants (power stations with reservoir)

where the influx can be regulated with the help of a

reservoir.

Mostly greater differences in altitudes are being used,

like mountain creeks. Power stations with reservoirs are gen-

erally marked by barrages with earth fill dam or concrete

dams. A special kind of storage power stations is the pump

storage power station which makes it possible to use surplus

energy of the grid to pump the water to the reservoir and to

provide kinetic energy.

Though hydropower generally can be called environ-

mentally acceptable, there exist also some problems:

1) Change of ground water level and fill up of the

river bed with rubble.

2) Risk of dam breaks.

3) Great demand for land space for the reservoir (the

Kariba Dam in Central Africa produced a reservoir

surface of 1930 square miles and made necessary

the resettling of 50,000 people).

4) Diminution, but partly also increase of value of

recreation areas.

As the hydropowers of the world are limited, the world

energy demand however is rising, finally the share of hydro-

power will decrease.

Crude Oil

Hubbert estimates that the ultimate recovery, QF of crude

oil in the US, including Alaska, will be about 200 
 10 9 bbl.

TABLE 12

Estimated remaining coal reserves of the United States by rank and sulfur

content, 1965 (in billions of tons a )

Sulfur content % Anthracite Bituminous

Coal rank

Subbituminous Lignite Total

< 0.7 14 104 257 345 720

0.8–1.0 — 111 131 61 303

1.1–1.5 — 49 — 41 90

1.6–2.0 — 43 1 — 44

2.1–2.5 — 48 — — 48

2.6–3.0 — 52 — — 52

3.1–3.5 — 90 — — 90

3.6–4.0 — 128 — — 128

< 4.0 — 105 — — 105

Total 14 730 389 447 1580

a Coal in seams at least 14 in thick and less than 3000 ft deep in explored areas. Approximately

one-half of these reserves are considered recoverable.

Data source: Decarlo, J.A., E.T.T. Sheridan, and Z.E. Murphy, Sulfur Content of US Coals, Dept

of Interior. Bureau of Mines, Information Circular 8312, 1966, Washington, DC.

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