Jökull - 01.12.1961, Blaðsíða 59

(3) ECONOMY OF PRODUCTION AND
LONG-DISTANCE PIPING
(a) Production cost.
The cost of production of geothermal energy
includes drilling, casing, well-completion and
the piping of the geothermal fluid to a point of
collection within the thermal area. Data in the
case of three important thermal areas in Ice-
land are given by Bodvarsson and Zoéga (G/37).
These areas are (1) the Reykjavik area witliin
the city of Reykjavik, (2) the Reykir area some
16 km north-east of the city and (3) the Hengill
area some 45 km east of the city. The main
data are as given in the following TABLE I.
of the problems involved in the piping of geo-
thermal fluids.
The geothermal fluids, hot-water and natural-
steam, are relatively poor carries of heat. Their
transportability is one or two orders of magni-
tude less than that of natural gas, and depends,
as a matter of course, critically on the type ancl
size of market for the heat.
(i) The Reykir-Reykjavik pipeluie. As of
now there is in operation only one major
pipeline transporting geothermal energy for
heating purposes. This is the 15.3 krn long line
connecting the thermal area at Reykir to the
city of Reykjavik. Some details of design of
the line are given by Sigurdsson (G/45) and
TABLE I
Production cost in three thermal areas in Iceland.
(Gcal = Gigacalorie = 109).
(1) Temperature of production
(a) range ................................
(b) average ..............................
(2) Free flow ................................
(3) Production depth .........................
(4) Production cost of heat for space heating .
(5) Production cost based on latent heat of na-
tural steam at 3 atm abs..................
The cost data given in the table include capi-
tal cost, maintenance, wages and power.
Taxes and profits are excluded. Item (4) is
computed on the basis of space heating as the
market for the heat. Tlie data is the cost per
unit sensible heat above 40° C contained in the
geothermal fluid. This lower limit is somewhat
theoretical but can be applied to the present case.
Of the areas mentioned the Hengill area is
the only producer of natural steam in large
quantities. Item (5) in TABLE I gives the cost
per unit latent heat in natural steam at 3 atmos-
pheres abs. based on a constant production and
no market for the heat contained in the resi-
dual water.
It is remarkable that the cost given in Table I
is very much on the level as the average well-
head cost per unit heat in natural gas procluced
in the U. S. A.
(b) Long-distance piping.
No paper submittecl to agenda item II. A. 3
of the Conference prescnts a general discussion
Hengill
(south)
180-220
210
500
300-700
0.30
S/Gcal 0.55
some economic data are given by Bodvarsson
and Zoéga (G/37).
This line transports a flow of approximately
8 million tons per year of water at 87° C. It
consists of two 14 inches i. d. insulated steel
pipes in a concrete conduit. The average tem-
perature drop amounts to only about 3° C. The
intake pumps operate at a maximum pressure
of 14 atm.
The effective transport of heat amounts to
approximately 240 Tcal/year (one Tcal = 1012
cal). The cost of transportation computed on
the basis of present prices is approximately
1.45 $/Gcal.
(ii) The Krysuvik-Reykjavik pipeline. Bod-
varsson and Zoéga (G/37) furnish a few data on
a projected pipeline connecting the thermal
area at Krysuvik to the city of Reykjavik. The
total length of the line is 30 km which is de-
signecl as a single 16 inches i.d. insulatecl steel
pipe without a concrete conduit.
The pipeline is projected for a transport of
approximatelv 6 million tons/year of purified
57
Reykjavik Reykir
°C 80-138 80-96
114 87
Liters/sec 134 350
Meters 300-2.200 100-400
$/Gcal 0.48 0.39