Environmental Engineering Reference
In-Depth Information
19.2 The Kemi River as a Hydropower Source
Today, the single most prominent use of the Kemi River is the production of hy-
droelectricity. There are currently eighteen major hydropower plants in the water-
shed ( Figure 19.1 ), sixteen of which are owned and operated by a single company 3
and a further power station is planned. In addition to the power plants along the
course of the river, other plants are situated at lakes and reservoirs, which enable
the electricity company to regulate the river's flow both on a daily basis and over
the course of the year. The company produces almost one third, 31.4 percent in
2007, of Finland's hydroelectric power, which altogether amounts to roughly 18
percent of the national electricity production (Kemijoki Group 2008, p. 10). More
important than the absolute amount of electricity produced, however, is the dis-
tinctive feature of hydropower in the overall mix of electricity production: the
amount of water that is allowed through the turbines can be instantaneously regu-
lated in order to adjust the production to match the current consumption of energy.
While nuclear or coal-powered electricity plants provide high overall output, their
production is very slow to adjust and impossible to fine-tune.
From a 'control room', situated in the headquarters of the hydroelectricity
company in the provincial capital Rovaniemi, such regulation and fine-tuning is
supervised. Adding to the automatic adjustments of the individual turbines to the
slightest changes in the electricity network, the engineers 4 in the control room as-
sign distinct production targets to the power plants in the watershed, which, when
totalled, meet the overall demand for every individual hour of the day ( Figure
19.2 ). Typically, the turbines are nearly closed down during the night, produce a
lot of energy in the morning, slightly reduce the production towards midday, and
peak a second time in the afternoon to then decrease production again for the
night. At night, electricity production tends to drop off to around ten percent of the
daytime maximum. Moreover, less hydroelectricity is produced during the week-
ends than during weekdays. To what extend the turbines produce electricity is cen-
trally determined from the control room. Although the individual power stations
are staffed for part of the day, this is only for monitoring and maintenance work -
electricity production is steered from Rovaniemi.
3
In fact, this company has recently taken to steering electricity production even at the two
major power stations owned by another company. The electricity output of those two sta-
tions is credited to the owning company, but their regulation is achieved in accord with
the long chain of other hydropower stations on the river. There are three smaller hydroe-
lectric power stations with minor capacity in the Kemi River watershed, located at lakes
on small tributaries. They are owned by different power companies and will be disre-
garded for the present analysis.
4
Although I use the term 'engineers' when talking about the personnel in the control
room, not all of them are in fact engineers. Two of the senior employees are actually a
mathematician and a former electrician, respectively.
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