Environmental Engineering Reference
In-Depth Information
During times of low wind power, a lot of electricity must be generated by the
CHP plants to accommodate for the shortfall power production. As a result, a lot
of hot water is also being produced from the CHP plant as seen in Fig. 19a. The
high production of hot water means that production is now greater than demand,
and consequently, hot water is sent to the thermal storage. Conversely, at times of
high wind power, the CHP plants produce very little electricity and hot water.
Therefore, there is now a shortage of hot water so the thermal storage is used to
supply the shortfall, as seen in Fig. 19b.
4.10.2.1 Disadvantages of TESS
Similar to the HESS, the primary disadvantage with a TESS is the large investments
required to build the initial infrastructure. However, the TESS has two primary
advantages: (1) the energy system effi ciency is improved with the implementation
of a TESS. CHP production is approximately 85-90% effi cient while conventional
power plants are only 40% effi cient, and (2) this technique has already been imple-
mented in Denmark so it is a proven solution. On the negative side TES does not
improve fl exibility within the transport sector like the HESS, but this is inferior to the
advantages it possesses. Therefore, in summary, the TESS does have disadvantages,
but these are small in comparison to the advantages.
4.10.2.2 Future of TESS
Due to the effi ciency improvements and maturity of this system, it is very likely
that it will become more prominent throughout the world. Not only does it enable
the utilization of more intermittent renewable energy (such as wind), but it also
optimises the use of fuel within power plants, something that will become critical
as biomass becomes more prominent. This system has been put into practice in
Denmark which has the highest wind penetration in the world. In addition, Lund has
Wind Power
Wind Power
Electricity
Demand
Electricity
Demand
CHP Plant
CHP Plant
Hot Water
Demand
Hot Water
Demand
Thermal Storage
Thermal Storage
(a)
(b)
Figure 19: Energy system with district heating and thermal energy storage during:
(a) a low wind scenario and (b) a high wind scenario.
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