Planning subtask C1: Identification of alternatives
Example: Local energy planning in Hylkje

The approach to increase the capacity of the local electricity distribution system - in order to be able to accommodate new customers, is compared with the approach of using gas as local energy source and hot water as energy carrier in a new, parallel district heating infrastructure. Four investment planning alternatives have been selected for further investigation.

The first alternative consists of reinforcing the electricity grid with a new supply line to the area, so that one can continue to rely on electricity to supply the local stationary energy demand. A district heating network and a CHP plant is built in the other three alternatives, to supply the heat to the customers in the residential area. In addition, a gas boiler is built to meet the peak demand for district heating.

In the second alternative, the district heating network also covers the industrial site outside the residential area. The CHP plant is placed at the industrial site, and can also meet the heat demand there, which is currently supplied with a diesel boiler.

In alternatives 3 and 4 the CHP plant is placed nearby the residential area. The only difference between these alternatives is the size of the CHP plant. The larger CHP plant in alternative 4 facilitates generation of more electricity, which can be sold to the electricity market when it is profitable to do so. A consequence of higher electricity generation might be excess heat from the CHP plant, which must be dumped to the local surroundings.

The following table summarises the four alternatives considered for analysis in this planning example:

Alternative

New el line

DH network

CHP plant

Gas boiler

1 yes no no no
2 no large 3.6 MW 5.0 MW
3 no small 3.6 MW 5.0 MW
4 no small 5.0 MW 5.0 MW

Published August 3, 2012

Contact: Gerd Kjølle, SINTEF Energy Research