Location
Description
The district heating and cooling (DHC) system in Luleå (Sweden) supplies 31,000 households with heating and cooling on a daily basis. The heat is manly produced at a CHP plant close to the city center. It supplies the base heat production of 185 MW to the grid and gets the fuel (e.g. flue gas) from a neighboring steel plant.
During cold days and when needed there are peak load production units out in the grid at strategic places that can supply extra heat. These units are mainly using wood pellets, electricity and oil as fuel. Especially the use of oil is an expensive and non-environmentally friendly energy source and is to be used only when demand requires. The total potential heat from these units is 350 MW, which is enough to support the whole grid if the base production should fail.
During 2014-2018 Luleå Energy AB invests 45 million Euros in the DHC system due to the expansion of the city. This makes Luleå a great place to be integrated in the OPTi project when new solutions in the grid can be performed, evaluated, optimized and give important input to OPTi-Sim. OPTi-Sim facilitates a virtual representation of the real DHC system, integrating different models in a co-simulation approach.
To gain the most satisfying results four well planned pilots will be performed in Luleå. In the project a number of buildings will be test buildings where measurements on vital parameters will be performed. Measurements of vital parameters will also be performed on grid level to cover a greater area. The result will be used to evaluate and optimize OPTi-Sim and see how well the key performance indicators are fulfilled.
The four pilots are:
- Peak load reduction
In this pilot the main goal is to reduce the peak loads during the morning and evening by turning of the heat supply to the buildings and only allow heat for tap water.
- Lowered district heating system supply temperature
The main goal of this pilot is to lower the supply temperature in the district heating system. The gain from this is that the energy losses to the surrounding will be lowered and also enables increased production of electricity at LuleKraft AB.
- Limitations in the district heating grid
In Luleå one limitation is the supply of energy over the bridge from the city center to Bergnäset. From OPTi-Sim it should be possible to get suggestions in how to regulate the heat by example accumulate it in buildings or optimizing control valves in a specific matter to give the most economically beneficial solution.
- Valve optimization
In the grid there are DH centrals where control valves regulate the DH water for tap water and heating to the buildings. The valves for tap water have historically been over dimensioned which leads to oscillating tap water temperature and have negative effect on both consumers and producers. OPTi-Sim should be able to evaluate how a change of control valves to more correct size affect costumers and producers, and also see if a change is economically feasible.