Samuli Rinne

Optimization of energy production of a CHP plant with heat storage

Combined heat and power (CHP) production is a very efficient technique to produce power and heat in an integrated process. In CHP plants, generation of heat and power follows a joint characteristic, which means that production planning of both commodities must be done in coordination. The hourly produced power can be sold to the grid at market price, but heat must be produced to meet the local demand of district heating or heat for specific industrial processes. Typically, the most profitable operation of a CHP system can be planned by using an optimization model. The high efficiency and profitability of CHP plants can be further improved by utilization of energy storage units. Heat storages make it possible to relax the constraint to produce heat each hour to exactly match the local demand. This allows satisfying the variable heat demand more cheaply by storing heat during low demand and discharging heat when demand is high. By relaxing the connection between heat and power production, heat storages also allow producing more electricity to the power market when the spot price is high and reducing the power generation when spot price is low. The aim of this study is to develop a model for optimizing the operation of a CHP plant together with a heat storage. The model is a linear programming (LP) model consisting of hourly models connected together with dynamic storage constraints. The objective is to minimize the production (fuel) costs subtracted by revenue from selling power to the market. The model is demonstrated using modified reallife data of a Finnish city. The results are useful for planning efficient operation of the plant. The model can also be adapted for determining the optimal size of the storage.

Open district heating for Espoo city with marginal cost based pricing

We present the concept for an open district heating market for cities with hourly marginal cost based pricing, using the Finnish city of Espoo (265 000 inhabitants) as example. District heating (DH) with highly efficient Combined Heat and Power (CHP) production covers about 90% of heating in larger cities in Finland. We created a model with an hourly resolution, where the power plants are dispatched in the cost optimal order according to representative fuel prices and electricity spot market prices. We explored the impacts of external producers on the system operation and possible system cost savings induced by allowing external producers to provide their waste heat to the network, simulated by 20 MW waste heat production of a large metro and shopping centre. Similarly, the impacts of a large solar heat plant (5 MW) were simulated. Our results demonstrate that open heat market could be beneficial for all parties and that significant cost and fuel savings are possible with mutually beneficial business models.

Opportunities of bioenergy-based CHP production in balancing renewable power production

This paper considers opportunities of bioenergy-based combined heat and power (CHP) to balance fluctuation in solar and wind power. The paper studies participation of CHP production in an electrical power reserve, which provides opportunities to integrate more renewable energy production into the electrical system and also makes it possible to raise the profit of the CHP operator. Moreover, the paper discusses certain aspects of integrating heat pumps (HPs) with a CHP plant and participation of their combination CHP in electricity reserve power markets.

A concept to combine the different housing alternative advantages

Purpose – A dense urban structure cuts down traffic emissions. It also promotes waste heat use and storage possibilities as a form of district heating. However, quality elements associated with detached houses, such as tranquillity and self-expression possibilities, may be lost. Better building quality and alternatives to private car use can enable these elements in smaller spaces, which is assessed here. The paper aims to discuss these issues. Design/methodology/approach – A technology set for an imaginary high-quality (HQ) apartment house is discussed by assessing increased embedded energy of the building structure, due to the HQ measures. HQ solutions include visual barriers, increased sound insulation, roof terraces, large windows, apartment adaptability, bike sheds, electrical cargo bikes and advanced energy solutions. Findings – The increased construction and heating energy use in HQ buildings can be offset if car use is reduced by 10-15 per cent. There is a greater possibility of achieving this reduction if HQ housing can make urban densification more readily acceptable by demonstrating, that good quality housing can exist both in smaller building lots as well as in smaller apartments. Originality/value – The quality issue brings a novel perspective to estimating the environmental impacts of built environment solutions. The approach here is quite simple, but the issue can be discussed more. That is, how much total resource input can be decreased, if the target is not to produce square metres but rather the necessary elements to have a good quality of life.