Design of Renewable and System-Beneficial District Heating Systems Using a Dynamic Emission Factor for Grid-Sourced Electricity

Abstract

In future energy scenarios with a high share of renewable energies within the electricity system, power-to-heat technologies could play a crucial role for achieving the climate goals in the heating sector. District heating systems can integrate volatile wind and photovoltaic energy sources and resolve congestions within the electricity grid, leading to curtailment of renewable electricity generation. This paper presents a design approach for setting up system-beneficial power-to-heat-based district energy systems. Within the scope of the project QUARREE100 an existing district in the provincial town Heide in Northern Germany is examined. A linear investment and unit commitment optimization model is applied. By considering local dynamic emission factors for grid-sourced electricity, which contain information on local wind energy curtailment as well as the emission intensity of the overall electricity generation, a renewable and system-beneficial design can be derived. With this method, the minimal rated power and capacity of energy converter and storage units can be determined to achieve emission reductions with respect to minimum costs. The approach of using different methods for the consideration of the emissions of grid-sourced electricity is analyzed based on different scenarios. By using a dynamic emission factor for grid-sourced electricity, lower emissions with fewer costs can be achieved. It is shown that a dynamic assessment leads to different design decisions and far-reaching deviations in the unit commitment. The results clearly show that a constant emission factor is no longer an option for grid-sourced electricity in urban energy system models.

The use of primary energy factors and CO2 intensities for electricity in the European context - A systematic methodological review and critical evaluation of the contemporary literature

“…For example, in [83] CIs with a monthly temporal resolution are used to devise optimal renovation measures for Finnish apartment buildings, while hourly CIs are used in [22,125] to calculate the CE savings made possible by dispatching flexible loads. Elsewhere, hourly CIs are used to better calculate (and to help minimise) the CE related to HPs [52,95] and EVs [113].…”

Dynamic Prospective Average and Marginal GHG Emission Factors—Scenario-Based Method for the German Power System until 2050

“…Röder et al applying constant and dynamic emission factors (AEF fc ) in today's and future sector-coupled urban energy systems [19]. They come to the conclusion that the wider the distribution of the emission factor, the bigger is the impact whether a constant instead of a time-resolved emission factor is used [19].…”

“…Röder et al applying constant and dynamic emission factors (AEF fc ) in today's and future sector-coupled urban energy systems [19]. They come to the conclusion that the wider the distribution of the emission factor, the bigger is the impact whether a constant instead of a time-resolved emission factor is used [19]. Figure 5 shows that the range of the values is constantly over 400 g CO2eq /kWh el in all years, except for the year 2050 in the CAP scenario, thus again emphasizing the advantages of the hourly dynamic emission factors for ecological assessment methods.…”

“…The effects of demand-side management, efficiency measures, or the expansion of RES on the emissions can only be examined in detail with dynamic emission factors [13][14][15]. This necessity of varying emission factors is clearly shown in previous studies by [8,12,[16][17][18][19]. A significant error is made when the yearly average emission factor is used for the ecological assessment as long as the demand for electricity is not constant for every hour of a year [20,21].…”

“…These emission factors from historical data are used for the ecological assessment and dispatch of battery storage systems. The authors of [19] showed that it is essential for the development of low-emission local energy systems in Germany to use dynamic, rather than constant, emission factors of power production. This is the only way to achieve the emission reduction intended by sector coupling, by correctly planning the use of flexible and hybrid technologies.…”