This tutorial demonstrates the evaluation of different heat and power generation systems using the TOP-Energy components Key Figures. The key figures CO2 Factor, Primary Energy Factor, Levelized Cost of Energy, and Self Sufficiency Rate are considered separately for electricity and heat generation.
Reference Case
In the reference case, the electricity demand of a small beverage producer amounting to 470.25 MWh/a is completely covered by the Electricity Supplier. The annual heating energy demand of the plant of 2121.4 MWh is covered by a gas boiler with the help of a Fuel Supplier. The simulation considers a Heating Limit temperature of 15 °C.
The CO2 Factors for heat and electricity assume relatively high values of 223.33 g/kWh and 427 g/kWh, respectively, due to the emissions.
The Levelized Cost of Energy are market-based due to the absence of revenues, captive production, and conversion facilities.
Variant 1: Photovoltaics and Solar Thermal Systems
Using a Photovoltaic system to generate electricity and Solar Collectors to provide heat lowers the Levelized Cost of Energy. The use of renewable energies reduces the CO2 Factor compared to the reference case. The key figures CO2 Factor (-1.0598 g/kWh) and Primary Energy Factor (-0.0044675) related to electric power are negative, because the PV system feeds a larger power into the grid than the system receives from the Electricity Supplier. The Self Sufficiency rate related to electricity and the Self Consumption Rate (electricity) each reach a value of about 40 %. Because the excess heat cannot be utilized here, the operating mode is set to controllable.
Variant 2: Expansion by Storage Systems
To compensate the fluctuations in the energy supply by renewable energies, it makes sense to use storage systems. In order to realize the use of the storages, Priority components are used in TOP-Energy.
Surplus electricity can be fed into the power grid of the electricity supplier, but the remuneration is lower than the electricity price. A storage system reduces the Levelized Cost of Energy, increases the Self Sufficiency Rate and and the Self Consumption Rate. The Primary Energy and CO2 Factors related to electricity are in the positive range, but close to the value of 0, which is considered climate neutral. The Primary Energy and CO2 Factors related to heat demand are even lower than in variant 1.
Variant 3: Photovoltaics, Storages, Heat Pump
In variant 3, the solar thermal system is omitted and a Heat Pump is used instead. The heat pump can reduce the use of fuel and thus CO2 emissions, reducing the CO2 Factor. Overall, CO2 emissions are lowest in this variant. The Levelized Cost of Energy (104 EUR/MWh electricity and 54 EUR/MWh heat) and the Primary Energy Factor (0.957 for electricity and 0.55898 for heat) are lower than in the reference case, but not lower than in the other variants. The Self Consumption Rate increases to 64 % due to the electricity demand of the heat pump, which is partly covered by the electricity generated by the PV system, and is thus higher than in the other variants. As a result of the additional demand, the total electricity demand and thus the grid purchase increase. The Self Sufficiency Rate related to electricity has the lowest value of the variants at 30 %, whereas the self sufficiency rate related to heat has the highest at 56 %.
Comparison of Variants
In the Variant comparison, the economic and ecological characteristics of the variants and the reference case are shown in the Overview (see following figures).
