A case study of multi-energy complementary systems for the building based on Modelica simulations

Abstract

The utilization of renewable energy sources and the development of energy storage technologies have enhanced the interconversion of various energy sources to slow down global warming. The building sector, as the main bearer of energy consumption, is essential for its energy saving and emission reduction. Integrating natural gas-based combined cooling, heating, and power systems with renewable energy generation facilities is an effective solution. For that, different scenarios are designed to provide energy for a specific office building and compared with the current scenario of depending only on the municipal grid. Equipment models for photovoltaic, battery, gas engine, absorption chiller-heater, and electric heat pump are created. The results show that the multi-energy complementary system has better economic and environmental characteristics, with a primary energy ratio of over 80 % and emission reduction of over 17 %; the advantages of configuring the unit capacity to meet the cooling and heating loads for 80 % of the year are obvious, and in this scenario abandoning battery storage has higher economics for users, with a static payback period from 7.3 years to 4.4 years, but the primary energy ratio decreased by 3 % and carbon emissions increased by 7.2 tCO2. It is recommended to consider the principle of gas-electricity complementarity, relying on the combined cooling, heating, and power system to meet part of the loads, with the remaining loads being supplemented by the municipal grid. The installation of batteries should be considered comprehensively based on the price of the batteries and the requirement for energy-saving and emission-reduction.