Environmental Analysis of Integrating Photovoltaics and Energy Storage in Building

Abstract

The energy consumption of buildings accounts for approximately 36 % of the final energy consumption in Europe, being the largest end-user. The UK government has committed to cut greenhouse gas (GHG) emissions by 100 % below 1990 levels and bring all GHG emissions to net-zero by 2050.To support the realisation of these goals the concept of an Active Building was formulated which refers to any building type, such as factories, offices, homes, and other structures in the built environment, which are equipped to conserve, generate, store, and release energy. The increasing deployment of rooftop photovoltaics drives the growth of energy storage to capture solar energy for later use in buildings. The Active Office was built at Swansea University, UK in 2018 and is a two-story office building. Its energy demand, including that of electric vehicle charging, is primarily met by the 23 kWp of building-integrated photovoltaics (BIPV) and 110 kW of lithium-ion (Li-ion) batteries. When the BIPV and batteries are unable to meet the demand, electricity supplied from the grid can be used.The objective of the research is to assess the potential environmental impacts of the building energy system of BIPV and Li-ion batteries, as well as to address the lifetime and degradation of Li-ion batteries, and the associated consequences. Life cycle assessment (LCA) is employed in this research. Three operational strategies are designed regarding the interactions between the electrical grid, BIPV, and Li-ion batteries. In the best case operational scenario, using a rolling average to predict building generation and consumption, the GWP from the building operation is 33 g/kWh which is a 5 fold reduction compared with the grid emissions of 170 g/kWh. The worst case building operational strategy creates emissions of 128 g/kWh, it is still an improvement upon electricity supply by the national grid alone. This analysis demonstrates that operational strategy optimisation can reduce the environmental impacts of the Active Building concept compared with using grid electricity alone.