Cradle to grave life cycle assessment of an air to water heat pump : case study for the Lebanese context and comparison with solar and conventional electric water heaters for residential application

Abstract

Our country is facing several challenges across many areas. These all have something in common: a lack of clear initiatives and norms. In the energy sector, it is important to work towards achieving a sustainable energy supply. One rising solution is renewable energy. This energy is highly available and ready to be used. This study aims to further nourish the renewable energy initiative in Lebanon, more specifically to introduce the air source heat pump (ASHP) technology. This technique uses ambient air, even when it is at a really low temperature, to heat water. In order to study the environmental impacts of the ASHP, the life cycle assessment (LCA) methodology is used. An LCA analysis provides a clear and specific understanding of the environmental impacts of a product throughout its life cycle. Moreover, an ASHP that will soon be installed in Lebanese households through ALBINA Company, is chosen as the selected model. The objectives of this thesis are to i) determine and analyze the environmental impacts of the ASHP and ii) compare the impacts of the ASHP with those associated with a flat plate solar water heater (SWH) and a conventional electric water heater (CEWH). The functional unit is chosen to be "heating 416,100 liters of water to 60°C". The software used is SimaPro (version 8.3.0.0) and the impact assessment method is IMPACT 2002+. Results show that the copper pipes of the ASHP are the highest contributor to the environmental impact of the assembly (27.8%) along with the steel outside shell (27.5%). Moreover, the refrigerant inside the pump is the highest contributor to ozone layer depletion (90.25%). The life cycle results of the three systems in question show a large contribution of the use phase to the total life cycle impacts. This leads to a need for improving the refrigerant, the Lebanese electricity grid and if possible changing the material of the heat pump pipes. The comparative LCA proved that the ASHP is the best alternative due to its low power requirement during the use phase. This work encourages installations of this better alternative across Lebanons residential sector in order to mitigate harm to the environment and further improve the use of renewable energy.