Life Cycle Assessment of a Reversible Heat Pump–Organic Rankine Cycle–Heat Storage System with Geothermal Heat Supply

Abstract

The life cycle assessment of components is becoming increasingly important for planning and construction. In this paper, a novel storage technology for excess electricity consisting of a heat pump, a heat storage and an organic rankine cycle is investigated with regards to its environmental impact. Waste heat is exergetically upgraded, stored in a hot water storage unit and afterwards reconverted to electricity when needed. Such a pilot plant on a lab scale is currently built in Germany. The first part of this paper focuses on geothermal energy as a potential heat source for the storage system and its environmental impact. For a large scale application, geothermal hotspots in Germany are further investigated. The second part analyzes the storage technology itself and compares it to the impacts of commonly used battery storage technologies. Especially during the manufacturing process, significantly better global warming potential values are shown compared to lithium-ion and lead batteries. The least environmental impact while operating the system is with wind power, which suggests an implementation of the storage system into the grid in the northern part of Germany.

Keywords

• life cycle assessment
• heat pump
• organic rankine cycle
• heat storage
• electricity storage
• geothermal energy