The global EV stock is expected to increase from 7.2 million in 2019 to nearly 140 million vehicles by 2030. So, the demand for the battery also increases due to the increase in the number of EVs. In any EV, battery degradation is an unavoidable phenomenon and EV batteries are assumed to arrive at their end-of-life in EV application when the state of health reaches 80 %, repurposing the eligible EV batteries after end of first life is expected to extend their lifetime by another 5-15 years in the second life applications.  This thesis aims to conduct a techno-economic study on the usage of second life EV batteries as an alternative storage option in off-grid PV systems compared to lead-acid batteries and new Li-ion batteries. A single-family house with an annual demand of 2245 kWh/year located in Athens was chosen as the primary location, the off-grid PV system is pre-sized for Athens and based on the pre-sizing results and what is state of art in the market. The system components were chosen for system design (4 kW bi-directional inverter, 2.9 kW PV array, 7.2 kW genset and three battery bank options i.e., 16.5 kWh of lead-acid, 8 kWh new Li-ion and 12.6 kWh of second life EV battery). PV off-grid system with different storage options is simulated using HOMER for both locations and the results are compared.   The simulation results show that the designed off-grid PV system can reach a solar fraction of 90 % in Athens and 73 % in Gotland when 16.5 kWh of lead-acid batteries are used with an allowed depth of discharge of 50 %. When a new Li-ion battery of 8 kWh with an allowed depth of discharge of 80 % is used then the achievable solar fraction is 84 % in Athens and 71 % in Gotland, When the second life EV battery of 12.6 kWh with an allowed depth of discharge of 60 % is used then the achievable solar fraction is 90 % in Athens and 74 % in Gotland. Sensitivity analysis is performed on the depth of discharge and results showed that the solar fraction can be increased by allowing the battery to discharge more, but it also decreases the battery lifetime.   The simulation results also show that the net present cost was lower in Athens for all the reference cases compared to Gotland. Net present cost and levelized cost of electricity for the off-grid system are 25.3 k€, 0.9 €/kWh in Athens and 29.2 k€, 1.0 €/kWh in Gotland when a lead-acid battery is used. When a new Li-ion battery is used then 26.2 k€, 0.9 €/kWh in Athens and 29.3 k€, 1.0 €/kWh in Gotland, when the second life EV battery is used then 26.7 k€, 0.9 €/kWh in Athens and 30.7 k€, 1.1 €/kWh in Gotland.   Overall, the net present cost and levelized cost of electricity are lower in Athens in all cases compared to Gotland. For the reference house in Athens, lead acid battery system has shown slightly lower net present cost than new Li-ion battery and second life EV battery. For the reference house in Gotland, both lead acid battery and new Li-ion battery system have shown similar net present cost and they are slightly lower than second life EV battery.   Also, the second life EV battery levelized cost of electricity is fairly comparable to the new Li-ion and lead acid battery system. In future, the massive inflow of used batteries from EV are expected to be available on the market for the second life application at a lower price than today. Thus, in future, second life EV batteries can become economically viable.

In-situ resource utilization and in-situ manufacturing are being actively pursued as ways to enhance the development of human activities in space. However, the re-purpose of space systems through processes like recycling, re-manufacturing, and re-use, has not received the attention it deserves given its potential to reduce the waste generated by human activities in space, improve the sustainability of space habitats, and reduce the environmental impact on Earth of human activities in space.  This dissertation explores the available life cycle analysis methodologies in order to understand how the industry treats and measures re-purposability, and what re-purposing enabling technologies are available or under development, and proposes the use of the embodied energy and derived metrics to: quantify the waste generated by a space system when reaches its end of life, how re-purposable a space system is, and how valuable the outputs of the re-purposing process are for the habitat were the system is being processed. This data can then used to provide feedback regarding manufacturing process and material selection for the design, enabling a systems architect to optimize it with re-purposability in mind.  This Design to Re-purpose methodology (DTR) is tested through the analysis of selected components of an Lunar Habitat design from Hassell Studios, to the extend possible given the early state of the design, and with some assumptions regarding the expected repurposing technologies available. It demonstrated that performs as expected for the scenario provided, and yielded useful material selection feedback, including how the value of the re-purposing output material can infuence the design to optimize its re-purposability and the subsequent value it provides to the habitat.  Further development of this methodology is necessary, as well as additional testing especially considering scenarios where the initial system is not built on Earth, for which a preliminary road map was laid down.