A Prototype Model for Pumped Hydro Storage of Off-Grid <10KW Photovoltaic and Wind-Energy

Abstract

Through hands-on experimentation and spreadsheet modeling, this project examines the potential of pumped-hydro storage of renewable energy sources as potentially being more cost effective than standard lead-acid and lithium-ion battery storage systems. The research question addressed is whether a gravity fed water storage system a feasible, more cost effective and more sustainable storage solution for small (<10kW) photovoltaic and wind renewable off-grid energy hybrid systems in comparison to more traditional battery storage systems? I hypothesize with adequate sizing, an uphill gravity storage system will be more cost effective over a 30-year period, than a lead-acid battery (or other battery) storage system for an off-grid hybrid solar and wind energy production system. After calculating the energy requirements for my 20-acre off-grid homestead in north-east Washington state, experiments were conducted to determine the most cost effective and energy efficient means of solar and wind renewable energy production. Three different renewable energy storage systems including lead-acid battery, lithium-ion battery and pumped-hydro storage were also experimented on to changing variables to determine the most cost effective and energy efficient means of energy storage. Through my analysis, I determined that a gravity fed pumped-hydro storage system for renewable energies is more cost effective than traditional battery storage systems as well as more cost-effective than tying into the traditional local utility grid system due to the remoteness of my homestead location. This spreadsheet model has the potential to be used on a situational basis to determine the potential cost-effectiveness of government subsidized renewable energy projects in lieu of standard grid connectedness for remote communities.