Technological measures needed for 100% renewable electricity system in Lithuania and feasibility of their future competitiveness

Abstract: This study aims to improve understanding the role of energy storage and other technologies in enablingeconomically competitive variable renewable energy based power systems which hold promise to minimiseenvironmental, energy security and other externalities of existing systems. The study focuses on insulatedLithuanian power system, which does not rely on other non-renewable systems to operate, 100% suppliedby renewables with at least 80% of that from solar and wind. Hourly time resolution is used for duration ofone year.Simple analysis, which does not rely on optimisation model, was performed using only final consumption,wind and solar power production data. It indicated seasonal energy shortages significantly varying betweenthe years and accounting up to a quarter of cumulative hourly shortages or more than 8% of the annual finalconsumption.The model developed in this study optimises the annualised system costs, while balancing consumptionwith production at each hour of the year under various constraints. Both installed capacity and its dispatchare varied. The model is deterministic with linear formulation and is run using GAMS and MatLab software.Six technologies are included: onshore wind, solar, biomass, hydro, pumped hydro and power-to-powerstorage systems. Wind and solar installed capacities and hourly output are scaled proportionally fromreference year values. Curtailment is not restricted. Biomass annual electric output is limited by its amountin the reference year. Hydro and pumped hydro are modelled based on two large existing plants in thecountry. They are the only technologies which capacity cannot be increased. Power-to-power storage systemis further divided into three systems (power to hydrogen, hydrogen storage, hydrogen to power) and aresized independently. Different technologies used for these systems depending on scenario. Four scenariosanalysed address possible differences in technology availability as well as economic environment. Majorsimplifications used in the model and their expected impact on overall system costs are listed and brieflydiscussed.Model runs result in system costs being 2.9 to 5.3 times larger than electricity purchase costs of the countryin a reference year from existing wholesale market. Majority of these costs are for wind and solar capacitywhich covers not only final demand, large losses in storage systems, but is also oversized resulting incurtailed surplus levels of 11% to 46% depending on scenario. Sensitivity analysis was performed runningmodel for different wind and solar costs up to 5 time lower than their current values. Extrapolated trendsshow wind cost reductions having larger impact and that 6.2 to 8.3 times lower wind costs would be neededto get system costs lower than what was paid for electricity in the wholesale market during the referenceyear.Given limited number of technologies considered and isolation of the system large cost reduction potentialwith existing technologies is expected. Four most promising model expansion areas are analysed, which add:more storage technologies, neighbouring Latvian power sector, heating sector, more detailed biomasspotential representation. Work validity, applicability in other county cases and even further directions forfuture work directions are discussed.A paper summarising this work is submitted and accepted for presentation in 17th Wind IntegrationWorkshop in Stockholm. It can be found as an appendix at the end of this report.