Assessing the variability of UK renewables

As the UK seeks rapid increases in renewables, variability brings potential reliability and cost concerns for the future electricity system. This thesis presents statistical analysis of variability characteristics and investigates their implications through a simulation approach. Wind, solar and tidal current resources are considered with a regional focus on the Bristol Channel area. A preferred mix of renewables is proposed. Five separable variability impact areas are identified, noting implications for different stakeholders. Previous studies typically place emphasis on the existing energy system and on low renewables penetrations, with balancing cost and capacity credit attracting greatest attention. By focussing on underlying resource characteristics, this thesis identifies different limitations and priorities for energy system development. Supply duration gains significance at higher penetrations and curtailment will impose ultimate economic limits on the penetration of renewable energy. Limited benefit is seen from purported advantages of renewable availability patterns, described here as supply shape. Variability is a complex concept that cannot be defined by a single property, with different resources exhibiting different characteristics. Much existing representation of variability effectively describes persistence. This thesis extends analysis to statistical distribution and frequency characteristics, as well as giving consideration to predictability. Both analytical and simulation techniques are needed to fully explore variability characteristics and system impacts. Simulation is particularly necessary for investigating curtailment and supply duration. Together these complementary approaches show statistical distribution is more relevant to explaining curtailment than correlation. Of single resources in the regional case study, tidal current can achieve the highest penetration with the lowest curtailment. Optimum penetration can be increased by introducing both wind and solar as well as introducing small volumes of energy storage. An energy system wholly reliant on variable renewables is considered unfeasible as this would lead to excessive curtailment or require high storage volumes with accompanying low storage utilisations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo