Grid Stabilization Effect of Combined Electricity Generation from Wind and Photovoltaic Systems in Murcia, Spain

Introduction

Nowadays, industrial and urban development are mostly driven by fossil fuels thus creating important environmental problems, being green-house-gases (GHG) emissions the best known. Alternative resources in power generation are being developed with the aim of meeting the increasing demand of energy but at the same time reducing the GHG emissions: renewable energy technology is the best choice for this purpose. Within the broad range of renewable options, wind and photovoltaic technology have been the most rapidly growing technologies worldwide. The electricity generation mix of any country in the world is increasingly incorporating a larger contribution of renewable energy supply (International Energy Agency, 2012; European Commission, 2013; Red Eléctrica Española, 2013). The electricity grid of such countries needs to match in real time the supply and demand of electricity, i.e. the electricity injected to the grid at a given time has to be the same as the electricity consumed by the users at the same time (European Commission, 2013). This is a challenge when renewable sources represent a large share of the electricity mix, and the road toward sustainability will require management of different intermittent sources probably with a storage back-up (International Energy Agency, 2012). This matching is usually guaranteed by the grid manager, which has the authority to allow or block the electricity input to the grid from different suppliers, and usually prioritizes generation from renewable sources. It has been alleged that a large amount of renewable electricity supply could become unmanageable because it depends strongly on uncontrollable environmental parameters such as wind speed or irradiance, which may vary strongly with geographical location or time (during same day or seasonal variations) (Prescott, 2004). Nevertheless, contrary to these allegations, a larger input of renewable energy, in particular from wind and photovoltaic sources in a given geographical region of large enough size can have a stabilizing effect to the grid (Chu, 2012), even for PV-only integration (Lund, 2006; Marcos, 2012). In order to benefit from this complementarity, a careful selection of the best location for installing the energy system is required.