While most of Colombia’s power comes from large-scale hydroelectricity generation, it still depends on fossil-fuel-based technologies. Alternative cleaner energy sources have been largely neglected despite their abundance and the likely complementarities between different renewable resources. This limited mix of energy sources has made the system vulnerable to unpredictable and recurrent drought conditions (El Nino) occurring every 4 ~ e5 years. In the past, El Nino brought high energy costs and power ~ supply losses. This paper proposes an optimisation model to study the insertion of renewable energy systems (RES) into the Colombian electricity sector. The model considers a cost-based generation competition between conventional technologies (hydro and thermal) and alternative RES (solar photovoltaic (PV) and wind). It aims at minimising system costs, CO2 emissions, and the number of blackout events. The model is solved by following two procedures known as Implicit Stochastic Optimisation (ISO) and Robust Optimisation (RO), and the results indicate that alternative renewables should replace all fossil-fuel-based technologies for economic and environmental reasons. Solar PV seems particularly promising to expand system capacity, as it contributes to both the reduction of the overall system costs and to the ability of the system to cope with extreme dry weather conditions.

Introduction

The continuous worldwide growth in energy demand, and its impacts on CO2 emissions, have prompted changes in the traditional energy production practices, moving from those based on fossil fuels to technologies based on renewables [1]. Undoubtedly, renewable energy has been one of the best strategies to reduce greenhouse gas emissions and, consequently, to mitigate global warming. Thus far, the focus of this change has mainly been on the installation of power-generation facilities, particularly solar PV and wind technologies [4,5]. In 2015, solar PV and wind power accounted for 77% of all the new power installations in the world and hydropower accounted for most of the remainder [4]. It was the first year that the power capacity added into the world came primarily from renewables, rather than from all the fossil-fuel-based technologies combined. Looking at the total power in place, renewables supply at least 23.7% of the world’s demand, with 16.6% coming from hydropower installations [5]. This growing trend towards renewables has sped up the learning curve, prompting greater technology efficiency and lower costs [6]. Solar PV and onshore wind technologies have experienced the most remarkable cost reductions in the past seven years, and forecasts predict that costs will continue to fall in the near future until they are even cheaper than conventional technologies [7,8]. It is expected that renewable energy systems (RES) will become the cheapest options in most countries around the world by 2030, and that by 2040 the costs of wind and solar PV would fall by up to 41% and 60% respectively [9]. Colombia has important coal, water, wind and solar irradiation resources (but limited established gas and oil reserves) for electricity generation. However, at present, large hydropower facilities satisfy the primary electricity demand (about 65%) and gas- and coal-fired plants contribute with the rest (about 35%).