Energy & Wetlands Research Group, Center for Ecological Sciences [CES],
Indian Institute of Science, Bangalore, Karnataka, 560 012, India
Web: http://ces.iisc.ernet.in/energy, http://ces.iisc.ernet.in/foss
E Mail: cestvr@ces.iisc.ernet.in; ganesh@ces.iisc.ernet.in
Corresponding Author: T.V. Ramachandra

Introduction

Electric energy accounts for the major part of total energy consumption in India. Electricity plays a pivotal role in all sectors of the society, which significantly contributes to the human comfort, industrialisation and economic growth of the region [1]. Electricity has wide range of applications as it is clean and easier to transport and convert. Per capita electric energy consumption in India is about 879 kWh (2012) and the source of electricity generation plays a significant role in energy management and conservation. Electricity generation has been largely dependent fossil fuels (coal) which are mostly centralized. Centralized generation and sparsely located loads are the prime reasons for un-electrified rural households with higher transmission and distribution (T & D) losses. Electrical power transmission and distribution network encounters higher losses (~24%) compared to other countries (China-6%, Australia-5%, Bangladesh-10%, Germany-4%) and world average (~10%) due to un-metered electricity supply, un-authorized expansion, theft and pilferage at the distribution side [2]. Decentralized generation (DG) with micro-grid are technically feasible and economically viable options to reduce the T and D losses. It also optimises locally available RE sources, stabilises the voltage, improves power quality, assists remote area electrification, reduces pollution and hybridisation of RE sources would promise a reliable supply of electricity. Utilisation of renewable energy (RE) resources for electricity generation not only brings down the greenhouse gas (GHG) emission, but also addresses energy deficiency issues. Demand for electricity has increased manifold due to urbanisation, industrialisation, etc. [2]. This cumulated demand causes the peak load on generating stations and also stresses the transmission lines. Any failure in generation or line outage will keep the load out of service or may lead to cascading of line outages. Blackout affects human comforts and economy of the country while restoring the grid. Integration of RE based generation will help in meeting the increasing peak demand on the grid which will decrease the energy demand gap [3]. Harvested electricity from RE sources can be supplied directly to the local loads bypassing the grid (Standalone generation) or can be synchronised with the existing grid (Grid integration).

Though renewable energy sources are widely available, they are intermittent and variable in nature. The potential assessment of available RE sources is essential, prior to installation of generation plants. Solar energy is one of the widely available RE resource which can be directly converted to electricity using photo-voltaic (PV) cells. Photoelectric effect is the phenomenon which generates electricity (electrons), when solar radiations fall on PV cells. Number of PV cells are connected in series and/or parallel to meet output requirement (Voltage and current). External circuit will be connected to the end user/loads through inverters (to convert DC to AC), transformers (to maintain required voltage level) and security (circuit breakers, fuses, surge arrestors etc.) components. Solar energy can also be used for thermal applications and electricity is produced through steam turbines. Solar cookers, dryers, water heaters, concentrated solar power (CSP) plants are some of the examples of thermal energy utilization. However, PV cells produce electricity from solar radiations which is more convenient for installation and user friendly [4, 5].
Wind is being used for mechanical applications such as water pumping, grinding etc. Innovation of electricity generation boosted up the wind turbine installation to generate electricity, all over the world. Currently, more than 200 GW of power is obtained from wind across countries, which is the leading RE resource. Winds are generated due to the rotation of the earth and temperature gradient in the atmosphere. Energy generation from wind is highly variable which depends on potential variability, wind speed, etc. Since the output power of the wind turbine directly proportional to the cube of the wind velocity, any variation in wind speed will cause power output deviation. Drastic changes in the output will create stress on transmission lines due to unmet loads. This also decreases the plant load factor leading to lesser electric energy supply. To avoid transmission line stressing and to keep the load connected to the grid, forecasting of available wind potential is essential in order schedule the generation. This necessitates the potential assessment of available wind resource which also will help in plant installation planning and optimised scheduling of electricity generation. Forecasting of wind speed requires extensive mathematical (probabilistic approach) modelling. High potential areas assessed from spatial data will promise certain number of high wind speed days which decreases the complexity of prediction [6, 7].
The present study deals with the available wind and solar energy potential assessment of taluks in the Western Ghats, One among 34 biodiversity hotspots in the world.  Western Ghats (WG) is a repository of diverse endemic flora and fauna and also receives higher solar insolation for about 300 days in a year. The high altitude taluks in the region experience greater wind speed which are the high wind energy potential areas. Taluks in the planes and northern region of Western Ghats (WG) receives higher insolation which encourages the solar power plant installation. Seasonal variability across the taluks and seasons have been analysed, which helps in optimising the generation and selecting the best location for plant installation. Wind energy potential compliments the lower solar insolation during monsoon in the region. This ensures the reliable electricity generation throughout the year by hybridising the energy resources.

The month wise analysis of solar and wind energy resources help in mapping the high potential regions and also to predict the probable energy output. Using the available renewable potential in the states, it is estimated that the annual electric energy demand and the peak power demand can be met by installing solar and wind power plants in the fraction of available waste land. Renewable energy sources require more land area compared to conventional power plants. Rooftop SPV installation and utilisation of feasible wasteland in the region can address the land requirement issue [8]. This also avoids aggregation of generation plants at a particular region and promotes dispersed generation. Present centralised electricity generating plants are located far away from remotely located load centers. Due to this, length of the transmission and distribution (T & D) line increases and leads to higher infrastructure cost and T & D losses. Distributed generation through micro-grids in the load centers, would reduce the distribution losses and also the sudden aggregation of load on central generating stations. Location and capacity optimisation can be done with the help of pre-assessed energy potential data of the particular region. Hence, regional level energy potential assessment is the primary step to build micro-grid architecture, to decide high energy potential region and to optimise the hybrid energy generation to ensure the reliable generation of electric energy [9]. The study exclusively discusses the renewable energy potential assessment using spatiotemporal data using open source GIS (Geographical Information System) platform.