Reliable access to electricity is a basic precondition for improving people’s lives in rural areas, for enhanced healthcare, education, and for growth within local economies as well as to meet millennium development goal in 2018. At present, more than 70 per cent people in India do not have access to electricity in their homes. Almost all of these people live in rural areas; most have scanted prospects of gaining access to electricity in the near future.
Energy is a key component of any poverty eradication and sustainable development strategy and is critical to the achievement of the millennium development goals. Better access to sustainable energy service for rural people in India is prerequisite for the sufficient supply of lighting, communication systems, and the development of income generating activities as well as the improvement of the public health situation. Today, it is widely accepted that renewable energy system (RES) have a large potential to contribute to the strengthening and development of national sustainable energy infrastructure in many countries in the world by securing better energy independence through the mobilisation of domestic renewable energy resources especially in rural areas.
The Indian Government tried to connect this rural location by using national grid extension for the last two decades. However, still the current electricity access is below 50 per cent and the real connection is less than 14 per cent. In this scenario, the rural people who have very low load demand with dispersed settlement will not get electricity in the near future. India being rapidly growing economy with an average GDP growth rate projected around six per cent over the past two decades; still the development aspect of rural areas is yet alarming. Though country have got a vast hydro electric potential but due to major river water distribution conflicts these cannot be harnessed.
Thus, in order to promote the development in remote areas there is a requirement to develop a sustainable and efficient energy system to deal with the persistent electricity problems in these areas. With cutting edge growth in renewable energy sector, these can be viewed as a potential solution for current situation, infact hybrid systems could be look forth as a prior solution to such kind of issues. The present generation capacity and estimated potential has been estimated in the table 1.
Table 1: Installed capacity of renewable energy sources in India
Presently, scientists and engineers around the globe have been supporting the utilisation of renewable energy resources. Since these are abundant, though dilute and variable, locally available, almost and don’t contaminate the environment, simplicity in onsite generation. Since, it is dilute and variable in nature, many complexities exist in conversion, condition, control, coordination etc. They are utilised as a standalone system serves many applications i.e. lighting system, water pumping for irrigation, traffic control etc. But it is costly, unreliable, and requires individual conditioning and controlling units. In this challenging atmosphere, hybrid energy system (HES) is one of the feasible solutions to harvest energy from renewable energy resources.
Overview of Hybrid Renewable Energy Systems
Hybrid energy system usually comprises of two or more renewable energy sources combined in such a way to provide an efficient system (Figure. 1). In other words, it can be said that hybrid energy system is a combination several (two or more) energy sources with appropriate energy conversion technology connected together to feed power to local load or grid.
Since, it is categorised as a distributed generation system, there is no unified standard or structure. It is beneficial in terms of reduced line and transformer losses, reduced environmental impacts, relived transmission and distribution congestion, increased system reliability, improved power quality, and increased overall efficiency.
Types of Hybrid Renewable Energy Systems
Consider a load of 100 per cent power supply and there is no renewable system to fulfil this need, so two or more renewable energy system can be combined. For example, 60 per cent from a biomass system, 20 per cent from a wind energy system and the remainder from fuel cells (Figure 2). Thus, combining all these renewable energy systems may provide 100 per cent of the power and energy requirements for the load, such as a home or business.
Another example of a hybrid energy system is a photovoltaic array coupled with a wind turbine (Figure 3). This would create more output from the wind turbine during the winter, whereas during the summer, the solar panels would produce their peak output. Hybrid energy systems often yield greater economic and environmental returns than wind, solar, geothermal or trigeneration stand-alone systems by themselves.
Solar-Induced Hybrid Fuel Cell from Biomass
Researchers have developed a new type of low-temperature fuel cell that directly converts biomass to electricity with assistance from a catalyst activated by solar or thermal energy. The hybrid fuel cell can use a wide variety of biomass sources, including starch, cellulose, lignin — and even switchgrass, powdered wood, algae and waste from poultry processing.
A new solar-induced direct biomass-to-electricity hybrid fuel cell can operate on a variety of fuels. The fuel cell, shown on the right (Figure 4), relies on a polyoxometalate (POM) catalyst (shown in the vials) which changes colour as it reacts with light.
Electrons in the biomass (Figure 5) can be transferred to polyoxometalate (POM) under sunlight irradiation, and reduced POM can deliver the charges to the anode. These electrons are then captured by oxygen in the cathode.
Completely Renewable Hybrid Power Plant
Completely Renewable Hybrid Power Plant (solar, wind, biomass, hydrogen) a hybrid power plant consisting of these four renewable energy sources can be made into operation by proper utilisation of these resources in a completely controlled manner (Figure 6).
One of the fastest expanding sources of renewable energy is the wind energy. The stand-alone wind energy systems may not be able to cater the demands of specific loads owing to the low wind speeds and high unpredictability concerns. A wind-hybrid energy system comprises of the wind energy system combined with one or more other renewable energy systems and a suitable backup system in the form of batteries bank or diesel generator. Combined operation in the form of hybrid system (Figure 7) enhances the reliability and compensates for the drawbacks perceived in stand-alone systems.
Rural areas in India amounts to about total land area of country and about 75 per cent of population of country reside in these areas. The living condition here are very unhealthy and people lack here basic facilities like electricity, water supply, education, roads etc. In order to bring people living in these areas in mainstream and to prevent large scale migration from these areas to metropolitan cities, we need to develop some sources that can fulfil their basic needs amongst them vital classification to be electricity. And in this case hybrid renewable energy systems can prove to be a major cutting-edge solution for these problems.
The classification of suitability of various techniques in hybrid renewable energy sources (HRE) given in table 2 could prove to a solution and in what type of region on the basis of geographical pattern and location of that particular region. The suitability of different systems on basis of the geographical features is mentioned in table 2.
Though hybrid energy systems could be potential solutions for the electricity problems in the rural region yet vast research is needed in this aspect to make it technically feasible to be employed at these areas. The prime focus of study should be the cost of the system and its output.