A hybrid model of solar-wind - biomass power generation system: A review

Renewable sources of energy are playing an increasing role in the current global energy map. The public attention is focused on these renewable technologies as environmentally sustainable and convenient alternatives. In the context of conventional energy sources, this study treats the functioning of a hybrid system containing the solar panels, wind turbine and biomass fuel. An energy based modeling will be developed using Matlab/Simulink. The simulation results will be used for optimizing the configuration costs in order to obtain the most cost effective system.


I. INTRODUCTION
Renewable energy technologies offer the promise of clean, abundant energy gathered from self-renewing resources such as the sun, wind, water, earth, and plants. Virtually all regions of the world have renewable resources of one type or another. Renewable energy technologies offer important benefits compared to those of conventional energy sources. Worldwide, 1000 times more energy reaches the surface of the earth from the sun than is released today by all fossil fuels consumed. Photovoltaic and wind generation are also an attractive source of energy because of their benign effect on the environment. Increased population growth and economic development are accelerating the rate at which energy and in particular electrical energy is being demanded. All methods of electricity generation have consequences for the environment, so meeting this growth in demand, while safeguarding the environment poses a growing challenge. Each of the renewable energy technologies is in a different stage of research, development, Commercialization and all have differences in current and future expected costs, current industrial base, resource availability, and potential impact on greenhouse gas emissions. Hybrid power systems consist of a combination of renewable energy sources such as: photovoltaic (PV), solar energy, tidal energy, biomass power, wind generators, etc., to charge batteries and provide power to meet the energy demand, considering the local geography and other details of the place of installation. These types of systems, which are not connected to the main utility grid, are also used in stand-alone applications and operate independently and reliably. The best applications for these systems are in remote places, such as rural villages, in telecommunications, etc.

II. PROBLEM FORMULATION
The rapid depletion of fossil fuel resources on a world-wide basis has necessitated an urgent search for alternative energy sources to cater to the present day demands. Alter-native energy resources such as solar and wind have attracted energy sectors to generate power on a large scale. A drawback, common to wind and solar options, is their unpredictable nature and dependence on weather and climatic changes, and the variations of solar and wind energy may not match with the time distribution of demand. Fortunately, the problems caused by the variable nature of these resources can be partially overcome by integrating the two resources in proper combination, using the strengths of one source to overcome the weakness of the other. The hybrid systems that combine solar and wind generating units with battery backup can attenuate their individual fluctuations and reduce energy storage requirements significantly. However, some problems stem from the increased complexity of the system in comparison with single energy systems. More over the low efficiency of this hybrid model is another big disadvantage, on the part of energy production. The above hybrid model use batteries as its storage system, which cannot be discharge beyond 30% from the point of view of life cycle of the batteries.
• No electricity will be generated when the wind or the solar is not available. It depends upon the weather as well as geographical locations where the solar and wind is available in abundant.
• Strength of wind is not constant because it varies from time to time. This means that wind turbines do not produce the same amount of electricity all the time. • Solar energy is also not constant in the night time or during the sunny days.

III. OBJECTIVE
So taking view of above difficulties of the solar/wind hybrid model, we are introducing Biomass Energy as another generating resource accompany with the above two resources. The biomass can generate electricity at any climate conditions which can increase the overall production of the system and decrease the demand of batteries for this system. The individual efficiency of the biomass is very high which can improve the efficiency of whole new hybrid model. There are many benefits of using the Biomass energy: No Harmful Emissions: Biomass energy, for the most part, creates no harmful carbon dioxide emissions. Many energy sources used today struggle to control their carbon dioxide emissions, as these can cause harm to the ozone layer and increase the effects of greenhouse gases, potentially warming the planet. It is completely natural, has no such carbon dioxide side effects in its use. Clean Energy: Because of its relatively clean use, biomass energy, when used in commercial businesses such as airlines, receives tax credit from the US government. This is good for the environment and good for business. It does release carbon dioxide but captures carbon dioxide for its own growth. Carbon dioxide released by fossil fuel are released into the atmosphere and are harmful to the environment. Abundant and Renewable: Biomass products are abundant and renewable. Since they come from living sources, and life is cyclical, these products potentially never run out, so long as there is something living on earth and there is someone there to turn that living things components and waste products into energy. Reduce Dependency on Fossil Fuels: It has developed as an alternate source of fuel for many homeowners and have helped them to reduce their dependency on fossil fuels. Reduce Landfills: Another benefit of this energy is that it can take waste that is harmful to the environment and turn it into something useful. For instance, garbage as landfill can, at least partially, be burned to create useable biomass energy. Biomass plants have been already implemented and are running successfully all over the world.

IV. SOLAR ENERGY
Solar energy is the most readily available source of energy. It is free. It is also the most important of the non-conventional sources of energy because it is non-polluting. Fuel cells, magneto hydrodynamic systems, and devices based on thermoelectric, thermo ionic and solar-electric conversion are all potentially useful nonconventional electricity sources. Earth surface receives 1.2x10^17 W of power from sun. Energy supplied by the sun in one hour is almost equal to the amount of energy required by the human population in one year. Renewable energy sources play an important role in electricity generation. Various renewable energy sources like wind, solar, geothermal, ocean thermal, and biomass can be used for generation of electricity and for meeting our daily energy needs.

V. WIND ENERGY
Wind power systems convert the kinetic energy of the wind into other forms of energy such as electricity. Although wind energy conversion is relatively simple in concept, turbine design can be quite complex. Most commercially available wind turbine uses a horizontal -axis configuration with two or three blades, a drive train including a gearbox and a generator and a tower to support the rotor. Typical sizes for a wind turbine range from 200-750 KW, and electricity produce within a specific range of wind speed. Capital costs have declined from about $ 2.2/w in early 1980 to less than $ 1/w today. Cooperative research between DOE and manufacturing companies is aimed at increasing the aerodynamics efficiency and structural strength of wind turbine blades, developing variable speed generation and electronic power controls and using taller tower that allow access to the stronger wind found at greater height VI. BIOMASS ENERGY To many people, the most familiar forms of renewable energy are the wind and the sun. But biomass (plant material and animal waste) is the oldest source of renewable energy, used since our ancestors learned the secret of fire. Until recently, biomass supplied far more renewable electricity-or "bio power"-than wind and solar power combined. If developed properly, biomass can and should supply increasing amounts of bio power sustainable, low-carbon biomass can provide a significant fraction of the new renewable energy we need to reduce our emissions of heattrapping gases like carbon dioxide to levels that scientists say will avoid the worst impacts of global warming. Without sustainable, low-carbon bio power, it will likely be more expensive and take longer to transform to a clean energy economy. But like all our energy sources, bio power has environmental risks that need to be mitigated. If not managed carefully, biomass for energy can be harvested at unsustainable rates, damage ecosystems, produce harmful air pollution, consume large amounts of water, and produce net greenhouse emissions.
However, most scientists believe there is a wide range of biomass resources that can be produced sustainably and with minimal harm, while reducing the overall impacts and risks of our current energy system. Implementing proper policy is essential to securing the benefits of biomass and avoiding its risks. Biomass is a renewable energy source not only because the energy it comes from the sun, but also because biomass can regrow over a relatively short period of time. Through the process of photosynthesis, chlorophyll in plants captures the sun's energy by converting carbon dioxide from the air and water from the ground into carbohydrates-complex compounds composed of carbon, hydrogen, and oxygen. When these carbohydrates are burned, they turn back into carbon dioxide and water and release the energy they captured from the sun. In this way, biomass functions as a sort of natural battery for storing solar energy. As long as biomass is produced sustainably-meeting current needs without diminishing resources or the land's capacity to re-grow biomass and recapture carbon-the battery will last indefinitely and provide sources of low-carbon energy.
VII. METHODOLOGY 1. We will collect the sample data (requirement of a power) of any particular city or the village. 2. Compute the total cost occurred if we generate the power by using solar, wind or biomass individually in Matlab environment. 3. Then compute the total cost occurred if we generate the power by making the hybrid model of solar, wind or biomass collectively. 4. Carry out the analysis whether it is profitable to make the hybrid model or not.