Preface
Bioenergy has a wide range of applications. It is renewable and eco-friendly. This is a research work on how bioenergy can lead to sustainable energy management. Educational information on types of bioenergy, the resources and processes involved are discussed. Highlights have been done on the benefits of increasing biopower plants. Emphasis is made on improvement of bioenergy through proper waste management system. This project also spreads awareness on Innovations being done in this vast field of bioenergy. The aim of this project is to shift from usage of exhaustible resources to eco-friendly and renewable resources. Bioenergy is one of the fastest growing fields with great potential and energy and hence can be used for a sustainable future.

Key Points
 

§ Bioenergy is a renewable energy obtained from organic materials. 'Organic' refers to living organisms (plants and animals) and materials obtained from them are known as organic materials.

§ Human population is increasing and so is the municipal waste and agricultural waste. Most of the waste is lost to land filling which leads to land degradation. The mixing of organic and dry waste in the dumps also leads to increase in toxicity. With the correct waste management and Segregation this large amount of waste can be used to produce bioenergy. Better waste management system and increase in bio-power plants can help in this field.

§ Bioenergy can be obtained in the form of biomass, biofuel, biogas etc. This energy can be used in transportation, electricity and power generation. It can be used in both small scale as well as in big projects. Bioenergy can be the key energy resource for a global sustainable environment.

§ Bioenergy has various utilization and advantages. Biofuel is the most important fuel worldwide after coal, oil and natural gas. Innovation in this area is fast growing and can lead to a revolution in energy consumption. Giving the correct attention to its development it could be a far advantageous resource.

§ Bioenergy production is an opportunity to deliver a number of social, environmental, and economic benefits in addition to the climate and energy goals. Bioenergy provides good opportunities for agricultural markets and has the capacity to promote sustainable development in rural communities.

 

Introduction
Bioenergy, as the name suggests is the energy derived from organic matter/ bio-organisms (plants and animals). This clean and renewable energy is produced by burning or processing biomass and its derivatives. Plants (primary producers) absorb the sun’s light energy and convert it into chemical energy through the process of photosynthesis. This energy is transmitted along the food chain following the 10% law. The energy is stored in organisms in the form of biomass. It doesn’t add extra co2 in the atmosphere as it gives out the same amount of carbon which was used to process it. It enables the re-use of carbon from biomass. The organic matter which is used to produce bio energy is known as feedstock. It could be Crop wastes, forest residues, purpose-grown grasses, microalgae, urban waste and Food waste. With increase in population, food demand, industry and technology there is an increase in waste produced as well. This waste can be used to generate bioenergy. Many countries have adopted the use of bioenergy to meet their energy demands. Proper waste management system can play a vital role in bioenergy system. If organic waste is properly segregated from urban areas and industries and utilized to generating bioenergy instead of dumping them all, then it would lead to more bioenergy and less land degradation. Bioenergy is used to generate electricity, heat, transportation fuel and bio-products. If used in a sustainable way it could bring about a revolution in the energy management and lead to a sustainable future.

Sources of bioenergy
The source of bioenergy/ biomass comes from agricultural crops, animal and plant wastes, algae, wood and organic residential/ industrial waste and municipal waste. The type of biomass will determine the type and amount of bioenergy that can be produced and the technology that can be used to produce it For example, rich carbohydrate agricultural crops can be used as a biofuel (ethanol, biodiesel), alternatively wet/organic waste can be used to produce biogas through anaerobic digestion, which can be combusted to generate electricity or improved to a transport fuel. 

 

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Varieties in bio-mass/ bioenergy
 

Biofuel
Ethanol is made by the fermentation of biomass that is high in carbohydrates, such as sugar cane, wheat, or corn. Ethanol has become a popular substitute for wood in residential fireplaces. When it is burned, it gives off heat in the form of flames, and water vapor instead of smoke. Biodiesel is made from combining ethanol with animal fat, recycled cooking fat, or vegetable oil. Biofuels do not operate as efficiently as gasoline. They can be blended with gasoline to give efficient power to vehicles and machinery.

Biochar
Biochar is produced during pyrolysis. When biomass is charred, it stores its carbon content and when added to the soil, it continues to absorb carbon and form large underground stores of sequestered carbon that can lead to negative carbon emissions and healthier soil. Biochar enriches the soil and being porous it absorbs and retains water and nutrients. 

[Biochar is used in Brazil’s Amazon rain forest in a process called slash-and-char. Slash-and-char agriculture replaces slash-and-burn , which temporarily increases the soil nutrients but causes it to lose 97% of its carbon content. During slash-and-char, the charred plants (biochar) are returned to the soil, and the soil retains 50% of its carbon. This enhances the soil and leads to significantly higher plant growth.] {National Geographic Society,2011}

Black Liquor
During the production of paper, a high-energy, toxic substance called black liquor is produced. This black liquor from paper mills was considered as a waste product and dumped into nearby water sources. However, black liquor was found to retain more than 50% of the wood’s biomass energy. With the invention of the recovery boiler the black liquor could be recycled and used to generate energy to power the paper mill.

Hydrogen Fuel Cells
Hydrogen is rich in biomass, which can be chemically extracted and used to generate power. Hydrogen fuel cells may hold even more potential as an alternative energy source for vehicles. The U.S. Department of Energy estimates that biomass has the potential to produce 40 million tons of hydrogen per year. This would be enough to fuel 150 million vehicles. [National Geographic Society,2011]. Hydrogen fuel cells are used to power buses, boats, and submarines, and are currently being tested on airplanes and other vehicles. However, there is a dispute as to whether this technology will become sustainable or economically possible.

Algal Fuel
Algae is a unique organism that has enormous potential as a source of biomass energy. Algae can produce energy through photosynthesis at a much quicker rate than any other bio-fuel feedstock, up to 30 times faster than food crops. Algae can be grown in ocean water, so it does not deplete freshwater resources. It also does not require soil, and therefore does not reduce arable land that could potentially grow food crops. Although algae release carbon dioxide when it is burned, it can be farmed and replenished as a living organism. As it is replenished, it releases oxygen, and absorbs pollutants and carbon emissions. Algae take up much less space than other bio-fuel crops. Algae contain oils that can be converted to a bio-fuel.

 

Processes

Biomass can be used directly by thermal conversion to produce bioenergy or it can also be processed into fuel and used for transportation. Biogas produced can be used to generate electricity. Before biomass can be burned, it must be dried. This chemical process is called torrefaction . During torrefaction, biomass is heated to about 390° to 610° Fahrenheit. The biomass gets dried out so completely that it loses the ability to absorb moisture.. It loses about 20% of its original mass, but retains 90% of its energy. The torrefied biomass is then compressed into briquette s. Biomass briquettes are very hydrophobic , this makes it possible to store them in moist areas. The briquettes have high energy density and are easy to burn during direct or co-firing. Different processes are used to generate energy from the biomass- through direct firing, co-firing, pyrolysis, gasification, and anaerobic decomposition.

Direct Firing and Co-Firing
These briquettes are burned directly and the steam produced during the firing process is used to power a turbine , which turns a generator and produces electricity. Biomass can also be co-fired, or burned with a fossil fuel.

Pyrolysis
Pyrolysis is a correlated method of heating biomass. During pyrolysis, biomass is heated to 390° to 570° F in the absence of oxygen. This keeps it from combusting and causes the biomass to be chemically altered. During pyrolysis a dark liquid called pyrolysis oil , a synthetic gas called syngas and a solid residue called biochar is produced. All of these components can be used for energy generation.

Gasification
Biomass can be directly converted to energy through gasification. During the process of gasification, a biomass feedstock (usually MSW) is heated to more than 1,300° F with a controlled amount of oxygen. The molecules break down, and produce syngas and slag. 

Syngas is a combination of hydrogen and carbon monoxide. During gasification, syngas is cleaned of sulfur, particulates, mercury, and other pollutants. The clean syngas can be combusted for heat or electricity, or processed into transportation biofuels, chemicals, and fertilizer s. Slag forms as a glassy, molten liquid. It can be used to make shingles, cement, or asphalt. [National Geographic Society,2011]

Anaerobic Decomposition
Anaerobic decomposition is the process where microorganisms, usually bacteria , break down material in the absence of oxygen. Anaerobic decomposition is an important process in landfill s, where biomass is crushed and compressed, creating an anaerobic (or oxygen-poor) environment. In an anaerobic environment, biomass decays and produces methane, which is a valuable energy source.

Bio-Power Plants in India
Bio-power plants use biomass and their derivatives to generate bioenergy. It is an eco-friendly way to shift our dependency on fossil fuels to more natural methods. Bioenergy can easily be generated both locally and on a broad scale. Every village produces agricultural waste, food waste, plants and animal residue and other organic waste. But not all villages have a power-plant or access to electricity. Both can be achieved together. Bioenergy could be the answer. This clean energy is environmentally friendly and has a realistic potential.

The current availability of biomass in India is estimated at about 500 million metric tonnes per year. Studies sponsored by the Ministry of New and Renewable energy has estimated surplus biomass availability at about 120-150 million metric tonnes per annum covering agricultural and forestry residues corresponding to a potential of about 18,000 MW . This apart, about 7000 MW additional power could be generated through bagasse based cogeneration in the country’s 550 Sugar mills, if these sugar mills were to adopt technically and economically optimal levels of cogeneration for extracting power from the bagasse produced by them.

There is ample potential of setting up biogas plants considering the livestock population of 512.06 million, which includes about 300 million (299.98 million) total population of bovines (comprising of cattle, buffalo, mithun and yak). The livestock sector contributes about significantly to India’s GDP and will continue to increase. The dissemination of biogas technology is a boon for Indian farmers with its direct and collateral benefits.

Source: [Ministry of new and renewable energy, Government of India, 27-10-2020]

Case study on the impact of existing bio power plants- Based on the data reported and evaluation done through third party study (initiated by ministry of new and renewable energy of  government of India), the overall impact and implementation is seen to be positive. The figures given below is the result of a case study of 45 Biogas plants and the extrapolated for 163 projects.
 

Total No. of Plants: 163
Energy Cost Savings (In Rs. Lakhs): 787
Total CO2 Savings (In Tons): 9587
o-manure Production (In Tons): 32582
Employment (Man-days): 63438
ct Employment (Man-days) 56894

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[Source: Government of India]

The above studies show the potential of bio power plants. It resulted positively in reducing carbon emission, provided our energy requirements and also increased employment opportunities. More power plants could lead to more development in energy management and reduce our reliance in fossil fuels and coal.

 

Waste Management and Bioenergy Relations

Waste management (or waste disposal ) includes the activities and actions required to manage waste from its inception to its final disposal. This includes the collection, transportation, treatment and disposal of waste, together with monitoring and regulation of the waste management process. Different waste requires different methods of treatment and disposal. That is why waste segregation and sorting is important. This helps reduce waste and recycling of waste.

However, the waste management system is unable to function to its fullest. The main reason is poor waste sorting. Dry and wet waste is not being sorted efficiently. Dry and wet waste being dumped together releases greenhouse gases, increases total amount of waste and reduces the efficiency of waste to be recycled or reused. Most of the waste is dumped as landfills or into the ocean bodies. This is leading to land degradation and water pollution.

With increase in population there is an increase in municipal, manure and organic waste. Along with it there is an increase in agricultural production so therefore an increase in crop residue. With proper waste management and sorting a large amount of organic waste can be separated from the total waste. This waste can be used to generate bioenergy. Of all the total organic waste 50% can be dumped into land and water for their replenishment and 50% can be to contribute towards our energy demand. Farmers burn most of their agricultural residue openly whereas they can burn it in a power plant to generate bioenergy to serve their local electricity and fuel production.

Organic waste and sewage waste of towns and municipalities can also be used in power-plants to
generate bioenergy. According to the Ministry of new and renewable energy it is estimated that there exists a potential of about 1460 MW from MSW and 226 MW from sewage.

                                              India - Potential of Energy Recovery from Urban and Industrial Waste