Organic waste to energy: importance and various technologies

Today the demand for energy is constantly increasing across the world due to growing population, technological advancement and economic development. Energy is a vital resource not only for urban development but also for the development of the overall civilization. It has been observed that cities have a significant role in climate change as they use two-thirds of the world’s energy and consequently produce 70% of greenhouse gas (GHG) emissions. This energy is mainly derived from fossil fuels like coal, natural gas and crude oil, which leads to air pollution, greenhouse effect and most importantly, increased carbon footprint. The fact to consider is what will happen when the fossil resources of energy get exhausted? In this context Hariom Chavan writes that “Fossil fuels are going to get exhausted in the next 50 years, so we have to use high quality renewable alternative fuels”1 This is not a simple prediction. Today we need to think in the context of this potential crisis. In the context of this crisis, many sources of renewable energy are being explored like wind energy, solar energy but another resource for green energy is bio-energy which can also be beneficial in the context of our possible crisis.

Introduction to Bioenergy:

Today, to reduce our growing environmental footprint, we can produce green energy by using biomass such as agricultural crops, microalgae or organic waste. Not only this, but we also need to develop this energy as an economically viable and environmentally friendly renewable energy. Biogas is a good source of energy in this regard. Wind, water and solar energy are also some alternative energy sources that help in eliminating these harmful emissions. Biogas is one of the most important energy sources these days as it not only acts as an environmentally friendly energy source but is also useful with high efficiency.

India is the fourth largest petroleum consumer country in the world. Due to its 6 to 8% annual economic growth, it is highly dependent on various petroleum products such as petrol, kerosene and natural gas. Excessive use of biofuels leads to various environmental problems. Such as global warming, snow melting, floods, droughts, etc. Hence, today there are many renewable resources available to meet the increasing demand for energy but biogas is the best option among them. Biogas can be produced from a variety of wastes, such as animal manure, sewage, sewage, solid waste and food scraps.

Biogas not only reduces waste but also provides high quality fertilizer for agriculture in the biogas production process. “The main component of biogas is methane (CH₄), which can be up to 65%.”2 In this sequence, we can also develop biofuel made from algae or microalgae with environmental, economic and social benefits. Microalgal biofuel is considered a third generation biofuel, which is emerging as the energy source of the future. This fuel helps in reducing greenhouse gas emissions. Apart from this, other alternative solutions can also be helpful in solving global environmental problems.

Importance of Bioenergy in Circular Economy Model:

When we talk about the circular economy, we find that it is a sustainable model that attempts to prevent global problems such as depletion of natural resources, degradation of ecosystems, and climate change. That is why the importance of this model has increased in the last few decades because “the demand for natural resources and materials has increased rapidly in the last few decades, increasing the importance of the circular economy model.”3 This model is more beneficial than the traditional economic model because it reduces the use of natural resources and waste in the environment and also reuses it. Three pillars of this circular economy have been accepted. One – reducing waste as much as possible, second, if waste is produced, then reuse it and third, recycling the waste.

Considering the basic principles and characteristics of the circular economy, the European Parliamentary Council Framework states that “the circular economy is defined as an economic system where the value of products, materials and other resources is maintained for as long as possible. Its objective is to increase their efficiency in production and consumption and reduce environmental impact.”4 But when we think more deeply about this model, the form of this model changes and it is said that not producing waste should be the main goal of this circular economy. In this context, the Waste Framework Directive has tried to understand it by dividing it on five levels, in which “prevention of waste has been given priority and sending waste to landfill sites has been considered the last option. Not producing waste is the most powerful way of resource recovery. That is why waste-free production or zero-waste production should be the main goal of the circular economy.”5

Current status of organic waste-to-energy (OWtE) globally:

Organic waste-to-energy (OWtE) is a new approach that combines various waste management activities such as ‘disposal’, ‘recovery’ and ‘recycling’. The EU report says that bioenergy produced from agricultural, forestry and organic waste remains the EU’s leading renewable energy source. According to it, “In 2021, it was about 59% of renewable energy consumption. According to the EU Energy Union’s 2023 Status Report, primary solid biofuels make up the largest share of bioenergy, followed by liquid biofuels, biogas/biomethane and municipal waste as renewables.”6

The EU report considers the contribution of biological energy and says that “the share of biological energy in the total energy balance is very small. For example, in 2016, more than half of the waste generated in northern European countries (Switzerland, Sweden, Finland, Denmark and Norway) was burned for energy production. At the same time, in southern and eastern European countries (Spain, Italy, Poland, Czech Republic) this share did not exceed 15% on average. It was absent in Latvia, Turkey and Serbia.”7 This means that we are not able to use biological resources in energy production as much as we have the potential. That is, we need to take revolutionary steps towards biological energy. This is necessary because agricultural, forest and municipal waste are the main sources of energy. The potential of biological energy sources is enormous.

The main objective of this study is to analyze organic waste to energy (OWtE) technologies to produce renewable energy from organic waste.

Importance of Organic Waste-to-Energy (OWtE):

Population growth and the dreams of becoming developed and the increasing needs have led to a rapid increase in the demand for energy and fossil fuels. This demand has increased not only in developed countries but is also increasing rapidly in developing countries. According to a report, “Global primary energy consumption will reach about 620 exajoules in 2023.”8 This demand is constantly increasing. If we exploit fossil fuels as per the demand, then we will have to face two major challenges. One challenge is standing in front of us right now, that is environmental problems caused by fossil fuels and the other potential challenge is what option will we have when this fossil fuel will get exhausted.

Therefore, we need to reduce the consumption of fossil fuels and turn to other options of energy. In this situation, we have the option of renewable energy. We can reduce our dependence on fossil fuels through renewable energy options. Organic waste-to-energy is a sustainable option among various renewable energy options. For example, solid organic waste is a renewable energy resource, which we can convert into fuel in solid, liquid and gaseous forms and can fulfill various energy needs.

Organic Waste to Energy (OWtE) Technologies:

Today we have a variety of organic waste-to-energy technologies. In fact, through these technologies, organic waste is converted into electricity or heat instead of burning or dumping it in vain. In this context Kalair, A.R writes that “Waste-to-Energy (WtE) technology converts waste into electricity or heat, instead of burning fossil fuels and thus reduces greenhouse gas (GHGs) emissions.”9 It is a green energy option. These technologies of converting organic waste into energy prove beneficial in sustainable development waste management. We can benefit from these technologies. On one hand we can manage waste and on the other hand we can also produce energy from it. Through these technologies municipal waste, agricultural residues, animal waste, food waste and industrial organic waste can be recycled, which makes the production of green energy possible.

Through the following various technologies “agricultural organic waste or biomass can be efficiently converted into bioenergy sources such as bioethanol, biobutanol, biomethane, and biohydrogen. This is possible through biochemical and thermochemical processes.”10 Biochemical processes consume less energy, hence reducing capital and Operating costs also reduce.

Major types of OWtE technologies:

Today we have many technologies for organic waste-to-energy but we will consider only six technologies here.

Aerobic Composting and Vermicomposting:

This technology converts organic waste into manure with the help of microorganisms or earthworms. This technology produces high quality organic manure, which helps in increasing agricultural production. However, the energy production is low.

Anaerobic Digestion: (AD)

This is a special method that breaks down organic waste without oxygen and produces biogas (mainly methane). The methane produced is useful in various purposes such as power generation and can be successfully used as cooking gas. Apart from this, the waste material left can also be used as organic fertilizer.

Biomethanation:

This can produce methane rich gas by fermenting waste. This technology proves beneficial for rural areas and small-sized industries.

Pyrolysis and Gasification:

This technology is beneficial due to its unique properties. Under this, waste can be converted into gas oil or charcoal without pyrolysis or limited pyrolysis at high temperature. This technology produces syn gas or synthetic gas which can be used in power generation.

Incineration and RDF (Refuse-Derived Fuel):

Under this technology, organic waste is burnt at high temperature and energy is produced. In RDF technology, a specific fuel is prepared by modifying dry organic waste. Some problems like air pollution can arise in this process.

Bioethanol and Biodiesel Production:

We can produce bioethanol and biodiesel from organic waste. This technology can become a strong alternative to traditional fossil fuels.

Advantages of OWtE Technologies:

The various technologies mentioned above have various advantages such as we can dispose of organic waste in a scientific way. We can use organic waste in various production systems or for energy production which boosts sustainable development.

If we use organic waste for energy production then it comes to us as a green energy source. When we do this type of energy production then our dependence on fossil fuels continuously decreases which promotes sustainability.

This type of energy production activities from organic waste reduces carbon emissions and contributes to creating a carbon neutral world.

Organic waste can be used to produce not only energy but also various types of products like fertilizers for agriculture, biofuel and biogas which boost the economy in various aspects.

Role of organic CO₂:

CO₂ emissions generated by the decomposition or burning of vegetation are assumed to have zero pollution impact because under normal conditions it can be absorbed under the life cycle. It is possible to re-absorb this CO₂ by growing new plants in place of the burnt or destroyed plants. In contrast, such an assumption is impossible for CO₂ generated from fossil fuels. The carbon dioxide present in fossil fuels is generated by the process of conversion of organic material into fossil oil due to pressure and temperature over geological ages. This process takes place over millions of years and has a long-term environmental impact. Hence, the role of organic CO₂ is important in waste-to-energy technologies. These technologies can reduce greenhouse gas emissions to a great extent.

EU Policies:

In recent times, the EU has implemented various policies and initiatives to convert organic waste into energy. According to CEWEP (Confederation of European Waste-to-Energy Plants), “there are about 500 incinerators in 23 European countries.”11 In this context, Ahmed writes in his article that “In addition, there are more than 4500 bio-treatment waste plants in the EU.”12 whose collective capacity is more than 45 million tons of organic waste per year.

Conclusion:

Needless to say, the need of the hour is to tackle environmental pollution while reducing dependence on fossil fuels. This demand of today is motivating us to search for new sources of energy. In this direction, waste-to-energy (WtE) technologies can become an important part of the sustainable resource recovery process. Our increasing dependence on non-renewable resources today can become a serious challenge in the times to come.

Thus, technologies for producing energy from organic waste are emerging as an alternative energy source today. Biological CO2 sequestration is particularly exemplary for preventing environmental damage. As a result, new strategies are needed to increase the efficiency of obtaining energy from waste and to incorporate it into the principles of circular economy and substitution. There are many successful examples of practical applications of this technology in European countries that clearly demonstrate its economic and environmental benefits. We should take inspiration from these countries.

References:

INTERNATIONAL JOURNAL OF CREATIVE RESEARCH THOUGHTS ( IJ PUBLICATION ), Pravin Hariom Chavhan ; M.P.Yadav , Volume 10 , Issue 5 , May 2022 , Pg :- 24
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