What is Biogas?
The idea of producing flammable gas from decomposing plant matter was brought up by the ancient Persians. The idea culminated to the building of the first sewage plant in 1859 in Bombay, India. The concept was then brought to the U.K. in 1895 when the generated biogas was utilized to light up street lamps. Further advancements in the biogas systems were witnessed in Germany and U.K. at the onset of the 1900s for sewerage treatment purposes. Centralized drainage systems spread across Europe and anaerobic digestion was viewed as a means to minimize the amount of solid waste in the sewage. The resultant gas was sporadically utilized as an energy source to power vehicles.
In the 1930s, farm manure was used to produce methane gas in Bombay. An improved design that used a floating steel gas drum was developed at the start of the 1960s, which became the cornerstone of the government of India’s outreach program to offer villagers a convenient means to cook their foods. In the same year, China rolled out the same initiative, and by 1980, there were more than 5 million biogas plants. The 1980s saw the replacement of the rectangular biogas plant design by the dome shaped design. The biogas program was exported to Nepal, which is today known as Biogas Sector Partnership (BSP).
The skyrocketing prices of oil in the 1980s led many people to embrace biogas. However, the prices of oil dropped later, which translated to a significant drop in electricity bills. This phenomenon reduced the biogas enthusiasm, but few biogas plants managed to survive. The biogas programs in India, China, and Nepal have scaled up steadily over the years. Today, interest in biogas around the world has gathered momentum and more people and setting up biogas plants to produce biogas. India invests more than INR 6 billion each year in the biomass generation sector, producing more than 5000 million units of electricity in the process. The industry also creates annual employment of 10 million man days in remote villages.
By definition, biogas is a kind of biofuel generated through biological breakdown of organic matter such as food scraps, manure, wastewater sludge, and crop residue in the absence of oxygen. This breakdown of organic matter without the presence of oxygen is known as anaerobic digestion. Anaerobic digestion takes place in a large tank commonly known as a digester. Inside this digester, bacteria convert these organic wastes into methane gas, a reliable source of energy.
Biogas is majorly a mix of methane and carbon dioxide. It may also contain traces of siloxanes, hydrogen sulfide, and moisture. The resultant energy in the anaerobic digestion (biogas) can be used directly for cooking by burning it in the presence of oxygen. It can also be converted into electricity by using it to convert water into steam, which turns a turbine connected to a generator. Just like natural gas, biogas can be easily compressed and used to power automobiles. Better still, biogas can be purified and upgraded to the natural gas standards when it’s converted to biofuel known as biomethane. The process of anaerobic digestion leaves behind a nutrient-rich matter called digestate, which is commonly utilized as fertilizer.
Most organic matter begins the process of decomposition when it is exposed to oxygen and sunlight. However, organic matter can also decompose without any oxygen, by the process of anaerobic fermentation. This happens due to the bacteria present in the matter which acts during the absence of oxygen. Landfills see a lot of such decay, especially when the waste material becomes wet and receives little sunlight. As a result, a lot of methane and nitrous oxide is produced and released into the atmosphere. Biogas is the result of this decay, and it is an energy source like no other.
Advantages of Biogas
It’s a renewable energy source
The raw materials used in the production of biogas are renewable. Trees and crops will continually grow, which means manure, food scraps, and crop residue will constantly be available.
Production of biogas happens without oxygen, which technically means there is no form of combustion involved. No combustion means there is zero emission of greenhouse gasses to the atmosphere. However, carbon dioxide is produced in the biological breakdown process (anaerobic digestion), as well as in the course of using the biogas. The difference is the carbon dioxide produced is far less compared to that produced by fossil fuels. In fact, the amount of carbon dioxide produced when using biogas is equal to the amount needed for plants to grow. This, in a way, balances the carbon dioxide in the atmosphere.
The fact that it is produced from renewable sources makes it reliable. Other renewable energy sources like solar and wind depend on the weather patterns or day time factors to continually produce electricity. Biogas production continues regardless of the weather. The biogas production process goes on uninterrupted (24/7).
Reduces the amount of waste going to landfills
We all know that overflowing landfills cause environmental impacts such as foul smells and toxic liquids draining into underground water sources. Instead of disposing of these organic materials to landfills, they can be used to produce biogas.
Requires low capital investment
The technology used to produce biogas is pretty cheap. Biogas plants can be developed right at home using locally sourced materials. The resultant gas can be used directly for cooking and generation of electricity. Biogas can also be compressed to achieve the quality of natural gas and utilized to power automobiles. The raw materials used for the production of biogas such as manure, crop residue, food scraps and wastewater sludge are absolutely free. This makes the cost of biogas production significantly low.
Creates green jobs
Biogas plants have created millions of jobs in most countries, especially in the area of waste collection and biogas generation. For example, in India, the biogas industry creates more than 10 million man days jobs each year in rural areas.
Minimizes overreliance of fossil fuels
Many countries like India and China have invested a lot of money in the biogas sector. This has helped these countries cut back on fossil fuel use. This act has particularly helped China, the world’s top consumer of energy, to cut back on the use of fossil fuel sources of energy like oil, gas, and coal.
Waste collection and management significantly improves in areas with biogas plants. More people get involved in waste collection in order to get a source of income. This leads to overall sanitation and hygiene of the areas.
Produces enriched organic manure
The process of biogas generation leaves behind enriched organic manure (digestate), which is a perfect supplement or replacement of chemical fertilizers.
Saves women and children from daunting household chores
Collecting and carrying firewood on a daily basis is a daunting task. Also, exposure to smoke from the firewood can cause health complications. Biogas provides a great reprieve from these activities. Also, biogas minimizes the time needed for cooking and cleaning of utensils.
Disadvantages of Biogas
Little technology advancements
The systems used in the production of biogas today are not efficient. There are no new technologies yet to simplify the process and make it abundant and low cost. This means large scale production to satisfy a large population is still not possible. Although the biogas plants available today are able to meet some energy needs, most individuals and governments are not willing to heavily invest in the sector. This aspect has led many people to put up biomass systems in their homes, which are short on capacity.
Biogas still contains impurities even after refining and compression. When utilized as fuel to power automobiles, it can corrode your engines and lead to extraordinary maintenance costs.
It can’t work in all locations
Biogas production is only feasible in certain locations where raw materials are in plentiful supply. Rural areas provide the best locations for building biogas plants. However, it’s impractical to built biogas plants in large cities.
Not economically viable
Compared to other biofuels, production of biogas is not attractive economically, especially on a large scale. It’s difficult to beef up the efficiency of biogas plants, which explains why people and most governments are coy about investing in this realm.
Image credit: jan_nijman , demsasiapacificvc
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