After analysing some intriguing and complex systems like solar, wind and nuclear energy in previous articles of this series, we now move on to something more lively! Carbon – one of the most abundant elements in the world, is nothing short of a magic!
So, what’s magical with the mundane carbon? With combination with Oxygen, Hydrogen and in cahoots with Chlorine, fluorine, sulfur and others, Carbon forms the thread and web of life. From bacteria to blue whale, from charcoal to diamond, from CFC’s to GHG’s, Carbon is ubiquitous but their presence is forgotten just like India’s non-cricket sport heroes. Bioenergy – the energy derived from organic/biodegradable matter can serve the dual purpose of achieving carbon neutrality (perhaps, carbon negative emissions too) and tackling the waste debris engulfing our nation.
Bio-energy in India
In the total installed capacity of around 343.7 GW in India, Bioenergy accounts for just 8.8 GW making up just around 2.5%. This number is too low for a nation with an agrarian background receiving bright sunshine throughout the year and copious water. Out of 8.8GW, the cogeneration plants take up 8.7 GW. Cogeneration is a process where there is production of both heat and electricity from agro-based residues-particularly sugarcane bagasse. Baggasse is used as a fuel to produce high pressure steam. Based on the necessity of the industry, either the steam is used to generate electricity first and then used for heating or the steam is first used for heating application and the residual heat is used in electricity generation.
Cogeneration has been a very successful technology for industries in meeting their own energy demand in an economical and eco-friendly way, but it does suffer from issues, the main one being the non-availability of fuel through-out the year. The feedstock – sugarcane baggasse is just available for a short period of time in a year and the co-gen facility has to lay idle till it receives feedstock or it has to import coal, produce and export electricity.
The other type of bio-based power is the waste-to-energy plant. A look into the data on municipal solid waste management will be astounding. Tamil Nadu one of the top seven developed states in India itself generates 14,600 Tonnes per day of Municipal Solid waste. The percentage of bio-degradable matter in this waste is about around 45-55%. Just imagine the magnitude of waste generated from hostels, marriage halls, large institutions, restaurants apart from dry leaves, agricultural residue, and waste from poultry & animal husbandry. If even 80% of the total degradable waste can be collected, then it amounts to 5840 tonnes of biodegradable wastes. If not treated properly, it can have a huge environmental cost. When dumped in wastelands, the waste decomposes and poses a public health hazard. When they are in water bodies, it leads to depletion of Dissolved Oxygen (necessary for respiration of aquatic species) which is consumed by the bacteria in order to decompose the waste. So, it is of paramount importance that we deal with biodegradable waste.
Even if 80% of the total degradable waste can be collected, then it amounts to 5840 tonnes of biodegradable wastes.
The now-defunct biogas plants in the villages are the best solution to this menace. All type of biodegradable municipal solid waste – from poultry wastes to vegetable market wastes can be decomposed to get biogas (also known as gobar gas when produced using cattle dung) in one hand and rich organic manure in the other! Biogas can be used as a clean burning fuel for domestic purposes and as an alternative fuel to the high polluting diesel & petrol. Refined & processed biogas will be absent from Particulate matter, Nitrogen and sulfur. The organic manure from anaerobic decomposition is free from pests and pathogens as the reaction is exothermic in biogas plants and is also superior to aerobic compost in terms of nutrient content and can be effectively used as a FARM YARD MANURE (FYM). The biogas technology is a proven old technology with many models such as Nisargruna, KVIC, Deenabandhu models as some examples. The central government has taken cognizance of this fact and the finance minister Shri. Arun Jaitley came up with GOBAR (Galvanising Organic Bio Agro Resources-DHAN Scheme) in the budget which was highlighted in the Prime Minister’s Mann-ki-baat session to give impetus to biogas plants. Biogas is an exemplary role model to showcase Circular Economy – how waste can be used in myriad ways to achieve sustainability.
In Indian cities, aerobic composting is currently being employed for the treatment of biodegradable waste. Being a traditional method, there is a chance of mixing of hazardous waste in the bio-waste which is to be composted. Further, there is no incentive/gain in aerobic composting, whereas in biogas plants, we get biogas as fuel for cooking & electricity along with FYM. It needs plenty of water which can be procured from wastewater treatment plants. Bio-methanation plants were used in Coimbatore but time and again, there was no maintenance which rendered it useless.
Bio-toilets in trains are an excellent use of bacteria to treat the fecal matter. Indian Railways carried nearly 8116 million passengers in the year 2016-17. To treat the biodegradable wastes from all trains is itself a monumental task. Bio-toilets use the same technology as biogas plants to degrade waste where anaerobic bacteria is employed resulting in production of CO2 and Methane which is left to escape. In line with swachh bharat, bio-toilets are being fitted in all trains to improve sanitation. We can expect all the tracks and train toilets to be neat hereafter!
To sum up, bio-energy especially in the arena of waste management holds the key for the future. If we could harness it, we can hit the bull’s eye in the race to sustainability.
This article was originally published in the agricultural and environmental e-Magazine, “The Agraria“.