The bottlenecks that hindered the progress of waste to energy and biomass being cleared, the two ‘underdogs’ of the RE community are now paving the way for a sustainable RE world.
The possibility to use residues and waste as a biomass feedstock enables the production of huge quantities of energy and environmental benefits all over the world. Investment in bioenergy is strategic in order to achieve a sustainable global energy policy.
Waste: No longer waste
Our country has a massive potential for waste to energy. For a stat, our metros, all put together, produce close to 60 MT of waste per day. Even if the rest of the urban and rural areas contribute to 40 MT per day, we dwell with a 100 MT per day of waste which gets land filled and erodes our soil.
Soil erosion has a direct impact on agriculture which has been our nations prime sector from ages. Besides, it will pollute and expose us to decay and will very soon become a pandemic for the society. It’s hence imperative for us to gear up and protect ourselves with lucrative and environmental waste to energy projects. Renewable energy combined with waste to energy has a potential of addressing at least 30 per cent of the country’s energy demand.
Technologies put into use
Various technologies/processes are available for the generation of energy from waste, primarily depending on the properties of the waste handled. Few technologies commercially tried & tested are:
a. Bio-methanation: Anaerobic digestion of bio degradable organic waste in an enclosed space under controlled conditions of temperature, moisture, pH, etc., using bacteria which produces biogas and bio-fertilizer.
b. Incineration: Combustion of waste at a very high temperature in the presence of oxygen, resulting in the production of ash, flue gas and heat.
c. Composting: Controlled aerobic process of biologically digesting the waste, so it may be recycled for other processes such as for plant nutrient, stabilisation of soil in remediation process or for increasing soil fertility.
d. Refuse derived fuel: Rrefers to a high calorific non–recyclable combustible fraction of processed waste which is used either as fuel for steam and electricity generation or as alternate fuel in industrial furnace & boilers.
Ramping up the need for biomass generation
India is the 7th largest country in the world with an area spanning 328 million hectares and amply bestowed with renewable sources of energy. Among the renewable energy sources, biomass plays a vital role especially in rural areas, as it constitutes the major energy source to majority of households in India.
India produces about 450-500 million tonnes of biomass per year. Biomass contributes to 32 per cent of all the primary energy use in the country at present. The country has over 5000 MW biomass based power plants, comprising 4000 MW grid connected and 1000 MW off grid power plant. Out of the total grid connected capacity, major share comes from Bagasse cogeneration and around 115 MW is from waste to energy power plants.
Considering the present status of biomass based power generation and thermal application, it is expected that only about 30 – 35 million tonnes of surplus biomass is being used annually for the existing and ongoing biomass projects. However, a lot needs to be done on the compliance and policies to benefit the stakeholders in the supply chain.
The current share of biofuels in total fuel consumption is extremely low and is confined mainly to 5 per cent blending of ethanol in gasoline, which the government has made mandatory in 10 states. Currently, biodiesel is not sold on the Indian fuel market, but the government plans to meet 20 per cent of the country’s diesel requirements by 2020 using biodiesel. This shall certainly accelerate the biomass industry in the near future.
Biomass sector: Ready for take-off!
The biomass sector has already taken off but a massive revival is required. This can happen by encouraging farmers to grow such crops and on the business front, make it viable for the farmers as well as the biomass briquettes / pallets, biogas industries. Right now, none of the parties yield any profit which is very discouraging. Banks also should give attractive loans for cultivating new crops.
The electricity generation could be cheaper than coal if biomass could be sourced economically but some established biomass power plants tend to misuse the limit of coal use provided to them (generally 10-15 per cent of biomass use) to keep it operational in lean period of biomass supply. They are not able to run power plants solely on biomass; economically it can be attributed to:
• The cost of biomass increases rapidly after the commissioning of power projects and therefore, the government tariff policy needs an annual revision
• Lack of mechanisation in the Indian agriculture sector
• Defragmented land holdings
• Most of the farmer’s land are small or marginal
Though the current Central Government has introduced very good initiatives such as Swatch Bharath, Gobhar Dhan, Smart Cities etc., any impressive movements/initiatives at the state level has been minimal. Hence, we need to be more aggressive in implementation of these initiatives.
Technological advancements to look out for
Few new technological advancements are as mentioned below:
• Pyrolysis with an IC engine: Various processes exist for pyrolysis of wood to produce bio-oil, and after suitable treatment, this can be burnt in a compression-ignition engine.
• Organic rankine cycle turbines: This is the same engine cycle as used by conventional steam turbines but instead of water, a closed system organic fluid is used as the working fluid.
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