Energy Techonologies - Bagasse-based Cogeneration

Introduction

In simple terms, cogeneration is the process of using a single fuel to produce more than one form of energy in sequence. Cogeneration of steam and electricity can significantly increase the overall efficiencies of fuel utilization in process industries. A minimum condition for cogeneration is the simultaneous requirement of heat and electricity in a favourable ratio, which is well fulfilled in the sugar industry. The thermodynamics of electricity production necessitates the rejection of a large quantity of heat to a lower temperature sink. In normal electricity generation plants, this heat rejection takes place in condensers where up to 70% of heat in steam is rejected to the atmosphere. In cogeneration mode, however, the heat is not wasted and is instead used to meet process-heating requirement. The overall efficiency of fuel utilization can thus be increased to 60% or even higher in some cases. Capacity of cogeneration projects can range from a few kilowatts to several megawatts of electricity generation a long with simultaneous production of heat ranging from less than a hundred kW th (kilowatts thermal) to many MW th (megawatts thermal).

Potential

The potential for cogeneration projects is estimated at 3500 MW of additional power generation from the country's existing functional sugar mills.

Achievements

India, today, is perhaps the world leader in the implementation of modern cogeneration projects in sugar mills. The achievements merit attention not only because of the additional grid-connected power generation capacity but also because of the large number of sugar mills, which have implemented these projects. This is noteworthy because of the diverse nature of operating conditions across these mills. An additional power generation capacity of 447 MW has been commissioned in 58 sugar mills as of March 2005. A further capacity addition of about 313 MW in 34 sugar mills is reported to be under implementation. A state-wise distribution of the commissioned and 'under implementation' capacity is given in Table

State-wise distribution of commissioned and 'under implementation' cogeneration capacity, as on 31 March 2005.

Technology and equipment

The technology for bagasse-based cogeneration has become fairly well established in the country. The main equipment required for these projects comprise high-pressure bagasse-fired boilers, steam turbines, and grid-inter-phasing system. All these equipment are manufactured indigenously. An extremely competent and experienced group of technical professionals capable of providing comprehensive project and operational services has also been developed in the country to support bagasse-based cogeneration projects.

Costs

The capital costs of installed bagassed-based cogeneration projects in sugar mills are known to range between Rs 3 crores/MW and Rs 4 crores/MW. It has been seen that for a typical sugar mill having an average crushing season of 160 days, investments for additional power generation through cogeneration will turn out to be beneficial in the long term.

Financial Incentives

The present levels of interest subsidy offered by the MNES for various categories of bagasse-based cogeneration projects are detailed in Table

Interest subsidy for different categories of bagasse-based cogeneration projects

However, these are subject to change from time to time and the latest information on the scheme of incentives can be obtained from the MNES website: www.mnes.nic.in

Main Application: Energy

Contact:

Ministry of Non-Conventonal Energy Sources,
Govt. of India
Block-14, CGO Complex, Lodi Road
New Delhi – 110 003
Tel: 91 11 2436 0707/ 2436 0404
Fax: 91 11 2436 1298

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