Sugarcane - an Energy crop

Dr.K.Rajendran Ph.D

Energy Content of Sugar-cane

Sugarcane is an Energy rich Crop and one Ton of Cane contains about 4500 MJ energy in which about 1800 MJ is lost in the boiler flue gas and about 750 MJ heat energy is dissipated to atmosphere through the cooling tower / spray pond.

Energy of one ton of cane approximately equivalent to 1 barrel of oil

One ton of bagasse at 50% moisture produces about 2.15 tons of steam, and 5.8 tons of bagasse (50% moisture) equals 1 ton of oil.

Energy products of Sugar cane

Power/electricityAlcohol Ethanol

Individuals, Society, Organization, States, Nations and entire world aim for Sustainable development. Sustainable development benefits entire community in all aspects viz. social, economic, technological, and environmental.

Present situation in India

Indian Sugar Industry in India characterized by High cost of production and 80% of the cost production goes towards raw material aloneOld ,out dated and obsolete Technologies,Small factories i.e. less than 2500 TCD Relatively concentrating on Sugar onlyHence the need of the hour….Sugar production alone is not profitable.Electricity generation, production of Alcohol and Ethanol are important to ensure sustainability and financial viability and survival in the competitive environment.

Why diversification is needed in sugar industry?Integrated production of sugar, ethanol

and energy as electricity offers viable potential.

Demand for Fuel ethanol is rapidly growing in India.

Import substitution for Petrol/Crude and conservation of Foreign exchange

Cogeneration, the combined generation of steam and electricity, is an efficient and cost-effective means to save energy and reduce pollution. Many studies around the world have identified sugar mill cogeneration as an attractive low-cost option to place additional generating capacity on the grid.

Several studies revealed that the sugar industry as a prime candidate for supplying low-cost, nonconventional power via cogeneration and the advantages of sugar mill cogeneration include relatively low capital cost requirements and the use of a renewable, indigenous waste as a “non-polluting” fuel.( Smouse et al.)

What is cogen?Cogeneration means simultaneous production of heat and

power, with a view to the practical application of both products. Heat is main product, electricity by-product or alternate, uses heat that is lost otherwise.

Cogeneration is not new to the cane sugar Industry , but however Cogeneration based on High pressure boilers and extraction condensing or straight condensing machines are definitely new to the industry

All sugar plants are Cogenerating power right from their inception, Cogeneration for surplus power generation has gained momentum in 1993.

Cogeneration scheme should consider the available bagasse, variations in the bagasse availability during season and availability of coal or biomass during off season and process steam requirements in the factory during crushing season.

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Benefits of cogen

Cost of production of power per unit is very cheap.Quick return on investments.Restore ecological imbalance. Reduced use of fossil fuel.Ability to use Bio-Mass and other locally available organic

matters Availability of power during crushing period- between Nov.

to May.economic and timely solution of Power problems in the

country. Reduction CO2 in the environmentConservation of Natural ResourcesLower T&D losses

Cogen principleWhen steam or gas expands through a turbine, nearly 60 to

70% of the input energy escapes with the exhaust steam or gas.

This energy in the exhaust steam or gas is utilized for meeting the process heat requirements.

Such an application, where the electrical power and process heat requirements are met from the fuel, is termed as “Cogeneration”.

Cogeneration is the most efficient way of generating electricity and heat from a given amount of fuel. It saves between 15-40% of energy when compared with the separate production of electricity and heat.

A number of different fuels(multiple fuel) and proven, reliable technologies can be used

It is also known as ‘Combined Heat and Power (CHP)’ and ‘Total Energy System’. Power and Combined Heat and Power (CHP) plays an important role in sustainable development.

BOILER ALTERNATORTURBINE

TO

PROCESS

TO PROCESS

Fuel

Air

TO POWER SUPPLY

CONDENSER

TO COOLING TOWER

COGENERATION PLANT LAYOUT

Feed water

PRDS

Pre requisitesFeed water quality control and Boiler Water Management, An effective bunker system for the storage of bagasse,

moisture in the bagasse controlled to a value of around 50%.,

turbine for the Sugar plant Cogeneration-servicing and spares availability,

Process side steam Economy, design of the electrical systems for the Cogeneration

parallel the cogeneration plant at 110 kV level. Distributed Control System(DCS) skilled Man Power,

Some considerationsThe initial investment of cogeneration projects

may be high but payback period is low( between 3-5 years).

The payback period and profitability of cogeneration schemes depends upon realisation of sales price for electricity.

Environmental concerns, new avenues for non conventional energy sources and increased demand for power are likely to improve market conditions for cogeneration.

Where energy savings in sugar millsConversion from low Pressure to HP Boilers(Saving of

Bagasse by adopting high technology HP Boilers, Reduction of moisture in bagasse 50 to 45% by improving Milling Technique).

Mill House/Crushing section-Reducing moisture percentage in Bagasse, Reduction in consumptions of power per Ton of Cane by installing Variable frequency drives and high efficient auxiliaries.

Evaporator section(Reduction in Process steam consumptions in evaporator and Prime movers by installing Planetary Gear systems Reduction in live steam consumption

Save power inside the factory to export more power to gridElectrical Energy consumption can be reduced by

incorporating various Energy Efficient Equipment like , VFD, Energy Efficient Transmission gears, pumps and motors, etc. and thereby power export can be increased.

Energy efficient gears may be introduced Feeder table, Cane Carrier, Milk of lime stirrers, Crystallizers drives, Molasses and magma pumps, Pug-mills and Magma Mixers, etc to save power consumption in the factory.

Condensers & Cooling System, Energy efficient Pumps and Motors, Juice and Water Flow Meters

1 ton of cane gives 125 units of Power of which 35 units

required for the mills and 90 units of may be exported to Grid.

In addition 1) Sugar (9.5% recovery) : 95 kg2) Molasses ( 4.5%) : 45 kg(10.8 Lit of

Ethanol)3)Press mud ( 3%) : 30 kg(Recovery is considered at 9.50 %)(As per the amended Sugar cane control order, if Ethanol is produced directly

from Juice 60 liter will be obtained)

One ton of Molasses gives

Rectified Spirit : 220 Litres or Ethanol : 210 Litresor ENA ( Extra Natural Alcohol) : 215 Litres

Molasses is one of the important by product of the sugar industry. Molasses, on distillation produces rectified spirit, extra neutral alcohol, denatured spirit, and ethanol.

Alcohol is used in Liquor, pharmaceuticals and chemicals industries.

Ethanol is also a valuable fuel, which is blend with Petrol.

Demand for Alcohol /EthanolDemand for alcohol is increasing every day for

IMFL/

Chemical industries Mandatory for blending with Petrol and frequent

increase of petro products have increased the demand for ethanol

In addition to sugar mills, corn based alcohol/ethanol plants are coming up to meet the increased demand.

Potential is unlimited for alcohol and ethanol in India.

Biofertilisers from canePress mud a byproduct, is sold as such by

some mills to the cane growersSome mills process the press mud and sell it

as enriched pressmud, which can be directly applied in the field.

Some mills process pressmud with cowdung and earthworm and sell as Vermicompost or fertilisers ata higher price from Rs 1500 per MT

Road aheadSugar complexes instead of Sugar millProduction of sugar, biofertiliser, power,

alcohol and ethanol under one roof.Increased financial profitability and self

relianceTaking care of environment along with the

economic development of farmers and march towards sustainable development.