The down-stream sugar industry can produce at-least 30+ products and chemicals including some pharmaceutical ingredients.This has been widely known and has been utilized in many countries.The actual feasibility of individual projects in countries depends on product supply, demand,trade, taxation and cost and profitability.The energy potential of sugar industry has,however,been appreciated and recognized more widely only recently.There are three different options and not mutually exclusive to extract energy from sugar industry waste , namely Bagasse/biomass , Ethanol from Molasses and Bio-gas out of waste water digestion.
Bagasse is burnt to produce energy even today in low efficiency boilers.In the bygone times of low oil prices, Bagasse was almost a liability and a mere disposal issue.Low efficiency boilers adequately consumed bagasse for the self requirements of the sugar mills.New technology with almost twice more efficiency(high temp and pressure boilers and steam turbines) and higher energy prices has generated interest and rationale foe replacing the existing low efficiency equipment by higher efficiency equipment , and sell the surplus to the Grid.Electric companies are also more geared today to buy electricity from these resources , technically,procedurally and financially.Several projects are in the pipeline after successful negotiations with NEPRA. There are ,however, some genuine problems and issues faced by implementation of such projects.Except for Brazil,perhaps the largest sugar producing country,the full bagasse potential has not been utilized even in India with a longer history and scope and size of sugar industry and Bagasse utilization.
The major problem is the limited season of sugar cane availability.Sugar mills in Pakistan have a crushing season of only four months.Storage could probably be done for another two months requirement.In other places,sugar season is longer but usually not more than six months.Thus the plant and facilities,very expensive ones, are potentially available for six to eight months.Apart from poor utilization,where should the customer go for the remaining months.Although this is not a unique problem,hydro power also suffers from the same difficulty of seasonality.However no fuel cost in case of hydro power is a major redeeming feature.
One option mostly practiced in India is,where ever there are comparatively longer sugar crushing seasons,keep the plant unutilised in off season and utilize it in must -run mode in the season, trying to get an yearly load factor/utilization of 60% or so.Burning coal is avoided due to environmental costs and other reasons such as loan conditions and CDM income and provisions.
The other option is to burn coal, which has futher two options.In one option usually followed in developing countries including India as well and the same has been proposed for recently approved projects in Pakistan.The bagasse stoker boilers are generally low efficiency as compared to a typical coal boiler:25-28% for stoker and38% for coal. This means that burning coal in bagasse boilers is about 33% less efficient,which is a big loss but averages out by higher efficiency increase of bagasse boilers.This is probably not a very good solution but often found feasible.Coals pollution and traffic congestion that may be generated by massive coal traffic on the roads would be additional problems to cope with.The other option mostly adopted in the developed countries with coal power plants is co-firing of biomass including bagasse in conventional coal boilers, but in a manageable ratio of 10-15%.And this is done without loss of efficiency.We do not have coal power plants and thus cannot benefit from it in the near future.
Perhaps the best option is to utilise other biomass which may be potentially available in sugar off-season.Agricultural residue,rice husk , corn-cob and shrubs etc.The solution should be implemented where ever feasible.No compromise on efficiency , no coal pollution or traffic congestion. Besides the projects would remain eligible for CDM revenues and other concessional green financing.Some of our bright entrepreneurs have seen the light and are considering to move in this direction.