The World Bank has published a ‘Biomass Atlas’ of Pakistan which presents the potential for setting up power plants at biomass producing sites such as sugar and rice mills, municipal solid waste landfills and dairy farms.

The atlas also identifies scope for greenfield power plants fed by the residue feedstock of crops.

Bagasse offers the highest potential as fuel for cogeneration plants at the existing sugar. The new high-pressure cogeneration plants at the country’s 84 sugar mills could have a combined power capacity output of 1,844MW based on bagasse of about 17.1m tonnes a year produced by these mills. These potential cogeneration plants could produce a trade surplus of about 4,944GWh per year, if only bagasse is used, or 10,759GWh/year if an additional biomass feedstock of around 12.9m tonnes per year is used as fuel for the cogeneration plants.

Municipal solid waste can also be used for large-scale, grid-connected power plants

Municipal solid waste (MSW) can also be used for large-scale grid-connected power plants. With a total MSW amount of around 27,000 tonnes/day at 12 surveyed landfills, around 360MW of gross power capacity can be generated based on the anaerobic digester-based power generating technology. These potential MSW-based power plants could sell about 2,687GWh/year to the grid.

However, rice husk and cattle manure, with a limited energy potential can be used to set up captive power plants for running rice mills and livestock farms.

The report does not include all the existing MSW landfills, rice mills and livestock farms in the country due to the lack of data. The potential for Greenfield power plants using crop harvesting residues was assessed based on their site suitability indicators, the feedstock sourcing area size, the road network density in the region and the distance to the grid.

The site suitability maps were produced for 21 different combinations of energy conversion technologies and power plant capacities.

The theoretical generation potential of crop residues was estimated at 25.3m tonnes per year with an equivalent energy potential of 222,620 tonnes per year. Bagasse accounts for 66pc of this energy potential, followed by rice husk with 20.3pc, maize cobs with 8.8pc and maize husk with 4.9pc.

The theoretical potential of crop harvesting residues was estimated at around 114m tonnes per year with an equivalent energy potential of 448,990GWh per year. 45.8pc of the total energy potential comes from cotton stalk, 30.8pc from wheat straw, 13.0pc from rice straw, 6.1pc from sugarcane trash, and 4.3pc from maize stalks.

Based on the existing uses of the residues by the farmers, the technical potential of crop harvesting residues was estimated at about 25.1m tonnes per year with an equivalent energy potential of 95,065GWh (342,236 TJ/year).

Rice straw accounts for 30.4pc of this energy potential, followed by wheat straw with 27.3pc, cotton stalk with 26.4pc, sugarcane trash with 12.9pc and maize stalks with 3.0pc. It can be seen from these percentages that large amounts of cotton stalk and wheat straw are being used by farmers in the form of cooking fuel, animal fodder and fertilisers, or sold to industries.

In case the farmers’ willingness to sell their biomass residues is taken into account, the technical potential becomes 280,177 TJ/year. Rice straw and wheat straw then account for a majority of this energy potential with 29.2pc each, followed by cotton stalk with 27pc, sugarcane trash with 11.5pc and maize stalk with 3.2pc.

There is a potential use of MSW for energy generation at the landfills. The industrial survey covered 16 landfills in major cities. However, only 12 landfills provided adequate data for the analysis. The combined amount of municipal solid waste (MSW) collected at these landfills is around 29,000 tonnes per day. However, MSW is being sold out for fertiliser production, and the remaining amount of around 27,000 tonnes a day is currently dumped at the 12 landfills. This amount of MSW could generate around 360MW of gross power capacity in the anaerobic digester-based power plants.

The industrial survey covered large-scale livestock farms with a minimum of 1,000 cattle heads. This led to the survey of five dairy farms. Only three of them provided the required information on their GPS coordinates and the production of livestock manure. The combined manure production of these farms is 100 tonnes/day which could support 0.36MW of gross power capacity for anaerobic digester-based power plants.

Published in Dawn, Business & Finance weekly, August 1st, 2016