could be compressed as bales or briquettes in the field, rendering transport to the
site of use a viable option. Nevertheless, the logistics of a supply chain is more
complicated in the case of straw. Although five different energy conversion technologies seem to be applicable for rice straw in principle, only combustion technology is currently commercialized and the other technologies are at different stages
of development. As a general rule for energy use, each step in the chain consumes a
certain amount of energy and thus reduces the net energy supplied at the final stage.
5 Thermal Combustion
Rice straw can either be used alone or mixed with other biomass materials (the latter
is called co-firing or co-combustion) in direct combustion. In this technology,
combustion boilers are used in combination with steam turbines to produce electricity and heat. In thermal combustion, air is injected into the combustion chamber
to ensure that the biomass is completely burned in the combustion chamber.
Fluidized bed technology is one of the direct combustion techniques in which solid
fuel is burned in suspension by forced air supplied into the combustion chamber to
achieve complete combustion. A proper air-to-fuel ratio is maintained and, in the
absence of a sufficient air supply, boiler operation encounters various problems.
In straw combustion at high temperatures, potassium is transformed and combines with other alkali earth materials such as calcium. This in turn reacts with
silicates, leading to the formation of tightly sintered structures on the grates and at
the furnace wall. Alkali earths are also important in the formation of slags and
deposits. This means that fuels with lower alkali content are less problematic when
fired in a boiler (Jenkins et al. 1998). The by-products are fly ash and bottom ash,
which have an economic value and could be used in cement and/or brick manufacturing, construction of roads and embankments, etc.
The National Biomass Assessment Project of Ministry of New and Renewable
Energy, Government of India, conducted a biomass study in which 29 tehsil were
surveyed from 1995 to 2001. A total of 36 Talukas were included from different
districts. The power generating potential was estimated at 342 MW (see details in
Table 2). Following these developments, PEDA facilitated setting up of a 6 MW
biomass power project at village Gulabewala in district Muktsar. This was undertaken as a joint project with M/s Malwa Power Pvt. Ltd., at a cost of Rs. 21.50
crore. The project was completed and commissioned in May 2005 and is operating
satisfactorily.
Encouraged by the success of Gullabewala, PEDA is collaborating with the
private sector for the establishment of power projects based on agricultural residues.
A total of 20 projects with a total installed capacity of 320 MW have been allotted on
BOO basis to private developers. These projects are being set up by the private
developers with the state-of-the-art technologies such as biomethanation, combustion, etc. The plants are designed to receive mixed waste such as paddy straw, cotton
stalks, and other agro residues available in the state. Two projects of 8 and 14.5 MW
514
P. Kumar
site of use a viable option. Nevertheless, the logistics of a supply chain is more
complicated in the case of straw. Although five different energy conversion technologies seem to be applicable for rice straw in principle, only combustion technology is currently commercialized and the other technologies are at different stages
of development. As a general rule for energy use, each step in the chain consumes a
certain amount of energy and thus reduces the net energy supplied at the final stage.
5 Thermal Combustion
Rice straw can either be used alone or mixed with other biomass materials (the latter
is called co-firing or co-combustion) in direct combustion. In this technology,
combustion boilers are used in combination with steam turbines to produce electricity and heat. In thermal combustion, air is injected into the combustion chamber
to ensure that the biomass is completely burned in the combustion chamber.
Fluidized bed technology is one of the direct combustion techniques in which solid
fuel is burned in suspension by forced air supplied into the combustion chamber to
achieve complete combustion. A proper air-to-fuel ratio is maintained and, in the
absence of a sufficient air supply, boiler operation encounters various problems.
In straw combustion at high temperatures, potassium is transformed and combines with other alkali earth materials such as calcium. This in turn reacts with
silicates, leading to the formation of tightly sintered structures on the grates and at
the furnace wall. Alkali earths are also important in the formation of slags and
deposits. This means that fuels with lower alkali content are less problematic when
fired in a boiler (Jenkins et al. 1998). The by-products are fly ash and bottom ash,
which have an economic value and could be used in cement and/or brick manufacturing, construction of roads and embankments, etc.
The National Biomass Assessment Project of Ministry of New and Renewable
Energy, Government of India, conducted a biomass study in which 29 tehsil were
surveyed from 1995 to 2001. A total of 36 Talukas were included from different
districts. The power generating potential was estimated at 342 MW (see details in
Table 2). Following these developments, PEDA facilitated setting up of a 6 MW
biomass power project at village Gulabewala in district Muktsar. This was undertaken as a joint project with M/s Malwa Power Pvt. Ltd., at a cost of Rs. 21.50
crore. The project was completed and commissioned in May 2005 and is operating
satisfactorily.
Encouraged by the success of Gullabewala, PEDA is collaborating with the
private sector for the establishment of power projects based on agricultural residues.
A total of 20 projects with a total installed capacity of 320 MW have been allotted on
BOO basis to private developers. These projects are being set up by the private
developers with the state-of-the-art technologies such as biomethanation, combustion, etc. The plants are designed to receive mixed waste such as paddy straw, cotton
stalks, and other agro residues available in the state. Two projects of 8 and 14.5 MW
514
P. Kumar