Vol 7 No 12 December 1997

The development of rural India is an undisputed need of today. The task of development is very closely linked with the supply of power to these areas. Many of the activities leading to income generation as well as the general upliftment in the facilities available in rural areas need a reliable supply of electric power. It may not be incorrect to state that supply of electric power is almost a prerequisite for the development of a region.

Time has shown that dependence on centralised supply of electricity based on conventional sources of energy has not resulted in any reliable solution of the power problem in rural areas. Instead, the concept of decentralised generation and supply of electric power using locally available renewable energy resources is gaining ground. Till now this has resulted in many demonstration projects for different technologies. However, commercialisation of use of renewable energy is yet to take off.

In view of this, DESI Power installed a commercial plant at Orchha near Jhansi in Madhya Pradesh, which has been operating for more than a year now. This article summarises the experiences in installation and operation of this plant during this period.

At Orchha, TARA has set up a centre called TARAGram for commercial activities using appropriate technology. In this centre, handmade paper and low cost building materials are manufactured by employing the local people. These units have machines, which require electric power. When the centre was started, the grid electricity was not available at the site. Thus, there was a need for a system which could meet the base load requirement of the centre and hence make the proposed economic activity in the centre possible.

A survey of the region showed that two weeds - ipomea and lantana camera - were abundantly available in the region. Ipomea was found to be available over large areas, growing in marshy areas or near water bodies. This weed, which has a substantial woody part, is not used by local population for any purpose. It is not suitable for use as fuelwood since it gives out an obnoxious odour at the time of burning. Lantana, on the other hand, is one of the fuels used locally for cooking.

Both these varieties of biomass were found to be quite suitable for gasification, i.e., a process by which the biomass is converted into producer gas through partial combustion in the presence of controlled supply of oxygen. The producer gas thus generated, is primarily a mixture of carbon monoxide, hydrogen, carbon dioxide and nitrogen. The gas which is combustible, can be used in diesel engines to replace upto 80 percent of the fuel.

Considerable work has been carried out on gasifiers for more than a decade by many groups in the country and there are a few designs available now. One of these is the open-top gasifier developed by Indian Institute of Science (IISc), Bangalore. IISc has developed a complete unit for generation of power using a gasifier coupled with a diesel engine. The technology is being marketed by NETPRO Renewable Energy (India) Ltd., a company based in Bangalore. This design was selected by DESI Power for installation at Orchha.

A plant capable of generating 80 kW of electricity was installed at Orchha in April 1996. The system has been running for more than a year, meeting the power requirements of TARAGram. The operation of the plant for such a long duration has led to a variety of experiences which will be discussed subsequently.

For a plant being operated on a commercial basis, the financial arrangement is a crucial aspect to be taken care of. The modus operandi of DESI Power includes setting up of Independent Rural Power Producers (IRPPs), in different regions of the country. These IRPPs will be companies, which will own a cluster of power plants set up in that region. These companies will have equity contributions from DESI Power, as the promoter of IRPP, as well as from local partner(s), who could be the beneficiary or the user of the power generated by the plant. A part of the capital will be met from government grants and/or loans from funding agencies or banks.

The plant in Orchha has been set up following such a model. An IRPP called DESI Power Orchha, has been set up which owns the plant. A part of the funding for the plant was provided by the equity contributions from DESI Power (26 percent), TARA (26 percent) and 48 percent from Fund for Renewable Energy Decentralised (FREND), a society registered in Switzerland. Here, TARA is the local partner which is also the user of the power. The rest of the capital requirement was partly met by a loan from Small Industries Development Bank of India (SIDBI) and partly by a subsidy from Ministry of Non-conventional Energy Sources (MNES). The total cost of the plant worked out to be about Rs.21 lakhs. DESI Power Orchha, is responsible for the operation and maintenance of the plant and sells the power to TARA.

Biomass being the feedstock for the gasifier, its management is a crucial aspect in the operation of the plant. In Orchha, it was decided to use ipomea as a feed for the gasifier. This weed grows in marshy lands and near water bodies. The woody part of the weed needs to be harvested and then chopped into smaller pieces. The biomass, in this form is still green and needs to be dried to a low moisture content before it can be fed into the gasifier. Adequate storage capacity is needed to take care of rainy days.

It is natural to employ the local population for the above tasks. In the beginning, the work was given to residents of nearby villages on daily wages. The biomass was harvested manually and then chopped using manually operated machines provided by DESI Power Orchha in the villages. The cut biomass was delivered at the plant site by the villagers, where it was sun-dried. The cost of harvesting and chopping was fixed considering the capacity of an average individual to complete the task and the minimum daily wages they should be able to earn. The cost of transportation of biomass using bullock carts was taken to be the prevalent rates per trip of the cart. This arrangement posed continuous problems, since it was very difficult to monitor the work being done by the workers. The cost of the biomass turned out to be much higher than the expected rate.

In an attempt to reduce the cost of biomass, it was decided to give the entire work of harvesting, chopping and transportation on contract and pay per unit of the cut biomass delivered at the site. However, it was extremely difficult to get any villager to agree to take the contract at the rates offered by the company. Finally, only one person agreed to take it up but at a higher cost. This arrangement is working well for more than six months now, but has resulted in the cost being high.

The economics of procuring biomass may vary from region to region but the cost of biomass will certainly be a considerable part of the cost of electricity generation. Studies have already been initiated to find solutions for reducing the cost of dry biomass in Orchha.

The power generation unit based on the gasifier was commissioned on April 1997. Since then, the gasifier has logged about 2,500 hours of operation, running nearly 10-12 hours per day during normal operation. The diesel replacement recorded in the system has been as high as 85 percent at times. Since the diesel replacement depends on the plant load factor, the average replacement obtained is about 70 percent.

Performance Gasifier Operation Electricity generated Average diesel replacement

2,500 hrs 73,000 kWH 70 percent

The long duration of operation has provided valuable data about the performance of the plant. This data is currently being analysed. Valuable experience has also been gained in the maintenance of the plant. The commercial application of the technology being still in its infancy, the information about the maintenance requirements of many components and their average life can be obtained only through experience. Though the actual life of different components will depend on the characteristics of the biomass, the experience in Orchha can help in framing the general guidelines for improving the specifications of components and materials, as well as the procedures and systems for maintenance and management of power plant based on woody biomass gasifier. The experience in Orchha has also led to modifications and improvements in the system, so as to make the technology more robust and more suitable for field applications.

The plant can be satisfactorily operated and maintained by employing three personnel - one operator and two assistants - per shift. The plant is generally operated in two shifts. The local people have been trained and employed for the task. A system has been evolved for maintaining detailed records of the performance and the maintenance requirements of individual components of the system, fuel procurement and consumption. This information will be valuable in analysing the performance of the system and in imparting training to the personnel for the future plants.

The cost of electricity produced is presently being worked out based on actual expenses incurred in installation and operation of the plant. Apart from the biomass price, the generation cost is also highly dependent on the plant load factor and the extent of diesel replacement which is affected by the plant load factor and load variations demanded by the operational requirements of the paper mill.

Estimates indicate that in the first year when the plant was commissioned and the operations were still being stabilised, the cost of generation had been higher than projected. Under the rather adverse conditions of a low load factor, very high biomass cost, and lower than optimum diesel replacement caused by large variations in the plant load, the cost of electricity works out to be about Rs.4.00 per kWH, which is almost the same as the cost of electricity from the grid. A plan of action is being worked out to bring down the price of electricity by a number of measures such as increasing the load factor by adding to consumption during off-peak hours and by improving the diesel replacement.

Electricity Users Hand-made paper unit Building material: * MCR tiles * concrete blocks * ferrocement channels * compressed earth blocks * RCC door and window frames

This is a crucial aspect in the management of the plant to ensure an effective utilisation of the plant capacity. In Orchha, the connected load is about 100kW. However, the continuous loading has been low as well as fluctuating. The reasons for this are linked to the multiplicity of factors affecting the operation of various machines in the paper unit, which is the main consumer of power at TARAGram. The load also comes down in the rainy season due to the long time taken for the paper to dry, leading to reduction in the paper production. Monitoring the time variance of the load is not an easy task. Certain machines like the calendering machine used in the paper unit result in a highly fluctuating load due to the frequent drawing of a large current. This reduces the plant load factor considerably and also raises the cost of electricity generation. Attempts are being made to improve the load management so as to increase the plant load factor. Another step being considered for improving the plant load factor is the charging of electric lanterns. These lanterns can be given on lease to the local people, including the employees of TARAGram, who can use them for lighting their houses. Water pumping is another possibility for improving the load factor.

Operational experience at Orchha has indicated that the management of spare parts and consumables needs to be improved. Spare parts have to be stocked at the plant so as to reduce the plant down time. This will reduce the outage time and hence contribute to the improvement in the plant utilisation and a reduction of diesel consumption.

The plant has been planned to be a cogeneration unit but till now only the electric energy from the gasifier system has been utilised. However, utilisation of thermal energy, available as waste heat in the cooling water and in the exhaust gas from the engine has been planned. This heat can be used for drying paper which can, then, solve the problem of low production of paper in the rainy season and thus increase the annual plant load factor. Cold storage units based on waste heat are planned to be included in the other IRPPs.

The producer gas from the gasifier needs cleaning and cooling before it can be used in the engine. The waste water from the cooling-cum-cleaning unit contains contaminants which can make this water unfit for discharge into the environment unless it is highly diluted. A treatment system is being developed for the wastewater, which will also lead to a reduced requirement of fresh water.

Employment Plant Operation Biomass supply Industry 80

6 23 80

The Orchha experience has established the technical as well as economic viability of commercial operation of decentralised power plants based on locally available resources. It has also provided an experience for the financial packaging and the operational and financial management of such plants. The plant has demonstrated that the local population can be trained to operate and maintain such units. The lessons learnt should lead to further improvements and measures for more effective diffusion of the technology.

DESI Power plans to replicate this experience at other locations around Orchha and different regions of the country. In a Commercial Demonstration Phase, 20 such plants in clusters of four or five units will be set up in various parts of the country. The optimum number of units per cluster of similar IRPPs may be about 10, with a total installed capacity of about 1 MW. Initially the plants installed will be based on gasification technology. Subsequently, other locally available renewable sources of energy would also be considered.n

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