DESI Power is a not-for-profit collaboration between DASAG India and TARA, (the commercial wing of Development Alternatives), dedicated to the promotion of renewable energy. It sets up Independent Rural Power Producers (IRPPs) at the village level as joint ventures with local communities and entrepreneurs.
   
DESI Power has been established to provide electricity to remote villages not connected to the national power grid.
   
The first set of innovations is in the technologies used: improved gasifiers, co-generation applications, domestic appliances. The second set is innovations in financial engineering equally critical to the success of the IRPPs. The third set of innovations is in the institutional framework, which is designed to help the local IRPPs (or clusters of IRPPs), which are independently registered as companies, not only to raise investment capital at minimum possible cost, but also to involve the local community in the management and operation of the plants.
   
Biomass Gasification

Despite these problems, a few renewable energy technologies are breaking in to the Indian electricity generation scene: mainly wind, biogas (methane from fermentation of biomass) and producer gas (carbon monoxide and hydrogen from partial combustion of biomass). One promising technology for village applications appears to be the last of these, biomass gasification. The technology has been known for quite long, and was used extensively in Germany, and also in Britain and even India during the second world war when oil and gas became scarce. The gas produced by a biomass gasifier is fed into an internal combustion engine which can then drive an electrical generator, substituting 80% or more of the diesel fuel.     After several years of intensive and careful research, scientists at the Indian Institute of Science (IISc) developed a highly innovative design for a gasifier that produces virtually 100% pure combustible gas. The design, featuring a unique gasifier geometry, scientifically configured temperature profile in the combustion chamber and a novel sequence of filters, makes this among the most advanced gasifiers available anywhere.     The IISc gasifier is manufactured commercially by NETPRO, a Bangalore based engineering company to which the Institute has licensed the know-how. The gasifiers can currently be supplied in sizes ranging from 20 kW to 1 MW. It is this gasifier which DESI Power has chosen for its commercial demonstration phase, mainly in the range below 100 kW. IISc is closely associated with the implementation and monitoring of the first few units, both to help debug technical problems and to get feedback from actual performance of the gasifiers in the field for further refinement of the design.     Financial analysis of a typical gasifier-based power station quickly shows that three factors are critical in determining its financial performance: the cost of capital, the load factor and the cost of the fuel.

DESI Power Plant producing electricity from Biomass

DESI Power Orchha
   
The first DESI Power plant was installed at Orchha in Madhya Pradesh, near Jhansi, a five hour train ride south of Delhi. This plant has now been operating for more than three years. It is located at and supplies power to TARAgram, a campus where TARA carries out research, demonstration, training and production activities using appropriate technology. TARAgram’s manufacturing facilities employ more than a hundred workers. They include a large handmade recycled paper unit, several enterprises producing microconcrete roofing tiles, mudblocks, ferrocement and other low cost building materials, a charcoal briquetting unit and a paper products unit. Additional production units are continually being added. Although TARAgram now also has acquired a grid connection, the bulk of its electricity requirements are still met by the DESI Power plant.
    
As for all DESI Power stations, a careful site analysis and feasibility report was prepared for the Orchha plant to assess the potential demand for electricity in the neighbourhood, the availability of renewable fuels and the existence of interested partners for setting up an IRPP. To do this, the studies investigated possible clients, number of diesel generators currently in use, purchasing power of households for lighting and appliances, possible mini industries suitable for the region and the existence of alternative sources of power – including the grid. For availability of biomass fuels, surveys were conducted of the availability and calorific value of local agrowastes, industrial wastes, common weeds. Other factors studied included identification of potential partners, accessibility of local investment capital and availability of local management and operator skills, etc.
   
A survey of the region around TARAgram showed that two weeds - ipomea and lantana camera - were abundantly available in the region. Ipomea was so pervasive and so prolific that the local people call it "besharam" or shameless. It covers large areas, growing along the banks of water bodies and in marshy areas. Despite having considerable calorific value, it is not used by local people for any purpose. It is no good for cooking since it burns with an obnoxious smell. It is not eaten by animals and has no use as a fibre. Lantana, on the other hand, is commonly used as a fuel for cooking. It is also good for making handicrafts and furniture.
   
On the basis of these studies, an 80 kW power station was ordered in December 1995. The DESI Power Orchha (DPO) unit, located at TARAgram, went into operation four months later in April 1996. The capital cost of the station was Rs. 22 Lakhs. Initially, the sole client was TARA. Ipomea was the fuel.
   
Managing Biomass Fuels
   
An 80 kW plant needs almost one tonne of biomass fuel every day. Managing the neighbouring biomass resources properly becomes crucial for reliable plant operation. 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 reduce moisture content before it can be fed into the gasifier. Adequate covered storage capacity is needed to take care of rainy days and supply hold-ups. Furthermore, over the years, the supply of ipomea needs to be sustained at reasonably constant levels and prices.
    
Several methods for procuring the ipomea were tried. Not all were successful, and sometimes the trial of one method ruled out another because of the local perceptions (as to its worth, etc.) it created. In the early stages, DPO tried to manage the process itself, hiring workers for each operation and paying them daily wages. The productivity of such a system was found to be low, and the effective cost of the fuel high. Subsequently, and in keeping with its market-oriented philosophy, DPO decided to commercialise the procurement of ipomea fuel by offering a price at which it was willing to purchase ipomea. The prices offered were designed to add up to a minimum daily wage or to the prevaling rates for transportation. The actual prices negotiated had to be higher and the effective cost of dry fuel now exceeds the economically desirable level.
   
More than ten local families have now created new livelihoods, harvesting, chopping and transporting the weed and delivering it to the power station, where it is sun-dried before being fed into the gasifier. However, the cost of fuel is adding some 20% more than it should to the final cost of electricity produced. Biomass costs may well vary from region to region but the empirical finding is that they are certainly a significant component of the cost of electricity generation and must be contained to keep DESI Power competitive. Solutions are being sought to reduce these costs.
   
The Economics of an IRPP
  
The plant can be satisfactorily operated and maintained by three personnel - one operator and two assistants - per shift. The plant is generally operated in two shifts. Local people, with minimum education can be trained and employed for the tasks. DPO triggered employment of more than 100 workers in the factories that purchase electricity from it.
   
Over the past three years, the gasifier has logged about 5,000 hours of operation, running nearly 10-12 hours per day during normal operation. The percentage of diesel replaced by gas depends on the plant load factor. It has been recorded as high as 85%, though the average is currently about 75 per cent. Competitive pricing of electricity will require DESI Power stations to maintain an average of well above 80%.
    
The extensive and thorough testing of the technology at DPO has provided detailed operational and maintenance data which will be invaluable for designing future plants. It has also led to significant modifications and improvements in the system, so as to make the technology more robust, safe and suitable for field applications.
   
Provided investment capital is obtained on terms similar to those available to large IPPs, DPO has clearly shown that the cost of electricity produced by such a plant can be highly competitive with conventional systems. The two most sensitive determinants of production cost have been confirmed to be: i) the cost of biomass fuel and ii) the plant load factor achieved. The cost of biomass fuel has been discussed above. The higher the plant load factor, the lower the production cost for two reasons: first, because it spreads the costs of capital and overheads over a larger quantity of electricity and second, because it raises the diesel replacement rate, reducing the use of costly diesel fuel.
  
As shown both by the theoretical calculations and the actual experience of DPO, plant load factor (PLF, another term for capacity utilisation) is a critical parameter to which the economics of power generation is extremely sensitive. This is so for large power plants, but even more so for small ones. The breakeven PLF for DPO is between 50% and 60%. Above 60%, DPO will be highly competitive and able to sell electricity at prices below the grid. Even with less than the very low 40% load factor, very high biomass cost, and lower than optimum diesel replacement caused by large variations in the plant load, the cost of electricity has worked out to be in the range Rs.4.00 to Rs 4.50 per kWH, which is quite competitive with electricity from the grid.
   
The Future
   
Efforts are being made to raise the PLF at Orchha by adding new clients and industries with energy-intensive applications, reducing the high fluctuations in some of the loads (e.g., the calendaring machine in the paper unit) and staggering certain activities.
   
The co-generated heat from the exhaust of the diesel engines in the DPO plant is fed to the drying rooms of the paper unit, adding value and improving its economics. Other applications for the heat from the gasifier and the diesel engines are being investigated to improve its utilisation further. One of the most attractive options appears to be cold storage units based on the waste heat.
   
Environmentally, DPO has generally surpassed expectations. Treatment for the waste water from the cooling-cum-cleaning unit which contains contaminants is constantly being improved to permit the effluent to be discharged into the surroundings with some dilution.