What do the Bureau of Energy Efficiency Bhubaneswar rice husk gasifier reports for 30, 60 and 100 kg furnaces assume about the two neighbours who rent the gasifier?

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In the three Bureau of Energy Efficiency (BEE) Bhubaneswar gasifier reports, the yearly benefit of rupees (Rs) 3.11, 4.86 and 7.41 lakh needs two neighbours to rent the gasifier. Without them my sums give paybacks of about 4.7, 4.4 and 4.0 years, not the printed 2.27, 2.08 and 1.88. 30 kilogram (kg) furnaces: cost Rs 7.05 lakh, benefit for the main unit Rs 3.11 lakh, payback 2.27 years, net present value (NPV) Rs 4.02 lakh, internal rate of return (IRR) 25.92%. Rice husk for the three units: 6,426 kg a year. 60 kg: Rs 10.13 lakh, Rs 4.86 lakh, 2.08 years, NPV Rs 7.28 lakh, IRR 29.77%. Husk 12,852 kg. 100 kg: Rs 13.92 lakh, Rs 7.41 lakh, 1.88 years, NPV Rs 12.84 lakh, IRR 34.95%. Husk 22,890 kg. All three: producer gas furnaces taken at 25% efficiency on a gasifier at 75%, husk at Rs 1.5 a kg and 2,500 kilocalories (kcal) a kg, hard coke at Rs 8.5 and charcoal at Rs 22.5, eight days of downtime. The main unit owns the gasifier. Two neighbouring units of the same size use it and pay rent. 30 kg report: own saving Rs 28,573 on melting plus Rs 1,28,414 on reheating, and rent of Rs 30,600 plus Rs 1,29,600. Less electricity of Rs 6,043. Net Rs 3,11,144. The rent lines are exactly half of the two neighbours' old fuel: 3,600 kg of coke and 5,760 kg of charcoal at the old prices. That is slightly more than a whole unit's own saving after husk, so the rent is about 102% of what the main unit saves for itself (my arithmetic, same pattern in the 60 and 100 kg reports). So more than half of each printed benefit is rent from neighbours. Own saving less all the gasifier's electricity: 30 kg, Rs 1,50,944, so Rs 7.05 lakh pays back in about 4.7 years. 60 kg, Rs 2,30,637, about 4.4 years. 100 kg, Rs 3,47,763, about 4.0 years (my arithmetic, assuming one unit carries the whole power bill). Whether neighbours will pay half their old fuel bill, month after month, is the real decision. Agree the rent and the husk supply in writing before you borrow. The annexure does not show the neighbours' own husk bill. At Rs 1.5 a kg it is about Rs 3,200, Rs 6,400 and Rs 11,400 a year for each neighbour (my arithmetic). Printed: 79, 133 and 205 tonnes a year, about 2.8 to 2.9 kg per kg of the hard coke and charcoal replaced across the three units. Charcoal and rice husk are biomass. The reheating furnace reports from the same programme leave charcoal CO2 out for that reason, so these figures do not follow the same rule. Fossil only: the hard coke across three units is 10,800, 21,600 and 30,240 kg. At the 3.02 kg of CO2 per kg that the Intergovernmental Panel on Climate Change (IPCC) 2006 defaults give for coke oven coke, that is about 33, 65 and 91 tonnes, less the blower power at 0.675 kg per kilowatt hour (about 2, 5 and 10 tonnes), so about 31, 60 and 81 tonnes. The hard coke may not match coke oven coke, so treat these as estimates. For the 100 kg furnace the gasifier report takes reheating efficiency at 1.65%, while the 100 kg reheating furnace report from the same programme computes 1.38% from 95 kg of charcoal a batch. At 1.38% the reheating husk would be about 2,618 kg, not 3,130 (my arithmetic). The rupee effect is small because husk is cheap, but a lender comparing the reports will see two baselines for one unit.

What do the Bureau of Energy Efficiency Bhubaneswar rice husk gasifier reports for 30, 60 and 100 kg furnaces assume about the two neighbours who rent the gasifier?

The three reports side by side

Where the main unit's benefit comes from

Payback if the neighbours do not rent

Carbon dioxide (CO2): printed and fossil only

One baseline that moves

The 30 kg gasifier, report sums

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