In the Bureau of Energy Efficiency Bhubaneswar melting furnace reports for 30, 60 and 100 kg, why do the rupee savings and the carbon dioxide cuts use different coke tonnes?

Each Bureau of Energy Efficiency (BEE) Bhubaneswar report credits the owner of a shared melting furnace with the coke saved by his unit plus half of two neighbours' saving, 5,323, 10,646 and 13,910 kilograms, but prints carbon dioxide on all three units, 1.5 times as much.

The three reports side by side

• 30 kilogram (kg) furnace: coke saved 5,323 kg a year. Cost rupees (Rs) 1.32 lakh, saving Rs 0.44 lakh, payback 3 years, net present value (NPV) Rs 0.38 lakh, internal rate of return (IRR) 18.23%.
• 60 kg furnace: 10,646 kg. Cost Rs 1.80 lakh, saving Rs 0.88 lakh, payback 2.05 years, NPV Rs 1.60 lakh, IRR 34.05%.
• 100 kg furnace: 13,910 kg. Cost Rs 2.06 lakh, saving Rs 1.15 lakh, payback 1.79 years, NPV Rs 2.37 lakh, IRR 40.59%.
• Common to all three: 144 batches a year, hard coke at Rs 8.5 a kg, a new furnace at 15% efficiency, and a small electric blower. The old furnaces are rated 3.91%, 3.91% and 4.65%, using 0.83, 0.83 and 0.70 kg of coke per kg of brass.

Two sets of coke tonnes in one report

• The reports assume one furnace serves three units. The annexure shows the owner's own unit saving, the two neighbours' saving, and an amount the neighbours share with him. For the 30 kg report: own 2,662 kg, neighbours 5,323 kg, shared 2,662 kg, so 2,662 + 2,662 = 5,323 kg is counted for the owner's money.
• The carbon dioxide (CO2) text uses the whole group instead: 7,985 kg for 30 kg, 15,970 for 60 kg and 20,866 for 100 kg. Each is 1.5 times the money figure (my arithmetic).
• Printed CO2: 21, 43 and 56 tonnes a year, about 2.6 to 2.7 kg of CO2 per kg of coke.
• At the 3.02 kg of CO2 per kg that the Intergovernmental Panel on Climate Change (IPCC) 2006 defaults give for coke oven coke (107,000 kg a terajoule at 28.2 terajoules per gigagram), the group saving is about 24, 48 and 63 tonnes. That assumes the hard coke behaves like coke oven coke, which is my assumption. Our Bhubaneswar melting page counts the 100 kg saving the same way, about 63 tonnes.

Which figure is yours

• For your own emissions, count the coke your own unit burns and what it saves: 2,662, 5,323 and 6,955 kg in the three reports, or about 8, 16 and 21 tonnes of CO2 at 3.02 (my reading of the annexure).
• The three-unit total belongs to the group that shares the furnace, not to one owner.
• The reports assume the two neighbours rent the furnace and pay the owner 50% of their coke saving as rent. The owner's rupee saving includes that rent, so it only holds if they actually pay it.

Printed figures to check

• The 30 kg table prints the blower at 438 kilowatt hours (kWh) but charges Rs 1,112, which is 484 kWh at Rs 2.3; 0.37 kilowatts for 1,296 hours is 480 kWh.
• All three annexures use 1,296 operating hours, which is 3 units x 144 batches x 3 hours. The 60 kg report's batch is 4 hours, so its hours would be 1,728 on that basis. The effect on payback is small (my reading).
• Fossil CO2 from the blower is about 0.3, 0.7 and 0.9 tonnes a year at 0.675 kg per kWh.

The 60 kg furnace, report sums

• Old: 7,200 kg of coke a year at 3.91%. New at 15%: 7,200 x 3.91 / 15 = 1,877 kg. Own unit saves 5,323 kg
• Counted for the owner: 5,323 + 5,323 shared = 10,646 kg x Rs 8.5 = Rs 90,491, less blower Rs 2,236 = Rs 88,259. Payback Rs 1.80 lakh / Rs 0.88 lakh = 2.04 years (2.05 printed)
• Group CO2 basis: 10,646 + 5,323 = 15,970 kg x 3.02 = about 48 tonnes. Own unit: 5,323 x 3.02 = about 16 tonnes

Prices are the reports' own. The coke factor is the IPCC 2006 default for coke oven coke; whether it fits your hard coke is an estimate.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the coke your own unit buys is on file, which is the figure to report. It does not apportion a shared furnace between neighbours.

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Sources: BEE, Detailed project report: energy efficient melting furnace, 30 kg, Bhubaneswar brass cluster (SAMEEEKSHA).pdf), BEE, Detailed project report: energy efficient melting furnace, 60 kg, Bhubaneswar brass cluster (SAMEEEKSHA).pdf), BEE, Detailed project report: energy efficient melting furnace, 100 kg, Bhubaneswar brass cluster (SAMEEEKSHA), IPCC 2006 Guidelines, Volume 2 Energy (default carbon content, net calorific values and emission factors)

Last reviewed 2026-11-06. Report figures are from BEE's Small and Medium Enterprises (SME) programme project reports; costs, coke price and paybacks are at the report year's prices. Redo the payback with today's coke price and a current quote.