How much energy does compressed air take in a tannery, and what does fixing leaks save?
The European tanning reference document puts compressed air at about 5 cubic metres per square metre of leather, or 0.35 to 0.40 gigajoules (GJ) per tonne of raw hide. It says 10 to 30% is normally wasted, mainly through leaks, and an overhaul can often save 0.10 GJ per tonne.
The figures the document prints
- Compressed air is by far the most expensive form of energy in a tannery. Use is estimated at 5 cubic metres per square metre of leather, which it equates to 0.35 to 0.40 GJ per tonne of raw hide.
- In practical systems there is normally a waste of 10 to 30%, mainly leaks. An overhaul can often save 0.10 GJ per tonne of raw hide.
- Waste heat from the compressor, used for water heating or space heating, can recover 80 to 90% of the compressor's energy.
- A compressor running idle or at low load uses almost the same as one at full load. Smaller units, one for the base load and one for peaks, are more economical than one big unit.
How big it is next to the whole tannery
Against the survey's 9.3 to 42 GJ per tonne of raw hide, 0.35 to 0.40 GJ is about 0.8% to 4.3% (0.35 / 42 and 0.40 / 9.3). The document's own table gives pressurised air 1.5 to 3% of total energy. These are close enough to say compressed air is small next to drying and hot water, but worth a leak survey because the document's table counts it as electricity.
A second source, a different industry
The Energy and Resources Institute (TERI) profile of Agra footwear component plants says air leaks there are often more than 20% and can be cut to about 5% with good operating practice. Lowering the compressor pressure by one bar can save 5 to 6%, in TERI's words. Those are plastic moulding plants, not tanneries, but the leak range overlaps the document's 10 to 30%. TERI says leaks in most cases are more than 20%. Each figure on this page and on the live pages comes from a different source and plant type: the live compressed air pressure page gives 6 to 10% per bar from India's Bureau of Energy Efficiency (BEE) guide book, the live leak page says leaks waste 20 to 30% and a well-kept system loses under 10%, and the live heat recovery page says 50 to 90% of the heat is recoverable, against 80 to 90% here.
What the bill can and cannot show
The electricity bill shows total kilowatt hours (kWh), not how many go to the compressor. Without a sub-meter on the compressor, you can only see a fall in the month after a leak repair if nothing else changed. Keep a note of the repair date next to the month's bill.
Example: 100 tonnes of raw hide a month
- Compressed air at 0.35 to 0.40 GJ per tonne: 35 to 40 GJ a month
- 1 GJ = 277.8 kWh, so 9,722 to 11,111 kWh, if all of it is electricity (the document does not say)
- Emissions at 0.675 kilograms of carbon dioxide (CO2) per kWh for financial year (FY) 2025-26: 6,562 to 7,500 kilograms (kg) a month
- An overhaul saving 0.10 GJ per tonne: 10 GJ = 2,778 kWh = 1,875 kg of CO2 a month
The 100 tonnes is an example. The 0.10 GJ saving is "often", in the document's words, not a guarantee for your plant.
What Senseible does here
Senseible reads fuel invoices and electricity bills into records by billing period, so the kWh before and after a repair sit side by side. You note the repair date. It does not meter compressors.
- Where a tannery's energy goes
- Air compressor heat recovery savings
- Agra footwear component cluster energy
- Compressed air pressure reduction savings
- Compressed air leak cost and emissions
Sources: European Commission, Integrated Pollution Prevention and Control (IPPC) Reference Document on Best Available Techniques for the Tanning of Hides and Skins, February 2003 edition (filed by the publisher as superseded), TERI, Cluster profile: Agra footwear industries (2015, data for 2014-15), CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0
Last reviewed 2026-11-06. Figures are from the February 2003 edition of the European tanning reference document, which the publisher files as superseded; its energy and effluent tables rest on European tanneries and on older studies. Check the current edition and your own records before you quote a number to a buyer.