Energy does not flow in a single form

When people talk about a plant’s energy bill, they think first of electricity. But a plant consumes energy in several forms, called carriers: electricity, steam, compressed air, fuel, cooling. Each carrier is produced, transported and used differently, with its own losses. Understanding this variety is knowing where the money and the carbon actually go.

Electricity

It is the most versatile carrier: motors, lighting, electronics, heating. It travels with no significant loss across a site and converts easily. Its cost reads straight off the meter, which makes it the most closely watched carrier. Electricity’s share of the industrial mix keeps growing as processes electrify.

Steam

In heavy industry — chemicals, food, paper — steam is the great heat carrier. Raised in a boiler, it carries energy to exchangers and reactors. Its weak point: line losses, faulty steam traps and unrecovered condensate heat. A poorly maintained steam network can lose a notable fraction of the energy it produces.

Compressed air: the most expensive carrier

Compressed air is everywhere — cylinders, valves, tools — because it is convenient and safe. But per useful kWh it is the most expensive carrier in the plant: producing compressed air has a very low efficiency, most of the compressor’s electricity ending up as heat. Add to that leaks, which alone can account for a large share of a network’s consumption. Hence the rule: never use compressed air where electricity would do.

Fuels

Natural gas, oil, biomass feed furnaces, boilers and cogeneration. They are the main source of a plant’s direct CO₂ emissions, which makes them the central target of decarbonisation. Their cost is volatile and exposed to the price of carbon.

Cooling and utilities

Cooling (chilled water, refrigeration units) is a carrier in its own right, a heavy electricity consumer in food and pharma. Alongside it, utilities gather cooling water, demineralised water, nitrogen, vacuum: quiet services that nonetheless weigh on the bill.

Each carrier has an efficiency

Carrier	Indicative efficiency / losses
Electricity	near-lossless transport across a site
Steam	10–20% network losses common
Compressed air	8–15% overall efficiency; 20–30% leaks
Cooling	COP ~3–5 (3 to 5 kWh of cold per kWh of electricity)

The lesson is simple: a kWh does not have the same cost or efficiency depending on its form. Converting electricity into compressed air, then compressed air into motion, stacks up losses. Reasoning carrier by carrier and metering each separately — which an energy performance indicator (EnPI) formalises — is the basis of any efficiency effort, and an OPEX line you can genuinely cut.