The spread that pays for everything.

Britain's electricity is made substantially from gas, yet a business pays roughly three times more for a unit of electricity than for a unit of gas. The difference is generation losses, network charges and levies, stacked onto every kWh the grid sells you.

Burn the same gas on your own site at 90%+ efficiency and most of that difference becomes yours. That gap, the spark spread, has persisted through twenty years of price history and every energy crisis in living memory, because the physics that creates it doesn't change with the wholesale market. How the machine captures it is on how it works.

It's worth being precise about what the saving is not. It is not a hedge, a tariff trick or a subsidy. It survives price spikes because gas and electricity prices move together, which keeps the gap open. When the mill in our West Yorkshire case cut its energy costs by more than half, that was the spread doing the work.

And because the saving comes from efficiency, the carbon falls with the bill: the same fuel does more work, so less of it is burned. That side of the ledger is on sustainability.

It's why on-site generation lands around 10p per kWh all-in against grid rates of 22 to 30p. Not a discount. Arithmetic.