EMS and JOPEA hold an ‘Energy Saving Methods and Mechanisms in the Olive Sector seminar

Behind an unglamorous seminar title — energy saving in the olive sector — sits one of the least romantic and most important truths about olive oil. Turning fruit into oil is an industrial process that burns energy and produces a stubborn, polluting waste. How mills handle that shapes their cost, and the environment.

The event itself was modest : an energy-management firm and an olive exporters’ association holding a seminar on saving energy in the olive sector. Easy to ignore. But that dry title points straight at a side of olive oil the marketing never shows — the industrial reality of a working mill, where fruit is turned into oil at real cost in power, water and waste. It is worth understanding, because it quietly shapes the price and footprint of every bottle.

Making oil takes real energy

A modern mill is a factory. Crushing, malaxing and especially spinning the paste in high-speed centrifuges all draw significant electricity, often concentrated into the few frantic weeks of harvest when every mill in a region runs flat out at once. Add the pumping, heating of water, lighting and cold storage, and energy becomes one of a mill’s largest running costs. In a low-margin business, shaving that bill is not a green nicety — it is survival, which is exactly why seminars like this exist.

The waste nobody puts on the label

Here is the part the industry would rather not discuss. Pressing olives leaves two big by-products : pomace, the solid mush of skins, pulp and crushed stones, and a dark, acidic, foul-smelling liquid effluent — the notorious ‘black water’ of olive milling. That liquid is genuinely problematic : rich in polyphenols and organic load, it can foul waterways and soil if simply dumped, and disposing of the seasonal flood of it is one of the Mediterranean olive industry’s oldest environmental headaches.

Turning the problem into fuel

The encouraging twist is that much of this waste has value if handled cleverly. Pomace still contains residual oil, which can be extracted (the origin of cheap ‘pomace oil’), and the dried solids make a genuine biomass fuel — mills can literally burn their own leftovers to power the next crush. The dark water is harder, but can be treated, spread carefully, or processed to recover its compounds. This is the real content behind an ‘energy saving’ seminar : closing the loop so a mill’s waste becomes its fuel, cutting both the bill and the pollution at once.

Why mills use energy	Crushing, malaxing, centrifuging, pumping, storage
When it peaks	The few intense weeks of harvest, all at once
Solid waste	Pomace — skins, pulp and crushed stones
Liquid waste	Dark, acidic olive-mill effluent (‘black water’)
The risk	Untreated effluent can foul soil and waterways
The opportunity	Pomace as biomass fuel; residual oil; treated water

Why a shopper should care

• Cheap ‘pomace oil‘ is extracted from the milling leftover — a different, lesser product than extra virgin.
• A mill’s energy and waste handling feeds into the true cost of honest oil.
• Better mills increasingly reuse their own waste as fuel, cutting cost and pollution.
• The industrial reality behind the bottle is part of what good oil really costs.

Olive-mill energy and waste: common questions

Does making olive oil use a lot of energy?

Yes. Crushing, malaxing and high-speed centrifuging draw significant power, concentrated into the intense weeks of harvest, making energy one of a mill’s biggest costs.

What is olive pomace?

The solid by-product left after pressing — skins, pulp and crushed stones. It still holds residual oil and can be dried and burned as biomass fuel.

What is olive-mill ‘black water’?

A dark, acidic, strong-smelling liquid effluent from milling. Rich in polyphenols and organic load, it can pollute soil and waterways if dumped untreated.

Is pomace oil the same as olive oil?

No. Pomace oil is extracted from the milling leftover, usually with solvents and refining. It is a cheaper, lesser product, not extra virgin olive oil.

Can olive-mill waste be reused?

Yes. Pomace makes biomass fuel and yields residual oil, and the dark effluent can be treated or processed — turning a pollution problem into a fuel and cost saving.

Drawn from the themes of an olive-sector energy-efficiency seminar, and on olive-mill by-products — pomace and dark effluent — and their reuse as fuel and treated water.