Each year, the world uses enough electricity to turn Lake Erie into a hot tub for a day, around 23,000 TWh. Most of this power flows through transformers, so they’re a crucial part of our road to net zero, says Christina Iosifidou, head of sustainability, grid technologies at Siemens Energy and advisory board member for electrical engineering trade show, CWIEME Berlin.

According to the European Commission, 93 TWh of electricity is wasted annually in Europe due to transformer losses. That's more electricity than all the renewable sources in the UK produced in 2023 and about three per cent of all the energy generated across Europe.

Transformer losses, though usually only one or two per cent of the load, add up over the transformer’s expected 35-year operation phase and represent more than 95 per cent of its total carbon footprint. Manufacturing the transformer in the first place, delivery and installation make up the other five per cent.

Naturally, improving transformer efficiency continues to be a topic for constant research and development and is in the DNA of any transformer manufacturer. The numbers have improved over time and the European Commission’s Ecodesign Directive now demands minimum transformer efficiencies of up to 99.77 per cent. Efficient transformers are more expensive, though, and efficiency also often comes at a cost to compactness.

You are what you eat

Eventually, we’ll meet the boundaries of physics — some energy will always be lost to things like hysteresis, eddy currents and Joule heating. Because most of a transformer’s carbon footprint comes from these unavoidable losses, a transformer can only truly be green when the electricity it’s fed is green.

While renewable electricity is freely available in some geographies, the origin of the electricity a transformer receives is out of our hands as OEMs. It’s up to governments to facilitate the extensive development required to make green electricity the norm.

What can OEMs do?

One way manufacturers can reduce a transformer’s carbon footprint is to decarbonise the production process as much as possible. For example, a major portion of emissions from a transformer factory comes from drying and oven processes. Traditionally, the ovens are heated using fossil fuels, so electrifying them and feeding them 100 per cent renewable electricity would significantly reduce carbon emissions. Indeed, all four ovens in one of Siemens Energy’s factory at Nürnberg are now electric and run on renewable power.

However, just like with electric vehicles, making the switch before sufficient green electricity is available at a facility negates any reduction in emissions.

Using sustainably sourced materials wherever possible is another way to decarbonise supply chains. In fact, more than 90 per cent of manufacturing emissions comes from raw materials and, of that, around 85 per cent comes from copper and steel. Switching to green steel and using responsibly sourced copper can make a big difference, but doing this might be harder in some geographies or developing countries due to the significant investment required. For example, converting one out of four coal-fired blast furnaces to hydrogen-fired cost thyssenkrupp around 2 billion euros.

All this points to why we need to plan for a transition period which includes and involves the entire value chain. It’s important because manufacturers, large OEMs especially, have the power to shape the industry by demanding responsibly produced materials from suppliers.

That’s where events like CWIEME Berlin can help. Getting everyone under one roof makes it possible to discuss critical topics like these. Through international collaboration and the exchange of ideas across the whole value chain, we can continue making progress towards net zero. Once we get there, let’s all go to Lake Erie to celebrate.