From trash to treasure

Our cities are responsible for more than three-quarters of a country’s economic output, but to run their activities, they require an uninterrupted supply of energy.

According to UN-Habitat cities worldwide also consume about 75% of primary energy sources, and emit between 50 and 60% of the world’s total greenhouse gases. That figure rises to approximately 80% when indirect emissions generated by the people within urban areas are included – things like transport, lighting, air conditioning.

The energy transition is at the heart of the kind of sustainable development that’s needed to spur change – whether it’s modernising and diversifying the economy, improving air quality or combating climate change - and there is real desire for change among our communities and the local authorities that serve them.

These ambitions are just a few of the drivers behind our Sustainable Energy Partnership with Coventry City Council, and our work with cities such as Berlin, Malmo and Milan – working in and with cities on solutions that work best with the people and the cities themselves.

Some of the latest ground-breaking innovations in sustainable energy are not only reducing greenhouse gases but also eliminating energy waste by turning it into a resource for clean energy – and there are some amazing, and slightly odd examples.

What do a Swedish ice cream factory, a hockey rink and a data centre in East London have in common? They are all exciting urban projects that prove the concept of “think global, act local” and are turning waste into sustainable energy.

Running your car on food scraps

In Stockholm, some Swedes are clearing their dinner plates and saving the scraps for a local biogas plant.

The Högbytorp recycling plant, takes leftover food and converts it into vehicle-grade biomethane which is distributed to vehicle refuelling stations for natural gas.

A typical household bag of food waste creates enough biomethane to drive a normal car for 2.5km. Any food that can’t be used is turned into biofertiliser so the Högbytorp plant tackles the growing problem of food waste too. The circular economy model encourages the continual use of resources by feeding them back into the system.

Warming homes with an ice hockey rink

In urban areas, heating is the biggest source of greenhouse gas emissions, and in the Swedish city of Örebro, E.ON and local leaders decided something could be done about this at a local hockey rink. Infrared mapping in the winter revealed the hockey arena was pumping huge amounts of waste heat into the air – waste heat that could be recycled and used as clean energy.

Thanks to an innovative district heating system, that waste heat is now being used to warm local homes and businesses nearby. Additionally, the rink’s cooling machines also run 25% more efficiently than before, reducing the facility’s operating costs overall.

Data centres, Tube tunnels or industrial processes

Data centres are the brains of the internet – so perhaps it’s no surprise that their processors are major energy consumers generating enormous amounts of waste heat. As the demand for faster and more complex computing grows, so does their energy consumption, making data centres the kind of urban sites where sustainable development is urgently needed.

At our new ectogrid development at Silvertown in East London, we are well equipped to make best use of waste heat from data centres – and the same goes for energy from Underground railway tunnels, industrial processes and other heat sources. These waste heat sources can be captured and used in this cutting edge heat network that will ultimately serve around 6,000 homes as well as business and leisure facilities.

Waste not want not

E.ON’s district heating scheme in the Lower Don Valley is powered by our Blackburn Meadows renewable energy plant which is powered by waste wood that would otherwise go to landfill. So those old wardrobes and pallets can be put to good use as a  source of heating to connected buildings in the Lower Don Valley and as electricity in the grid. We’ve recently unveiled plans to invest in an expanded Don Valley heat network which would mean more buildings across the area benefiting from renewable heating sources.

Sick dogs and ice cream

Sustainable technology can turn buildings into ‘living’ organisms – allowing them to share thermal energy flows between each other. Named after ectothermic animals like snakes and lizards which control their own body temperature, E.ON’s ectogrid™ is an energy solution connecting buildings and neighbours to use, reuse and balance their residual thermal energy to make sure as little as possible goes to waste.

One example is the animal hospital that scoops its heat supply from ice cream. In Slöinge, Sweden, streams of excess heat from the SIA Glass ice-cream producer are used at the Hallands Djursjukhus animal hospital, instead of being ventilated into the air. The project is not only climate-friendly and energy-efficient; both businesses report lower energy costs as well.

From zero waste to zero carbon

We are only just scratching the surface of exploring waste as a resource for renewable energy. And there is no time like the present – by 2050, most of the world’s population is expected to reside in urban areas, meaning that aggressive urbanisation will make the need for sustainable cities even greater.