What do empty cans have in common with vegetables grown in stone wool?

Deborah Kelly Spillane
August 13, 2021

If you’ve ever been to Denmark, you might have been surprised to see people picking up empty bottles and cans instead of putting them in the bin. This is one of the first learnings for newcomers living in Denmark: By returning bottles and cans to the deposit machine in the supermarket, they can be exchanged for cash. This is a classic example of the circular economy – a way to keep materials in use for as long as possible.

As we realise the irreversible damage our “take, make and waste” consumerist society is inflicting on our planet, calls for a stronger circular economy are growing ever louder. And they are being met in new and innovative ways across many different industries – from the way we build to the way we heat our homes in winter.

Before we get into some exciting examples of circular businesses, let’s take a look at exactly what it means and just why it is so important. At the time of writing, the vast majority of the world’s resources, including metals, plastics, wood, concrete, chemicals are used only once before they become waste. Circularity is philosophy that reduces this enormous waste by keeping materials in use for as long as possible to decrease our carbon footprint and the constant exploitation of our natural world. It is based on three principles:

  • Design out waste and pollution
  • Keep products and materials in use
  • Regenerate natural systems

Circle House – circularity in construction

Let’s look at some real life examples of this philosophy put into practice. Close to Aarhus, Denmark, a social housing project has been built to demonstrate circularity in construction. With the construction industry being responsible for one third of all waste created worldwide[1], this move towards circularity is much-needed.

This unique building is the first fully circular building of it’s kind and the construction of this revolutionising building meant brining together many different stakeholders to re-think the construction process and selecting the very best materials. The Circle House project shows that it is possible to overcome the challenges involved and it has started a much-needed discussion around circularity in construction. You can read more about Circle House here:

From waste to heat

In Denmark today, 64 percent of all Danish households[2] get their heating from district heating. In the small town of Vamdrup, a short drive from Aarhus, you’ll find another example of how local businesses and are working together to re-use waste heat. Here ROCKWOOL’s stone wool factory contributes excess heat from its cooling systems to the local district heating network. This is then used to heat the homes of 1,500 local residents.

By turning what is often seen as a waste product into heat, local homeowners save 10 percent of their heating bills. At the same time, ROCKWOOL reduces the energy needed for cooling. And ultimately by reducing the need to heat and cool, everybody benefits from the reduced CO2 emissions.

Grown in stone

But circularity is about more than just building and recycling bottles – and it can be found at the cutting-edge of new, innovative methods of growing our food. If you’ve had a fresh salad lately, it might have come from a ‘hydroponic’ farm. You can think of these farms as high-tech green houses, many of which grows produce in highly controlled conditions using no soil. Instead these farms use soil substitutes, such as stone wool. It can be hard to wrap your head around the idea of growing fresh produce in stone  but this material is ideal for achieving more growth with less space and fewer resources.

In Denmark, the  indoor farm Katrine & Alfred grows tomatoes, cucumbers and chilis using Grodan stone wool blocks. The even density of the stone wool creates stable growing conditions and avoids many of the natural deviations that occur in soil. The exact amount of nutrients can be delivered straight to the plant, which results in less environmental impact and a more uniform product.

What’s more, this controlled method of farming lets the company save on fertilisers, and enables them to recycle and reuse water. In fact, growing one kilo of tomatoes in a state-of-the-art greenhouse using hydroponics takes only four liters of water whereas soil-based growing would require 60 litres[3]. That’s something that can only make your salad taste even better!

It’s time for circular thinking

Faced with an ever-shrinking window of time where we can take action to reduce our impact on the planet, redefining growth and industrial practices has become more urgent than ever before. Whether it’s building homes with less environmental impact, reusing waste heat or just recycling our empty bottles, circularity provides ways to rebalance our lifestyles that we need to embrace.

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