The hidden power of your toilet flush

Friday, 22 June, 2018

By Mads Warming, Global Lead, Water & Wastewater, Danfoss Drives

Picture this – the energy needed to get drinking water on the tap and treat wastewater comes from the toilet flush. On the verge of facing a water crisis and handling a high energy consuming water sector, we must be ambitious. We must start thinking about smarter, more innovative and inclusive ways to manage our water. The solutions that can protect our precious water resources and turn the water sector energy neutral are available.

A water crisis ahead of us

The World Economic Forum lists a water crisis amongst one of the five global risks that will potentially have the largest impact on the well-being of people and economic growth in the next decade.

In some places around the globe, water is already being heavily over drafted. This means that we are using a lot more water than nature is able to regenerate. If we keep up with this rhythm, by 2030, 40% of the global population will live in water scarcity areas.

We already know that the planet is 70% covered with water. The surprising fact is that only 0,6 % is available as freshwater. That is, only 0,6% is fit to drink and be used to produce food and energy. And it isn´t even split evenly around the globe. So, we have a water challenge. And this is why we must start dealing with water more efficiently.

Water leakage – a homemade issue

Whilst parts of the water crisis are caused by climate change and overconsumption, some issues are homemade. An important factor affecting our drinking water supply is water loss through leakages.

How can we accept, while facing water scarcity in some places, to lose 30% of water because of leaky pipes around the globe? The highest figure reported is 80% loss. This is not only a waste of good water but also of energy. We must limit water leakages in order to reduce energy usage and save water.

Utilities often rely on old piping systems but also on poor water pressure management. Unnecessary high pressure across drinking water supply systems stresses and wears out the pipes, creating leakages and increasing maintenance costs. This unnecessary high pressure in the pipes means that also an avoidable high amount of water is pushed out of the leaks. We´re just losing a lot of water and energy.  

By introducing intelligent pressure management, we can reduce pressure by 38% and minimize leakages. With this technology, we split the city into pressure zones. Pressure sensors and variable speed drives are the key components and allow to pump water according to the needs of each pressure zone. This way we reduce water loss by 40% and energy consumption by 20-40%.

Bottom line is - we can limit leakages without digging up a whole city to replace entire pipe systems. But there is room to be more ambitious about the way we manage water. The good news is we can minimize water leakages and protect our precious water resources, but also turn the water sector energy neutral.

From energy consumer to energy neutral

Did you know that every time you flush your toilet, it takes a lot of energy to treat and clean the wastewater? According to the International Energy Agency, water and wastewater facilities account for around 4% of global electricity consumption – around seven times of all electricity used in Ukraine.
Plus, 30-50% of your local authority’s electricity bill is spent on the water sector.

Because of the major load variations, real-time automatic process controls have the capability to lead to amazing energy savings. By optimizing existing facilities, and introducing sensors, and variable speed drives, water, and wastewater facilities can run at a rhythm adapted to the water load.

This is what we call digitalization – and it can offer both energy savings and increased energy production from your toilet flush. In fact, wastewater facilities can produce more than enough energy to cover the wastewater treatment process and beyond.  

How? The energy is contained in the sludge - a by-product of the wastewater treatment process - and can be recovered as biogas. The biogas can then be used to serve the energy needs of the water and wastewater treatment process. The surplus energy produced can be used to provide drinking water or even heat up our homes. 

The future is here

Turning a city’s largest energy consumer into a producer of energy is a game changer and it has been done. Today, the city of Aarhus, which shelters 200 000 inhabitants, has succeeded to make the whole of its water cycle energy neutral. As side effects, water losses have been reduced to around 6%, and, in 2016, the price of water dropped by 9% for consumers.

This is replicable to existing facilities. Achieving energy neutrality of the water cycle has a payback time of typically 2-5 years and results in improvements at a rate of approximately 70%.

So, the next time you flush your toilet, remember its hidden power. We are Engineering a highly intensive water sector into an energy-neutral party. These best-available technologies can make the whole water cycle significantly more energy efficient, help cities reduce water needs and thus meet their ambitious sustainability targets.

Help to spread the word on smart #WaterManagement and #EnergyNeutrality and contribute to creating global best practice solutions.


Watch the #ETtalks presentation on Smart Water Infrastructure