There’s a lot of water involved in the production of energy. And a lot of power is required for the treatment of (waste)water!

Hence this concept of the Water-Energy Nexus.

But beyond the term, what’s in it for the Water Industry? How can we help? And how can it feed our growth? Let’s review ⬇️

What is the Water-Energy Nexus?

Water is heavily involved in the production of energy. Of course, especially when it comes to electricity – think of all the steam a nuclear or thermal power plant requires, but also as hydropower. And there’s also water involved in shale gas fracking, oil, and gas processes!

On the other hand, 4-8% of the world’s electricity is spent on water and wastewater treatment but also pumping. You have to add to that all the power needed to heat or cool water – even though out of my scope for today. There’s also an interesting relationship between power supply needs to the Water Industry and Resource Scarcity: in California, the 4-8% consumption figure rises to… 19%!

So this Water-Energy Nexus term is the encapsulation of this interconnection.

Without access to a power supply, there’s no desalination. And without water, there’s hardly an electricity source. Which is of course intricate and challenging, but also an opportunity!

How is Water involved in the production of Electricity?

Thermoelectric production relies on heating water resources, transforming them into steam to power a turbine that in turn produces energy.

To give you a sense of magnitude, Wind Turbines represent 5.3% of the world’s electricity as of 2020, Solar a further 2.7% and other renewables 2.5%.

All the remaining 89.5% involve Water! Whether directly, with Hydropower representing 15.8%, or indirectly in the case of Oil, Coal, Gas and Nuclear I already mentioned.

Last staple in my point: how do you produce a Solar Wafer or a Wind Turbine without water? Simple: you don’t 😉

Could the production of Hydrogen become a major Water Application?

So we’ve seen that water can be a tool within the production of electricity. But what if we turned that idea on its head, and used electricity to split water into hydrogen and oxygen?

That’s the full Idea of Green Hydrogen production (oxygen is a by-product there), leveraging renewable energies to power an electrolysis process.

Green Hydrogen is often referred to as a tool in the decarbonization of our World. It may power a portion of our future transport means (cars, trucks, buses, ships, planes…), and be used as an energy carrier in many industrial applications, and even up to our homes – if we were to switch from methane to hydrogen.

Now, that’s also a tool with limits of its own: electrolysis is a complex and energy-intensive process, which in turn involves that it is expensive. And the entire application is sometimes looked up weirdly by the water industry, concerned that it may gobble gargantuan amounts of water.

And after all, is the concept of burning a low-density energy carrier like hydrogen even any good? That’s a hot topic, and I thought it deserved a deeper dive, so have a look here.

You’ll also get to discover an additional color of Hydrogen that’s of interest for the Water Industry: Turquoise. Because how cool would it be, if it enabled to turn wastewater treatment processes into negative carbon applications?

How much power do we need to treat wastewater?

Wastewater Treatment alone accounts for 3 to 5% of the Global Electricity Consumption. This equals to about 1’000 Tera Watt Hour of electricity every year. Again, for a sense of magnitude, that’s the production of 200 nuclear power reactors!

If we consider that the World treats about half of its wastewater today, that means that this value will go up. When we will meet the United Nation’s Sustainable Development Goal number six, we will need twice much electricity to treat wastewater.

And the World’s population is still growing: there will be 3 billion more humans on this Planet by 2050.

At that growth rate, we will require about 520 nuclear power reactors in 2050 only for our wastewater treatment plants to work.
That’s more than there are in existence in the World, even if we factor in the ones currently planned.

How can we turn wastewater into a renewable energy resource?

That’s the beauty of it: yes we do!
That’s also why we should stop calling it a waste. It’s not wastewater, it’s liquid energy!

To determine the size of what we’re discussing here, we need a proxy: the Chemical Oxygen Demand (COD) of sewage.

On average, every human on earth produces about 60-120 grams of COD daily. Remember, we will be 10 billion humans by 2050, so that makes one million tons of chemical oxygen demand every day.

In two studies, Elisabeth Heidrich determined the relationship between the energy content of municipal sewage and COD: it’s 16.1 kJ/gCOD

If we do the maths, that’s 4’472 gigawatt-hour of energy every day – about 1’600 Terawatt-hour per year.

To give you a full view. that’s about:

  • 320 nuclear power reactors.
  • 140 million tons of oil being burned in thermic power plants.
  • 32’000 of the World’s largest capacity wind turbines.

… And of course, it’s fully renewable! Wanna know more? I’ve explored it in this deep dive.

What about Food?

To get the total view, many people usually add Food into the nexus. That framework is perfectly right, so I’ll try to expand this study in the close future to give everyone a full overview – I hope you considered this page a living document (I’d be happy to see you back soon 😉)

Because let’s face it, to strive in this nexus, it will require new management approaches to have an impact!