Whether water or energy, quality matters

Published Tuesday, March 1, 2016 in the New Brunswick Telegraph Journal and the Fredericton Daily Gleaner.

Here’s a quick quiz: if your shower consumes 120 litres each day, toothbrushing and hand washing require 30 litres and your toilet uses 150 litres, how much water do you need to operate your bathroom each day?

Careful – it’s not quite as straightforward as it may seem.

Water quality

When it comes to water, most people know that there’s a broad range of qualities, from pure and pristine to stagnant and dirty.

And when it comes to end uses, there’s a broad range of quality needs.  For example, drinking, cooking and bathing require the very best water – but a far lesser quality is perfectly fine for uses like watering lawns or flushing toilets. 

In developed countries like Canada, we’ve constructed water supply systems that have us using top quality water for every end use, from drinking to flushing toilets.  That means the typical washroom with the above consumption figures would use 300 litres of top quality water every day.

But that same washroom could operate on half that amount if only we matched water quality availability with water quality needs.

In other words, if the used water from showering, toothbrushing and hand washing – commonly referred to as greywater – were kept and used for toilet flushing, the washroom would use only 150 litres each day.  That represents huge savings.  

Greywater capture and re-use is common in places where water is scarce, such as Africa and the Middle East.  In a similar vein, some of NB’s most progressive new buildings capture rainwater and use it for landscaping (medium quality) or flushing (low-quality).

If precise matching of water quality availability to water quality needs is an effective formula for saving water, it’s a great model for something even bigger.

Energy quality

Few of us pause to think about it, but, like water, energy comes in a full range of qualities.  

Of commonly used energy sources, electricity is at the top end of the quality scale.  You can do almost anything with it.  

Next would be oil, which offers lots of energy per unit of weight in convenient liquid form.

Then coal – quite energy dense, but more cumbersome to handle than oil.  Then wood and other biofuels.

And toward the low end would be warm water and warm air.  They contain energy, but it’s of limited use.  That’s why the waste heat and hot water that are by-products of many industrial processes are usually dispersed into the environment.

Energy quality requirements

Few of us pause to think about it, but, like our water requirements, our energy requirements follow a quality gradient.

Appliances, computers, lights and pumps require high-quality energy, and the logical match is electricity.

But domestic hot water and warm air – which together account for three-quarters of the energy consumed by a typical home – are on the opposite end of the spectrum.  They’re low-quality energy requirements, because just about any energy source can heat water or air.

Yet, in New Brunswick, electricity is habitually used to produce hot water and heat.  It’s like using your fanciest china to feed the dog. 

The bottom line

If we NBers were to use lower quality energy sources – whether solar, wood, geothermal (all readily available in NB) or some other – for our heating and hot water, and then reserved our high-quality electricity for our lights, computers and appliances, we’d take a huge load off of our power grid and virtually eliminate those expensive winter load peaks.  As well, since a lot of our power is fossil fuel-generated, we’d take a huge bite out of provincial emissions.

Moving in that direction won’t happen overnight, and it would come with challenges.  But perhaps it’s worth contemplating as our province strives for greater economic self-sufficiency and lower greenhouse gas emissions.