25 Jun 2014

Accounting for energy used to move and treat water

I made this schematic while in Saudi Arabia, to help my colleagues understand the flow of water through a system (from source to sink, even if that sink is a source) and thus how and where energy would be used in the system. This figure could be used to present aggregated data from numerous parts of the system (many of them running in parallel) to help managers and regulators understand the energy consumption of a system.

Here's the PDF

A few notes:
  • Leakages of water also mean leakages of energy, but they are missed if they are unbilled
  • This diagram does not include energy used by customers (e.g., heating water), which is significant
  • Energy usage varies with standards for treatment or sources of water. Vancouver gets gravity-delivered snowmelt while Riyadh depends on desalinated water piped from 500km away
  • Water and energy accounting does not lead to good management, but managers can use this information to improve efficiency

Please tell me if this is useful to you or missing any significant features.


BJ (via twitter) said...

Fig suggests all water is treated. Opposite is actually true-most water is conveyed to a use(r) directly from source w/o trmt

David Zetland said...

@BJ -- No. The figure "allows" for 0-100% treatment...

Jamie Workman said...

Any rough or mean number you know that estimates energy embedded in water at national or global scale? Like 1 kWh per 1000 liters?

Johannes said...

Hi David, I like the scale you used for the 3 components from left to right, going from low to high value: really insightful. Maybe you can highlight this gradient somewhat more in the graphic, by adding a gradient in colour f.e.

David Zetland said...

@Johannes -- Good idea. Done!
@Jamie -- as you know, it varies with source (desal v g/w), so what can you do with a national average?

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