DRIVES, MOTORS + SWITCHGEAR
Making the case for an energy-neutral water sector
Expanding water treatment globally is not only a key enabler for creating a better world for humankind, it can also contribute to combatting climate change and reducing carbon dioxide and greenhouse gas emissions. And digitalisation, intelligent automation and efficient drives can play a central role.This was the perspective presented by Mads Warming, Global Head:Water & Wastewater, Danfoss Drives, speaking at the 11th annual Sustainability Summit held as a live virtual event in South Africa last year.
Mads Warming, Danfoss Drives.
W arming said that currently, only about 20% of all wastewater globally is treated, which means around six billion people have access only to un- treated water. The United Nations (UN) Sustainable Development Goal (SDG) 6 defines improvement targets for clean water and sanitation. SDG 6.2 sets the objective of improving the pro- portion of wastewater treated globally from 20% to 60%, by 2030. Achieving this objective would bring with it a multitude of health improvements, and would play an important role in reducing the greenhouse gas (GHG) load. Typically, the key components in water treatment emis- sions are methane (CH 4 ), nitrous oxide (N 2 O) and carbon dioxide (CO 2 ). CO 2 results from the energy consumed, and the term ‘greenhouse gases’ encompasses all three com- ponents. Warming highlighted that: “Perhaps unexpectedly for many, the GHG effect of letting the wastewater escape un- treated into the surrounding environment is far more detri- mental than that of additional energy consumption resulting from new wastewater facilities.” According to the International Water Association (IWA), untreated wastewater running directly into the environment
generates a GHG footprint roughly three times higher than when the same wastewater is dealt with in a traditional wastewater facility. “The good news is we already have the right technology needed to move forward to achieve energy neutrality, and an additional one-third reduction in GHG emissions can be gained by using digitalisation and applying variable speed drive (VSD) control,” Warming said. “Furthermore, VSDs are playing a critical role in helping the water sector to reduce energy usage. And there is an excellent reason for this, as water and wastewater facilities are extremely energy intensive. The International Energy Agency (IEA) states that four percent of all electricity used globally goes towards water and wastewater handling fa- cilities alone. The IEA also says between 30 and 50 % of the electricity bill of a local government authority is typically related to these operations.” The world’s first energy-neutral catchment area With assistance from Danfoss, Aarhus Water, the second largest water service company in Denmark, has succeed- ed in bringing the entire water cycle (drinking water and wastewater) in a local catchment area into energy neutrality. Aarhus Water’s aim was to transform the water treatment facility of a catchment area in the centre of Aarhus – a small borough called Marselisborg, with a population of 200 000 people – into an energy producer, at the same time achiev- ing energy neutrality for the drinking water supply, waste- water pumping and wastewater treatment. Marselisborg is a traditional city area in a relatively flat geographic region, where water supply is based on ground- water, which is on average pumped from 35 m depths, and traditional household wastewater treatment. It has become the world’s first energy-neutral catchment area. The approach adopted by the utility and Danfoss was based on a two-step strategy: Reducing energy consumption throughout the water and wastewater facilities to the lowest possible sen- sible level, and Increasing energy production from the wastewater facility.
With assistance from Danfoss, Aarhus Water in Denmark transformed the water treatment facility of the Aarhus borough of Marselisborg to energy neutrality.
10 Electricity + Control MARCH 2022
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