The energy sector should care about wastewater

The energy sector should care about wastewater

About 4.5 billion people around the world still lack access to safely managed sanitation and 80% of the world’s wastewater is released untreated.

Two of the targets under the Sustainable Development Goal dedicated to water (SDG 6) — providing sanitation for all (target 6.2) and halving the proportion of untreated wastewater (target 6.3) — seek to address these challenges. But meeting these targets could put significant upward pressure on energy demand.

The links between energy and water run deep, which explains why the IEA is looking at the issue.  New analysis in this year’s World Energy Outlook (WEO) shows that today’s water sector, which includes the collection and treatment of wastewater, accounts for 4% of total global electricity consumption. Wastewater treatment alone represents roughly a quarter of the water sector’s electricity consumption. Additionally, some estimates have put the sector’s share of total greenhouse gas emissions at 3%. However, there are also significant opportunities to produce energy by harnessing the embedded energy in wastewater, as our analysis in 2016 emphasized.

The urban technology challenge

In urban areas, where almost 2.3 billion people still lack access to safely managed sanitation, this year’s WEO examinedthree potential pathways for urban municipal wastewater management to achieve sustainable development goals. They provide an illustration of how technology and policy choices can influence the additional electricity needed:

– If cities follow today’s typical technology blueprint for centralised wastewater capacity, electricity consumption could increase by over 680 TWh over the period to 2030.

– If cities instead deploy a range of economically viable energy efficiency technologies in all new wastewater facilities, as is done in our Sustainable Development Scenario (see left-hand side of the Figure below), the increase in electricity consumption could be reduced by roughly 10%. This pathway also sees higher rates of energy recovery; 30% of the electricity needed to meet the targets could be generated from the wastewater itself, compared to just 6% if the current blueprint for wastewater management is used.

– A third possibility, at the frontier of today’s technology, is to build energy-neutral or even energy-positive facilities (right-hand side of the Figure). On this pathway, electricity consumption would increase by less than 460 TWh thanks to additional energy-efficiency measures while the installation of energy recovery for biogas and high-efficiency combined heat and power units would enable utilities to generate over 50% more electricity than they need.

Source: International Energy Agency (IEA)

Date: December 2018

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