Over a decade, ef?ciency gains in reverse osmosis plants resulted in a 33 per cent drop in electricity consumption for water production, the NSO said.

This year’s World Water Day seeks to raise awareness of the inter-linkages between water and energy.

The inter-linkages between water and energy in Malta include both the production of electricity, which is dependent on the provision of cooling water from marine sources, and the production of public and irrigation water by means of electrical power. This release focuses on the production of public water from groundwater sources and reverse osmosis plants, and the production of irrigation water from wastewater treatment at the Sant’ Antnin plant.

The production of public water by the Water Services Corporation (WSC) averaged 30.6 million cubic metres per year between 2004 and 2013. Furthermore, 44.3 per cent of all public water originated from groundwater sources, while 55.7 per cent was produced at the three reverse osmosis plants which the corporation operates.

Data on treated wastewater shows that over the past decade the Sant’ Antnin plant processed an annual average of 2.1 million cubic metres of wastewater. Additionally, 63.6 per cent of all water treated at this plant was mainly used for irrigation in the surrounding agricultural areas. The total amount of wastewater treated by this plant has seen a gradual decline, from 3.1 million cubic metres in 2005 to 1.7 million cubic metres in 2012. This was mainly due to a reduction in the demand for irrigation water produced by this plant.

During the period under review, the average power required to produce one cubic metre of water from reverse osmosis plants amounted to 4.6 kilowatt hours, considerably higher when compared to the average power required to extract groundwater, which stood at 0.8 kilowatt hours. Irrigation water produced from the Sant’ Antnin plant averaged 1.3 kilowatt hours per cubic metre.

Over the past ten years, the average energy consumed for producing water from groundwater, reverse osmosis plants and wastewater treatment at the Sant’ Antnin plant amounted to 4.4 per cent of the total electricity supply for Malta. Reverse osmosis operations are by far the largest electricity consumers from all three water sources. From 2004 to 2013 ef?ciency gains in the operations of WSC resulted in a decrease of 33.2 per cent in the electricity consumed by reverse osmosis plants. This brought down the share of electricity consumption from the total electricity supply from 4.8 per cent in 2004 to 3.2 per cent in 2013.