Efficient use of water is vital for our operations, environment and local communities in the proximity of which we operate.
There are two main types of water use in our operations: 1) desalination for which our Water segment assets withdraw sea water and 2) power generation for which our Renewable sector assets withdraw fresh water from rivers, aquifers and other freshwater sources.
Note: (1) Does not include ACT steam generation as water is provided by PEMEX
In 2017, we withdrew 227.2 million cubic meters of water of which 95% was sea water. We discharged 120.4 million cubic meters, of which 117.0 million cubic meters or 98% was returned back to sea. In 2016, we withdrew 224.7 million cubic meters of water, of which 95% was sea water and discharged 117.5 million cubic meters of which 114.9 million cubic meters or 98% was returned to sea.
Some of our assets have a progressive technology with limited water consumption, as for example our solar plant located in the arid area in the Kalahari Desert in South Africa. This technology allows our plant to consume approximately 1/3 of water of a comparable size solar plant of previous generation. Additionally, we are implementing efforts in collection, recycle and use of rain water to reduce our consumption in some of our solar facilities in Spain. The collections of rain water are immaterial to our operations however we continually search for ways to minimize our impact on the environment and use of water
Some parts of the world suffer from current drought conditions which, combined with a water supply that is unfit for human consumption, can foster disease and death. Scarcity of water also results in reduced availability for food production. Sea water desalination can provide a climate-independent source of drinking water.
Our Water segment includes two desalination plants. They withdraw sea water for desalination purposes as specified in their concession agreements. Thus, in 2017, we withdraw 216.6 million cubic meters of sea water which went through the desalination process of removal of salt and minerals in water treatment facilities to prepare it for human use. We returned 117.7 million cubic meters, or 54% back to the sea. In 2016, we withdrew 213.2 million cubic meters and returned 114.9 million cubic meters, 54% back to the sea. The difference between water withdrawn from and returned to the sea is the desalinated potable water delivered to the water utility, as specified by our take-or-pay concession agreements for consumption needs of 1.5 million people.
Renewable segment is another part of our business that utilizes water in its power generation. We primarily use water for cooling of condensers during power generation in our facilities. The fresh water is primarily drawn from rivers and aquifers. We hold permits to withdraw water from these sources and adhere to regulations on water quality. The difference between water withdrawn from and returned to its source is our water consumption which occurs largely due to evaporation.
The amount of water we withdraw, and return is measured by the installed water meters at the pumping equipment of the plants. The reported volumes represent the total readings measured by the water meters of all our assets without adjusting for our interest in the assets. The water meters are sealed and are normally subject to audit by the inspector representing the local water authorities. We have met the requirements and regulations of the applicable local regulatory authorities in geographies in which we operate. We report the results of our water statistics to local water agencies on a periodic basis.
In 2017, we withdrew 10.6 million cubic meters of fresh water at our power generation plants and we returned 2.6 million cubic meters, or 24% back to the source. In 2016, we withdrew 11.5 million cubic meters of fresh water and returned 2.6 million cubic meters, or 23% back to the source. The water returned to the environment is tested by independent external laboratories on a period basis to ensure its quality.
Our efforts to improve our water management beyond compliance is a main factor behind the reduction of withdrawal volumes in 2017 compared to 2016. We implemented better practices for use of water in operation and maintenance of our solar plants, such as adjustments in the operating cycles of the water cooling towers. In 2017, we withdrew 10.6 million cubic meters which represented 49% of the limits allowed by our water permits. In 2016, we withdrew 11.5 million cubic meters which represented 53% of the limits allowed by our water permits. The difference between the water permit limits and actual water withdrawn represents water savings.