MEXICO CITY, Jan 31 (IPS) – Mexico is looking for to mitigate water shortages in a part of its intensive territory by resorting to seawater, by the growth of desalination crops. However this answer has exorbitant prices and vital environmental impacts.
Among the many benefits of those water remedy crops, Gabriela Muñoz, a researcher on the public college El Colegio de la Frontera Norte, highlighted the growth of water sources and the manufacturing of water for human consumption.
However in her dialog with IPS, she additionally underlined the disadvantages of those crops, reminiscent of excessive power necessities, aggravated if the power comes from fossil sources; excessive prices; and the technology of brine and wastewater.
For example the prices: one of many desalination crops authorised in 2014 by the Nationwide Water Fee (CONAGUA) within the northern state of Baja California price some 35 million {dollars} to course of 250 litres per second (l/s). One other plant with the identical capability, given remaining approval in October 2020 within the neighbouring state of Baja California Sur, would require an funding of greater than 55 million {dollars}.
In Mexico “there aren’t any laws relating to eliminate the brine. The commonest factor to do is to dump it on the seaside. We now have to watch out how we deal with the brine due to the toxicity to ecosystems. Neither is there put in capability to deal with all of the wastewater. For particular areas, desalination shouldn’t be the primary possibility,” mentioned Muñoz from the northern border metropolis of Tijuana.
Between 2012 and 2020, environmental authorities authorised a minimum of 120 desalination services, rejected six functions and one other 5 are beneath analysis, in line with knowledge obtained by IPS by public info requests. A lot of the new tasks are situated in three states with acute water shortages: the northwestern states of Baja California and Baja California Sur, and the southeastern state of Quintana Roo.
Nonetheless, in Mexico, the place greater than 400 such crops function, there was no analysis on their ecological results, as corroborated by IPS, apart from the research “Desalination of water”, printed in 2000 by the federal government’s Mexican Water Institute.
One primary desalination approach is thermal distillation, through which seawater is heated till it evaporates, the vapor condenses to kind freshwater, and the remaining liquid is discarded as concentrated brine.
One other is reverse osmosis, through which water is filtered after which pumped at excessive stress by skinny membranes that solely enable the liquid to move by and retain the salt.
International context
In 2019, the research “The State of Desalination and Brine Manufacturing: A International Outlook”, produced by the United Nations College Institute for Water, Atmosphere and Well being, based mostly in Ontario, Canada, warned of the rising technology of brine and its severe results on the atmosphere. The method of extracting brine, it estimated, accrued a complete of 142 million cubic metres (m3) of waste worldwide that 12 months.
There are 18,214 desalination crops world wide, with an put in capability of 89 million m3 per day, serving greater than 300 million individuals, in line with the most recent knowledge from the Worldwide Desalination Affiliation. For each litre of water desalinated, a litre of brine is produced.
These crops are a part of a development in direction of the introduction of this know-how in areas going through the specter of water stress or shortage.
Water availability in Mexico
Mexico, Latin America’s second largest economic system, has an space of 1.96 million sq. kilometres, 67 p.c of which is arid and semi-arid land.
In accordance with CONAGUA, water availability varies extensively on this nation of 129 million individuals, as it’s scarce within the north and plentiful within the south.
Of each 100 litres of rainfall, 72 return to the ambiance by evapotranspiration, 22 run off into rivers and streams, and 6 feed 653 aquifers, of which 108 had been overexploited, 32 had saline soils or brackish water, and 18 had seawater infiltration because of rising sea ranges and seepage into the water desk.
Though Mexico had a low nationwide water stress stage in 2017 – 19.5 p.c – its danger of water stress is excessive, in line with the Aqueduct platform, developed by the Aqueduct Alliance, made up of governments, corporations and foundations.
In reality, Mexico is the second most water-stressed nation within the Americas, after Chile. Water stress could possibly be an issue by 2040 from the centre to the north of the nation.
In the meantime, the acute northwest presents a medium-high danger of aquifer depletion and virtually all the Gulf of Mexico and the Caribbean Sea current a medium-high danger of drought, exactly the place a lot of the desalination crops are situated.
Aqueduct takes into consideration 13 indicators of water stress, reminiscent of groundwater availability and depletion.
Within the final 5 months, drought has worsened in Mexico – the third worst file of the century – a consequence of the local weather disaster, in line with knowledge from the Nationwide Meteorological Service.
In Mexico water use is intense, mirrored in its water footprint – the influence of human actions on water – of 1,978 m3/particular person per 12 months, in comparison with a worldwide common of 1,385.
Because of this, nationwide and regional authorities have set their sights on seawater, provided that Mexico is bordered by the Pacific Ocean to the west and the Atlantic Ocean to the east, and there are a complete of 150 municipalities with a shoreline, out of a complete of two,466, in line with the Nationwide Coverage on Mexico’s Seas and Coasts.
Scalable mannequin
This 12 months, Héctor Aviña, an instructional on the Engineering Analysis Institute of the Nationwide Autonomous College of Mexico, plans to scale up his prototype geothermal-powered desalination plant within the metropolis of Los Cabos, situated in Baja California Sur, some 1,650 kilometres northwest of Mexico Metropolis.
“I do not know whether it is the most suitable choice due to brine technology and properly exploitation, however it’s a good various. Many areas are already experiencing water stress. In these locations, desalination and seaside wells may help aquifers get better,” Aviña informed IPS from Mexico Metropolis.
The five hundred,000 greenback plan consists of upgrading a pilot plant from the present capability of 4 m3 per day to 40 m3 and, if doable, to 400 m3, in an initiative to be developed with the state-owned Mexican Centre for Innovation in Geothermal Power.
The venture will reap the benefits of close by sizzling water wells to acquire water and geothermal power.
With this know-how, the fee per m3 of water ranges from 0.8 to 1.3 {dollars}, in comparison with 0.6 to 1.00 {dollars} utilizing reverse osmosis.
The Nationwide Infrastructure Funding Settlement, signed between the federal authorities and members of the enterprise group in November 2020, contains the foundations for 4 desalination crops in Baja California, Baja California Sur and Sonora, with an funding of 643 million {dollars} and a capability of 650 l/s.
However Muñoz urged that earlier than turning to desalination, poor irrigation practices, leaks and ageing infrastructure must be addressed.
“Earlier than contemplating desalination, measures reminiscent of water saving, funding in inexperienced infrastructure, rainwater harvesting and the reuse of handled water must be a precedence. We should additionally evaluate the prices of constructing desalination crops versus alternate options,” she mentioned.
In 2014 Aviña designed a reverse osmosis mannequin geared up with photo voltaic panels and batteries, which has aggressive prices.
“In different areas, the supply of power should be reviewed. Mexico goes to have water issues, it’s a state of affairs that we must reside with. If we research it properly, if we handle it properly, desalination is an efficient various,” he argued.
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