Desalination in Chennai - What about the poor and environment
Gregor Meerganz von Medeazza
In 1961, US president John F Kennedy noted that if humanity could find an inexpensive way to get fresh water from the oceans, that achievement would dwarf any other scientific accomplishment. Desalination technology embodies this hope, and has been increasingly perceived over the past 30 years as a feasible solution to meet growing freshwater demands. Reverse osmosis (RO) technologies in particular are increasingly popular. Daily production capacity in the 17,350 desalination plants operating worldwide has grown to 37 million cubic metres, supplying about 160 million people. However, the desalination technology is adopted primarily in the water-poor and energy-rich nations of the Persian-Arabian Gulf, where it accounts for 40 per cent of the municipal and industrial water used.
The Tamil Nadu government has called for the construction of a 100 million litres per day (MLD) seawater desalination plant to tackle Chennai’s mounting water crisis. The tender for a 25-year deal was signed in September 2005 and the Chennai Metro Water Supply and Sewage Board (so-called Metrowater) is contemplating setting up a further 50 or 100 MLD plant in the south of the city to supply the increasing needs of the IT industry. In December 2005, the first workshop of the Chennai Water Forum was held at the Madras Institute of Development Studies to “understand desalination and its implications for Chennai”. The fact that this large capacity plant will be located in a poor country like India is very surprising, given its relative energy-intensiveness compared to conventional water supply means. Even more surprising is the fact that Chennai is reaching for this type of solution while receiving approximately 1,200 mm of rain annually (about 10 times more than the precipitation rates found in most places that use this technology). And, recalling Chennai’s recent disastrous floods, it is probably the first time that a workshop on desalination had almost to be cancelled due to an excess of water.
The main questions, however, remain unanswered:
What will be the environmental impact of the desalination option? Desalination is often praised as an alternative to fossil groundwater mining or overexploitation of coastal aquifers. In the case of Chennai this argument, however, does not hold as current over-pumping rates are not likely to stop: the desalination plant is designed to provide additional water not alternative water. If the desalination option aimed at restoring groundwater integrity and halting the plundering of the peri-urban population’s water resources, the matter would be significantly different. Under the present plan, the two major environmental impacts of desalination (energy and brine associated pollution) must also be considered carefully.
What will be the long-term effect of such brine pollution on Chennai’s coast? A close examinaton should be made of the discharge of around 100 MLD of brine that will take place at the Minjur site. Brine is an unavoidable by-product of desalination, most commonly discharged into the marine environment. The environmental implications of this highly concentrated salt solution (around 70,000 ppm) on local marine ecosystems have been debated for many years. However, it is now widely acknowledged that extensive brine discharge, as it constitutes a hypersaline layer that sinks towards the seabed due to its greater density, has the potential to heavily affect local marine biota. The United Nations Environment Programme (UNEP) recently stressed the gravity of the problem: “marine desertification” has become evident with the desalination activity along the Gulf coastline. Furthermore, during pre- and post-treatment processes, a variety of chemical agents are added to enhance flocculation, prevent foaming or to avoid membrane deterioration. Resulting eutrophication, pH value variations, accumulation of heavy metals and disinfectants have pronounced effects on receiving waters.
Notwithstanding, a number of easily available brine remediation methods exist. Brine effluents must and can be prevented from entering into contact with sensitive ecosystems through proper site selection, construction planning, process design and discharge devices that would reduce salinity. The latter can be achieved through appropriate mixing and dilution. Sensitive ecosystems should be identified and the facility should be sited at an appropriate distance from the outlet source to allow sufficient dilution under various hydrodynamic conditions.
It has been recommended that brine discharges should be regarded as industrial waste requiring standardised treatment before discharge but according to current economic calculus, untreated sea-dumping seems the most cost-effective way to discharge the produced brine. This calculus might well change, if valuable ecosystem loss (in terms of environmental-service pricing) is to be accounted for.
Where will the additionally required energy come from and what will be its associated environmental impact? Nowadays, energy use for seawater desalination is in the range of 3 to 20 kWh/m3, with the older distillation plants at the top end. However, since the operational pressure to force seawater through the membrane remains around 70-75 bars, desalination is still a fairly energy intensive and expensive way of supplying freshwater. As a comparison, 6 kwh are required to lift one cubic metre of water by 1,800 metres, i e, higher than any bulk of water transfer currently undertaken worldwide. The environmental impacts arising from those energy requirements are dependent on the energy source used to provide the necessary pressure. Thus the major drawback of the desalination technology is that presently most of its energy is derived from fossil fuel burning.
Also, in the case of Chennai, coal is the main energy driver. The desalination process will, therefore be responsible for large additional amounts of greenhouse gas emissions. Moreover, as India seems to have embarked on a nuclear trend, this “carbon dioxide (CO2) for water” syndrome may well turn into “nuclear waste for water”. In Chennai, no scope is given to ensure the additional energy requirements to be covered by renewables. Hybrid systems (desalination-wind power, for instance) offer, however, attractive solutions both economically and environmentally. Instead, the production of 100 MLD desalinated water will generate over 30,000 tonnes of CO2 and around half a tonne of nuclear waste each year.
Furthermore, relying on an energy- intensive production process for the provision of vital freshwater, in a system that is tending towards exhaustion of cheap energy sources, is not a sustainable solution. Indeed, with the probable decrease in cheap energy resources, desalination technologies, like other energy-intensive water supply systems, may fail to fulfil their long-term expectations.
Who will bear the cost of the water produced? Internationally, much attention is given to the “polluter pays” principle as well as “full cost recovery”. What would be the real cost of the desalinated water if environmental externalities (due to brine pollution or greenhouse gas emissions) were internalised? These issues are not being discussed in the case of Chennai’s new desalination plant. Price and income effects usually explain water demand. Income and price elasticities of water demand are generally high, but rapidly drop to zero when serving drinking purposes, i e, basic human needs. “Water for the poor” is, therefore, a very sensitive issue, as willingness to pay for survival may tend towards infinity.
Is desalination to be considered as a sustainable water management option? The water crisis in Chennai is the consequence of growth in both population and consumption, combined with declining natural water resource stocks mainly due to pollution and unsustainable resource exploitation. There are two possible approaches to water management. On the one hand, the traditional, supply-driven approach focuses predominantly on providing water by large-scale hydraulic engineering works such as damming, transfers, desalination, pumping, etc. On the other hand, demand management is implemented by measures such as changing the tariff structure or resource conservation. The second approach rests on the three pillars of sustainability – economic (“full cost recovery” principle), social (proactive “public participation”) and environmental (restoring “good ecological status” of rivers). In the last few years, these principles have triumphed in water economics (at least in theory) over the old strategy of increasing water supply.
The principle of “dominating nature’ that led Chennai to a supply-oriented water management approach results in a ‘hydraulic structuralism” strongly rooted in engineering and technical sciences. For example, Metrowater supplies water partly by groundwater (over-)pumping, and partly from a plethora of large-scale hydraulic works. The long unquestioned success of the hydraulic structuralism approach has produced the impression that water scarcity problems can (and must) be entirely solved by increasing supplies. The traditional water culture of prudence has been slowly eroded as temple tanks and other water conservation facilities were neglected. The desalination option is well inscribed in this hydraulic structuralism and supply-driven logic. However, as Say’s Law states “supply creates its own demand, which will exhaust supply”. Instead of these supply-side approaches, demand management schemes as well as restoration and conservation strategies (where the insufficient polluter-pays principle should be replaced by the principle of no-deterioration at source) should be implemented within an integrated hydrological basin management approach.
What are the (missed) alternatives? Chennai’s water expert community argues that if the ancient and neglected urban and peri-urban tanks, ponds and lakes were refurbished to allow for sound rainwater harvesting to occur, the city would obtain more water than it daily requires. Also, the huge re-use potential offered by treated wastewater has not been properly explored. Finally, no real effort seems to have been made to reduce water losses in the city’s pipelines.
Even the World Bank seems to agree that desalination should remain a solution of last resort, adopted only after appropriate water demand management measures have been implemented. Ultimately, saving and harvesting water rather than developing new supplies is often the best “next” source of water, both from environmental and economic perspectives. Not only would these cost a mere fraction of the Rs 500 crore that the plant will cost, but they would also contribute to long-term resource conservation through recharge. Desalination is a (hard) technological fix that locks Chennai’s water management into an ever increasing supply syndrome while locking out other (softer and sounder) technological options.
What scarcity are we talking about? The issue of metrowater’s technological approach raises questions about how scarcity is perceived in the context of Chennai. On the one hand, there is the question of levels of scarcity (related to human need). Here, water services for the booming IT and automobile industries contrast dramatically with the water scarcity experienced by the urban poor.
There is also the question of scarcity type. Considering Chennai’s precipitation rates, one wonders how much Chennai’s so-called water “crisis” is of a physical order, or primarily a mismanagement-triggered scarcity. It is the human demand, but also the mismanagement of available water in a given region that eventually turns a physical scarcity (of climatologic and territorial origin) into a social one, experienced by the local population.
The notion of “water scarcity” can also be differentiated by the concepts of basic need and socially constructed need which can be called want. For instance, scarcity below 20 or 30 litres per person/day is an absolute level of scarcity where health problems such as cholera may appear. Most slum dwellers in Chennai experience this type of scarcity. It should be emphasised that water policies cannot be analysed separately from water needs (and uses). Desalination might be effective in alleviating a physical scarcity by producing required quantities of water. It should not be dismissed as a “last resort” option if it can provide a solution for livelihood needs and public health. But in Chennai’s case, it is unlikely to provide a sustainable solution to the crisis, which is essentially due to failed governance, i e, triggered by resource mismanagement and lack of stakeholder participation.
Who will this desalinated water (not) benefit? Given that one-third of Chennai’s population lives in slums, with very limited water access, an approach based on “basic needs” is indispensable. Most of Chennai’s slums are unconnected to the city’s main water and sanitation grid; they are, therefore, likely to be bypassed by the proposed desalinated water which will be distributed through the existing piped network. However, currently two slums in Chennai have part of their water needs covered by small desalination plants, supplying water through an autonomous grid. These systems seem to offer a good illustration of “desalination serving basic needs”. The crucial questions then, are: will the additional water provided by the new costly plant benefit those who most need increased access to freshwater? Will it reduce the immense pressure put on peri-urban aquifers? Focusing on these issues will cast light on the purpose served by desalination. The energy-intensiveness and other drawbacks of this technology are particularly problematic from an ethical standpoint if they do not help to maintain livelihoods, provide cheap water to the poor and reduce the environmental pressure on peri-urban areas. Indeed, if the new desalination plant fails to meet these objectives, then Chennai’s traditional water patrimony, its cultural water memory (embedded in the neglected temple tanks, for instance) and social integrity are being dismissed while environmental degradation, economic volatility and technological “lock-in” are engendered for the sake of sustaining non-livelihood, non-vital uses, i e, falling into the “luxury” category. Under the current plan, desalination mainly feeds the increasing supply ideology rooted in the prevailing economic growth paradigm. It is, indeed, more likely to allow those whose basic water needs are already covered to increase well-established consumption patterns of both water and energy.
Desalination for the Poor: Towards an Equitable Use of the Technology The proposed desalination plant is a dangerous solution to Chennai’s current water crisis for at least six reasons: (1) This energy-intensive technology is responsible for greenhouse gas emissions, producing environmental costs which are uncovered or are unloaded onto the energy sector. Similarly, negative environmental impacts arising from uncontrolled brine discharges are also externalised. (2) The desalination option is still very much a supply-oriented strategy which will only stimulate more demand. (3) It threatens the traditional water-saving culture, creating a false impression of abundance. (4) Current environmentally damaging water exploitation practices are not likely to be altered, and the desalination option is therefore unlikely to solve the peri-urban conundrum. (5) Due to the “lock-in” nature of this technological fix, long suggested alternatives are unlikely to be implemented. It will encourage social and environmental dumping. (6) Finally, if full-cost recovery is attempted for this expensive project, the poor would not be able to bear the costs or would be deprived even further. Ultimately, the issue this paper would like to raise is the purpose served by this new desalination plant and whom it will primarily (not) benefit. “Desalination for the poor” should become the buzzword. Beyond technological choice or even technological change, the focus should be on technological equity as a cornerstone for debate. Providing water to those who currently do not have access to it and therefore need it most, should become a chief concern.
Source : EPW, March 18