Desalinated water manufactured in an ecofriendly manner as an option for Auroville.

The whole of the coast of Bengal is heading directly into an ecological disaster in terms of its water resources. In the area around Auroville the pumping of ground-water is about 17 times more than the natural recharge from rainfall. In the Auroville area it is 6.5 times. This is the alarming result of studies made by two French water scientists who have conducted researches in the Auroville area. The ground-water level is already below sea-level in many places; the Cuddalore Aquifer is collapsing; and the Vanoor aquifer is about to follow.

If we just keep watching and do not act, we will soon face having saline ground-water without any alternative water source available. Varuna is trying to set up a desalination plant at the beach near Bommaiyapalayam which will use green energy and a non-polluting process of operation. This alone cannot prevent ground-water salinity in the long run, but it can make a certain area independent from ground-water, and it can – depending on the size of the plant – be at least one measure which will counteract the encroaching salinity.

Our first aim is to set up a model plant which will demonstrate that:

a) It is possible and economically viable to manufacture fresh water from the sources which we already have.
b) It is possible and economically viable to manufacture fresh water from seawater using a non-polluting method which does not harm the environment.
c) It is well within the financial reach of small communities, villages or small towns to set up eco-friendly desalination plants and thus provide a solution, or at least an alternative, to the increasing salinity of their local ground-water.

Our second aim is, once the first model-plant is up and running, to help communities and villages along the coast to set up a replica of our plant, thus evading the present threatening situation and being able to find a water-management solution which is environmentally friendly and sustainable.

Our third aim is to provide Auroville and the whole area with an alternative water-source. This will make Auroville independent from ground-water and enable it to achieve its original vision of a town of 50,000 inhabitants.

The economics of a desalination plant are not so outrageous as one might think. The times when desalinated water was unaffordable are gone since long. To desalinate one cubic-metre of water today takes only around 2 kWh of electricity, and the technology is still advancing. One cubic metre of water is equivalent to the daily domestic water need of 5 Aurovilians, or if we include gardening, then of 3 Aurovilians. And 2 kWh is less than what one single Aurovilian uses daily in terms of energy. Today, just over 2,200 Aurovilians are consuming 8,800 kWh of electricity every day and 1,500 cubic metres of water. This includes all services, industries and agriculture. If the present Auroville would have to rely totally on desalinated water, and all the 1,500 cubic metres of water which Auroville presently consumes would be manufactured in a desalination-plant, then our daily electricity consumption would go up by 40% from 8,800 kWh per day to 11,800 kWh. With its 4 wind generators Auroville is producing today around 17,500 kWh of green energy. So it would be well within Auroville’s ability to supply all the water that Auroville needs and consumes from a desalination plant.

The initial costs of setting up a desalination plant are approximately 1,000 Euro per cubic metre of fresh water being produced per day. We are planning for the first phase to set up a plant which will produce 1,000 cubic metres of fresh water per day, which would meet 2/3 of Auroville’s total consumption needs. A plant to produce that will cost us 1 million Euro. If we look just at the domestic water for one single resident of Auroville, then we are talking about 200 litres per day. That is 0.05% of the cost of our plant, or 500 Euro. That means that if every Aurovilian would contribute 500 Euro, then with that money we could set up a desalination plant which could take care of 100% of his/her domestic water needs. However, with the needs of agriculture, gardening, industries and services added, each Aurovilian actually consumes on average 680 litres of water per day.

For Auroville and the whole area we see a desalination plant as a necessity without alternative. Harvested rainwater has many disadvantages in comparison with desalinated water. First of all you can only harvest it in adequate quantities during the monsoon, and then have to store it for up to 10 months until it is consumed. The storage costs are about 45 times what it costs to manufacture fresh water by desalination. Unfortunately, we can utilise our storage-capacity only once a year. All storage capacity will have to be filled during the main monsoon time, and will then be emptied during the rest of the year. The next water will enter the storage only during the next monsoon.

Since storage (for example underground tanks) is costing around Rs.10,000 per cubic metre, we would require for a storage from which we can draw 1000 cubic metre per day (about 300,000 cubic metre totally) an investment of 10,000 x 300,000 Rs = 300 crore. A desalination plant which produces the 1,000 cubic metres every day fresh would cost only 7 crores.

The further costs or problems would be that harvested rainwater is by no means drinking-water, nor can be used as domestic water. It would have to be processed further, while desalinated water is the purest drinking-water you can imagine.
Further, to produce such a huge storage capacity (on average we would require a storage capacity of 200 cubic metres per Aurovilian) is neither possible nor would it be very nice in terms of our environment. The carbon-footprint, for example, to create a concrete underground storage facility of 200 cubic metres volume would be tremendous.
The most important point, however, is that with every cubic metre of water harvested from the rain and stored for later consumption, we would be depriving the ground-water by that same amount, as it would otherwise have percolated into the aquifer. In contrast, every cubic metre of fresh water produced from desalinated water will finally land up either in the aquifer or will evaporate and come down as rainfall at a later point in time.

So from all aspects, financially, environmentally and practically, rainwater harvesting is not a viable alternative which could compete with desalinated water.

In the end, the reality is that all the talks and schemes for rainwater harvesting are little more than a well-intentioned oral exercise, as nobody has the money, capacity, space and required infrastructure to set up such a monstrous water-storage system that would be required for Auroville. Imagine, for a population of 50,000 people, we would require storage-space costing 7,500 crores.

 

The desalination plant is already well on its way. The land is purchased (from Auroville), and we are at present in the phase of getting all the necessary permissions from the various Government departments. We expect that this process will be over in 1½ to 2 years from now. During this time we intend to fix already the pipes from the beach up to the Matrimandir area. The plant itself will be an imported turn-key plant from Germany, coming in two containers. So we hope that within 2 to 3 years from now we will be able to produce 1,000 cubic metres of fresh-water every day for Auroville’s drinking/domestic consumption.