Close the Sustainability Loop


by Satish V. Kailas

Sustainability is the key to the future of this planet. If daily living is not made sustainable then the lifestyle that we are used to would not be sustainable. Are we leading a life that is sustainable? The answer to this, I think, is quite clear; no we are not. The question that needs to be asked is how to make our lifestyle sustainable. This is easy to explain with “closing the loop” approach.

We take resources from this planet, process them, manufacture them, use them and then discard them. From time immemorial we have been used to throwing this trash without a concern of what happens to the trash. In many societies the trash is collected well and then dumped into the ocean. The hope being that “out of sight is out of mind” is an unacceptable approach. This is leading to a disaster of an unimaginable scale. Clearly, what happens to the trash is of utmost importance.

Further, the resources that are being extracted cannot be sustained as the planet is not able to replace the material that is being extracted. When we look at the products being manufactured and used today most of the materials used in making these products are non-replenishable. Clearly, this cannot be sustained as these resources will run out. It is like a battery being charged for use. If the rate of withdrawal of power is faster than the rate of recharging, the battery will drain out sooner or later. This loop is what can be called an ‘open loop’.

The consumption of crude oil at the rate that is prevalent today is, for example, what falls in this category where the crude, which was produced by Nature, is being used at a rate faster than it is being produced and so mankind will run out of this energy source. An open loop is one where the rate of use of the materials extracted is either not replenished (steel, copper, potash as fertilizer, nuclear energy are examples) or the rate of usage is faster than the rate of replenishment (crude, natural gas, coal are examples). How to we make this sustainable? The only way is to ‘close the loop’.

In a loop, where the material being used is not replenished, the material has to be recycled. And this recycling has to be 100%. A little lower than 100% and the cycle will last for a longer time but will finally collapse. The open loop, where the rate of consumption is faster than the rate of replenishment, the only way out is to reduce the rate of consumption till it matches with the rate of replenishment; or increase the rate of replenishment till it matches with the rate of consumption. This also includes the kind of energy used to manufacture these products. Clearly, we have moved away from this since the dawn of the industrial revolution and today are moving faster and faster away from this sustainable cycle. A very close relook into the direction development is taking us is a crying need of the hour.

An example of how, in the name of development, we have made a sustainable activity unsustainable is farming. This is an example where a closed loop was opened up in the name of development. Farming was an activity that was carried out for centuries by mankind without a problem. This was a closed loop as all the products used in farming came from resources that were replenished. This included the fertilizers and water. The fertilizers came from farm animals and other waste from the farm and from the silt that was collected from the lakes and ponds that many regions, especially rain fed regions, had.

The introduction of chemical fertilizers during the start of the “green revolution” opened this loop, as the chemical fertilizers were made from hydrocarbons (urea) or mined (potash). In the process the farmers stopped desilting the lakes, thereby reducing their storage capacity, and over a period of time these water bodies have almost zero storage capacity. This led to the lower recharge of ground water and with the increase in the number of irrigation pumps the water table in many regions have gone down to precariously low levels, if ever water is available. Thus, a “closed sustainable loop” based farming method adopted by mankind for centuries, was opened up and will, over a period of time, collapse.

To make this sustainable we need to move back to the “closed loop” practised for centuries by mankind. The key message is – “Science without Sustainability and Sustainability without Science are both meaningless”, “close the loop” and one might add “power and efficiency are secondary”. The last point needs clarification; there is no point in having a system that is powerful and efficient, if it is not sustainable. And a cycle is either sustainable or not-sustainable. The concept of a more sustainable cycle is something that is not correct and even if a single material or process in a product is not in a “closed loop” the whole product is not sustainable.

Satish V. Kailas is with Department of Mechanical Engineering
Indian Institute of Science, Bangalore


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