The proposal for high-rise agriculture as an alternative to land-based farming is interesting (Vertical growth is where S'pore's future lies, by Mr Paul Chan Poh Hoi; May 19).

If it works, we can get fresh produce right in our own backyard, drastically cut transportation costs, free up precious land for development, lighten the natural pest load and be less pollutive from fertilisers and herbicides.

However, to date, skyscraper farms are a scientific theoretical fantasy and their large-scale feasibility is questionable.

Among other things, the huge amounts of artificial light, sophisticated and expensive electrical, irrigation and waste collection paraphernalia plus carbon dioxide-generating systems needed for intensive high-rise farming are formidable obstacles.

Failed projects will end up being money drainers and blights on the landscape.

At present, more energy needs to be put in than can be derived from the finished product.

It would be wasteful to pioneer skyscraper farms when fresh produce is still easily and cheaply available from countries with the natural resources to produce it well and at low costs.

Yik Keng Yeong (Dr)