Emotions enfeeble costmongers

5 February 2002

Risk analysts are forever debating the monetary value of a human life. They want to quantify, financially, such hazards as fatal accidents. Valid numbers are hard enough to obtain for the cost of foreseeable deaths. They become even more elusive when assessors try to put price tags not on lives but on livelihoods and lifestyles: as they should when they consider the possible destruction of habitats by hydroelectric schemes, or when they think about the mathematical probability of radioactive releases from nuclear plants.

The costing of biodiversity loss seems to me to be another problem that is even more intractable than the costing of accidental death. A particular case makes the point clear. Take the 180MW Kihansi hydro power station in Tanzania. I first read about this a year ago in our sister journal, International Water Power & Dam Construction.

Controversy flared then over how much of the available water flow the Tanzanian Electricity Supply Co should use for power generation. Full utilisation would apparently imperil the survival of an amphibian animal, the Kihansi spray toad. This creature, to be found only in the Kihansi gorge, was declared to be unique among toads in giving birth to its young. To prevent its extinction, said its intending protectors, either the output of the station had to be curtailed or the toad population had to be moved elsewhere.

Personally, I cannot believe that costings of the alternatives here could soundly help to justify a decision on what to do. Anyway, of what consequence would economic comparisons be to those who would rate the saving of any non-human species above the saving of human life, or to such others as would not endure a moment's brown-out to spare the world's entire stock of a rare species? And would those comparisons carry much more weight for people between those extremes? Whether to preserve this unique beast required judgement based on scarcely quantifiable values: and the same is required on many another, if not every, environmental issue. Pebblecounters' methods are unlikely to help much, if at all.

Thrill with superheat by-products

Some of you may have first learnt about superheated steam so long ago that you will be surprised to hear the stuff described as 'a type of matter that until a few years ago was regarded as a chemical curiosity'. Well, that is the way it, among other 'supercritical' fluids, looks to certain researchers in UK and Russian universities, as reported in the UK science journal, EPSRC Newsline.* Not that such fluids have failed to make their mark before now. Coffee is decaffeinated with supercritical CO2. The same agent also pulls the essential flavour out of hops. And so on. But those chemists in Nottingham and Moscow are finding new applications for supercritical fluids; beyond industry, too, for such loftier purposes as growing human tissue and body parts in the laboratory.

Plain H2O loses its plainness as it approaches critical conditions. As well as having the interesting thermodynamic properties familiar to superheated steam users, H2O at nearly its critical temperature (374ºC) starts behaving like acetone. Organic compounds that are insoluble in room-temperature water will cheerfully dissolve in supercritical H2O. Aqueous saline solutions, on the other hand, become impossible if the aqua is supercritical. The advancing Anglo-Russian team has shown that oxidation catalysts prepared in supercritical H2O can be more active than their conventionally produced equivalents. This may be good news for manufacturers of automobile exhaust-cleaning catalysts, for example.

Even as I write, some computer-aided designer is undoubtedly scheming a by-product line for his new power station project. His employers' image-builders are surely being just as creative. Can you not picture them extolling what they might imaginatively dub the C5P3 Concept, perceiving this to be a snappier, more high-tech-sounding tag than their fully spelt-out Car-Cleanup Combined-Cycle Power-Plus-Processing Complex? And can you not picture them further, planning the project, to be launched if motorists desert the internal combustion engines and take to fuel cells instead? Marketing magnificoes have to be ready for anything and everything these days.

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