From Martin Evans
Have the advocates of reefs made of concrete balls carried out a full
cost-benefit analysis of their scheme?
(This Week, 20 June, p 10). I accept that
the energy costs of producing and shipping the balls would in time be paid back
in carbon fixed. But given the importance of limestone as an aquifer, home to
wildlife and archaeological treasures and provider of landscape and recreational
amenity, it is more valuable in situ than quarried for making concrete
(see “Bleak prospects for limestone”, 13 May 1989, p 56).
I suspect that it would prove more cost-effective to protect or restore
existing natural reefs: in some parts of the world these are threatened by,
among other things, sediment from quarries.
Surbiton, Surrey
