Sir – I read the editorial (April 24) about incineration with interest: ‘The best you can say of the county council’s approach is that it has probably given us the cheapest option rather than the best’.

I don’t think it is the cheapest option; not in the long term, and possibly not in the medium to short term either.

One reason is that the county council is ignoring the additional costs of carbon emissions from an incinerator — this is very likely to occur and may add considerable costs, even by conservative estimates. Indeed, I suspect that the council hasn’t included this in its risk register for the proposed residual waste treatment.

Second, the Treasury is now undertaking a consultation about proposed changes in landfill tax which may see the ash from incinerators, in particular the ash which falls through the grate — the incinerator bottom ash, no longer classified as ‘inert’.

Consequently, the cost of disposing of the ash to landfill may increase from £2.50 a tonne to the ‘normal’ rate of £40 a tonne or higher. While the increase in disposal costs may encourage alternative uses of the ash, for example in aggregates, it’s not clear that there won’t be an overall cost increase.

The council has this item — increases in disposal cost for ash — in its risk register but I suspect that it hasn’t properly evaluated its likelihood nor its consequences.

Andrew Wood, Oxford Friends of the Earth