Chris Newman offered the following response:
What you say about the effects of oil price rises is quite correct. And yes, consideration is being given to the use of coal as an alternative steam locomotive fuel. No serious thought has yet been given to burning coal in the 5AT, we have for some time been looking at the possibility of developing a freight haulage version of the 5AT specifically for coal haulage duties that would burn coal as its fuel.
I have done quite a lot of work over the last four years in developing and putting forward economic arguments in favour of steam traction wherever coal and labour costs are low. In fact I presented a paper on the subject at the conference on modern steam traction at York in December 2006, and have developed my cost models quite a lot further since then.
As for the 5AT, it is still difficult to consider coal as a fuel when the rest of the railway is using gas oil. Whilst ever that situation exists then logistically gas oil will remain the preferred choice, bearing in mind that the 5AT is intended to operate in the modern railway environment. Of course it will not be able to compete with diesel traction in terms of fuel consumption, which is why it is intended to operate only in the tour train market in which steam traction has particular appeal. Furthermore, the use of oil as fuel brings with it several subsidiary advantages including ease of firing, reliable combustion and steam generation, zero spark emissions, no tube abrasion, no ash disposal, no smokebox cleaning, and greater operating range.
Lump coal is a nasty fuel that is difficult to fire, unreliable in its combustion, creates ash, emits char that erodes tubes, fills up smokeboxes and throws out sparks. GPCS combustion certainly reduces these problems but it does not eliminate them whereas the use of pulverized coal would, which is presumably why power stations all prefer to use pulverized coal these days. The technology was successfully developed and tested in steam locomotives in Germany and Australia and the UK the 1940s and 50s, so presumably it can be resurrected for use again. Certainly it would be the best option for the 5AT if/when oil prices become so high that the railways have to think about alternatives to diesel traction. In the meantime, if we can develop a market for steam traction for coal haulage in developing countries, then this would be where pulverized coal combustion technology should be tried and perfected. (See note below for further comments on pulverized coal.)
A worrying but little-known fact is that even coal is not an inexhaustible fuel. Whilst "peak oil" is just probably around the corner (if it's not already past), "peak coal" is not so many years away.. Indeed Brian McCammon reports that peak coal may be only 17 years away, and if he's right then coal is not going to be a panacea for an oil-depleted world. Our children are going to be facing some difficult times in the future, and more than likely we will witness them ourselves. Nuclear power will inevitably have to take up some of the demand for power, but I'm not optimistic that renewable fuel and power sources will be able to fill the gap. Food-based bio-fuels may keep rich countries' SUVs going, but they are not going to help the poor and the starving. The best option that I can see is "fuel from waste" but the UK and other governments seem to be astonishingly slow in promoting it.
There are copies of several papers on the Links and References page of the 5AT website, including Chris Newman's 2008 CORE 2008 paper "Feasibility of Steam Traction of Coal Haulage in Developing Countries" and his 2006 York paper "Traction Cost Comparisons for Indonesian Coal Haulage"; Brian McCammon's 2007 paper "Review of Carbon Neutral Fuels with Potential for Use in Modern Steam Locomotives". In addition, a reference to "Coal - Resources and Future Production" was published by the Energy Watch Group in March 2007"
Note: Pulverized coal combustion could offer significant advantages over lump coal combustion. For instance, it would eliminate the "grate limit" phenomenum and problems associated with clinker formation, spark emissions and ash disposal. Stoking could also be automated much more easily making one-man operation a real possibility. Effectively it would have all the advantages that oil-firing confers. The technology was in fact used successfully in Australia, Germany and the UK in the 1920s, 30s and 50s, as described in Chapter VI of a book titled "Brown Coal" by H. Herman (one-time State. Director of Geological Survey) published by the State Electricity Commission of Victoria, Australia in 1952. The chapter titled "Brown Coal Dust Firing for Locomotives" is reproduced here.