It's an interesting calculation, but there would be plenty of projects that give a better return in carbon terms than the Heart of Wales Line - electrifying just about any other non-electrified line for a start.
Yes, but the result is still a net positive.
It just demonstrates that the carbon intensity of fixed infrastructure like this is suprisingly low, which is why I have such short shrift for people who complain about the amount of concrete and steel needed for zero carbon infrastructure.
And even more outside the railway. It's also likely that not long into the 80-year period something like a hydrogen train would become the best way of reducing CO2 on such a fringe rural route, since it would eliminate the emissions without any infrastructure work other than perhaps a filling station somewhere.
And the electrolysis infrastructure, and the hydrogen storage infrastructure, and the electricity distribution infrastructure that supports the electrolysers, and the extra power generation capability to account for the low end to end efficiency of the hydrogen production process, and replacing some of that since there is no way the bulk of it will last 80 years (the electrolysis cells for certain).
There is a massive structural aversion to capital expenditure in the UK, which can be demonstrated by the Treasury demanding unrealistic rates of return for capital investment which are drastically in excess of what the real rates in the market are for government debt.
Capital Expenditure is an anathema because the people in charge are dreaming of a return to the interest rates of the 70s and 80s, which will never come again.
Hence they put their hopes in magical hydrogen trains that might be available in 20 years to save them.
EDIT:
ANd all this is before we consider the possibility of adopting guyed wooden electrification masts, which would have negligible carbon impacts as the concrete mast bases and steel are eliminated.
EDIT #2:
The current traffic density is 4 and 2/3rds trains in each direction on Monday-Friday, 4 trains on Saturday and 2 on Sunday.
THis means ~29 trains in each direction per week. Or roughly 60 carriages per week over the track.
That means something like 3000 carriages per annum, rather than the 900 assumed in the estimate.
Which suggests that carbon payback time is only
24 years. Assuming no steps are taken to reduce the carbon footprint of electrification
And that assumes single car trains, apparently from 2022 it will be two-car 170s.
Which implies a time of something like
12-15 years depending on their fuel consumption.
Which will be long before hydrogen trains are available.
