The Oil Drum: Europe

Thank you Andy, I wasn't aware of that nozzle change needed to use Town Gas. Still which is the cheapest: to change the nozzles or the additional FT process to get to methane?

Empirically it seems to me that changing the nozzles might be less expensive, and it's done just once. Going for methane an EROEI loss would have to be permanently accepted. The problem is that you can't change the nozzles at every place at the same time.

I would also expect to see the complete decline of Natural Gas electricity generation.  Plus many households may transition onto storage type heating using surplus Nuclear electricity generated during the night.

This is a very important observation, though I don't know any system that allows you to do that. Electric companies would have a much easier task if it weren't for the variations on demand from daytime to nighttime. If those curves on the last graph were straight lines instead, a lot of waste would be spared on the switch on/off processes.

To be exact, if this were to be done, the gasifiers would be located near a water source.  They would produce mainly a CO-H2 mixture (syngas or town gas).  This would be converted to pure H2 via water-shift units for use in power generation.  For plastics and fertilizer the syngas could be used as is.  For home heating it would be methanated for compatibility and safety.

The principle reason the nozzles had to be changed was the difference in flame velocity not calorific value. Natural gas has a flame velocity of about 35cm/s. Town Gas with a 50% hydrogen content had a flame velocity of about 100cm/s

Gas is burnt in domestic devices but squirting it through a first nozzle to produce a fast flow, sucking air through an adjacent aperture to mix with the gas by a venturi effect and the passing the mixture through a second nozzle and burning it as it emerges.

In this way you get complete combustion rather than just the hydrogen burning leaving some of the carbon as soot.

 The gas air mixture has to emerge from the second nozzle at somewhat higher than the flame propagation velocity in that gas. As the gas spreads out from the nozzle it speed drops to be below the  flame velocity. The flame point will stably sit at the distance away from the nozzle that the gas velocity equals the flame velocity.

If the gas emerges too slowly through the nozzle the flame will blow back through it to the first nozzle. If it is too fast the flame front will be too far away from the nozzle and be prone to being blown out by draughts.  

I remember our house being changed over. It was done area by area and our house was without gas for about 6 hours while the change was made.

I think a much better idea would be the West European countries to build the large scale coal-fired central heating we already have in the east, at least in the bigger cities. No need for expensive home burning appliances, no fear of explosion, poisoning etc. And potentially the CO2 can be sequestered.

With good pipe insulation the efficiency of such systems can be more than 50% - higher than the efficiency of gasification + F-T conversion. In addition such systems can utilise the waste heat from thermal plants, the fuel maybe waste biomass etc.

With population continuing to concentrate in big cities, I see at least 50% of the households covered by central heating. The main obstacle is that someone will have to commit to spending the huge resources for it, but better do it now, while we are still not pressed to implement partial and ineffective solutions.