|To me, the future of renewable gas is clear – the methanation of a combination of carbon-rich and hydrogen-rich gas feedstocks.
Sticklers for detail will be asking “Why go to the bother of upgrading biomass-derived synthesis gas via methanation ? Why waste the energy ? Why not simply burn the BioSNG as it is ?”
My answer is, well, it’s like fast-forwarding hundreds of millions of years.
|Instead of the fossil fuel process – where great extinctions of Life on Earth led to the deposition of biomass that got subducted under moving plates of the Earth’s crust and then cooked into useful hydrocarbons – making renewable gas does this in an instant.
It’s the addition of the extra hydrogen – split by electrolysis from water, then combined to the carbon-rich gas by methanation – that raises the energy content of the biologically-sourced gases.
The resulting methane-rich BioSynGas is a much more valuable fuel for electricity generation and, when cleaned of impurities, for use in vehicles and the gas grid network. It is easily stored, and readily available on demand.
It can be used to burn in power stations, to provide backup, as and when required, for variable and intermittent sources of renewable electricity generation, such as wind power.
And what’s even more interesting is what I call the “backend recycling distillation” potential. Biologically-derived gases often have difficult contaminants. However, if carbon-rich gases are collected from the flue gases from burning BioSynGas in power stations, the resulting gas feedstock will be less contaminated than the BioSynGas that went in.
Carbon-rich gases that are outputs from burning BioSynGas in power plants can then be methanated once more, using hydrogen derived from water to raise the energy content, and this product will be much easier to clean for use in vehicles and gas grids.
So, the carbon gases from biomass, combined with renewable hydrogen from water, get used once to generate electricity, and then get recycled (with the addition of more hydrogen as input) into almost tap-ready fuel for engines and domestic boilers.
That’s what I call brilliant !
[ UPDATE : Note well that the “S” in “SNG” is debated – “Synthesis”, “Substitute” or “Sustainable” appear to be near the top of the list of choices. Or we could just call it “snoog” – it sounds nice and cosy…snug, in fact. ]