I know it is an old post Charlie but I was serious about decommissioning as being green jobs.... removing hydrocarbon infrastructure and making good the sites and responsibly dealing with pollution issues is as important as building the cleaner replacements but you have to be prepared to travel and the big money is offshore which requires offshore tickets although there may be funding assistance for that. I assume with your prior job you have a had training with dealing with potentially hazardous materials? That 2 years in the recycling industry can be spun up into a CV if you add all the onsite training, happy to help by pm if you think that would be useful.
Are you still considering this as a career route?
What do you want to do? Are you good with your hands? Does working outdoors appeal? It is such a wide area to consider. Have you considered going self employed? If you are in a big city you may be able to create an environmentally sensitive House Clearance business... people don't really want all their loved ones unwanted possessions ending up in landfill without any effort to sort but it is hard to see an environmentally appealing solution during grief... a recycling and up-cycling service may be very appealing and the spoils of house clearances can be very good, my cousins used to do it and the valuable stuff they used to get was shocking.
If it is the heavy infrastructure that appeals then local papers and the planning office will give you details of projects in the pipeline from wind farms, solar farms, anaerobic digesters, etc, even change of use for a building... you have the chance of getting in on the ground and it shows initiative, many years ago I did the same to pick up security work and got most of the contracts I found like that
I think the solar industry is pretty competitive though going on the comments of a few members on here... some of the solar equipment suppliers run short training courses I believe if you do fancy that route but you will need to know some basic electrics / electronics I'd have thought, not sure if you need a sparkies cert in this country