"Does anyone have any thoughts?"
Here goes: this is not a new company, even if the ideas they are commercializing are novel. In it's history, CTGI has never lacked for credible potential: the landfill gas deal with Dupont, LTC and now CO2 scrubbing.
At some point, and I believe it will be this year, CTGI needs to prove that at least one of these ideas can make $$. They don't actually have to make the $$ this year, but they need to demonstrate $$ making-potential beyond the "big idea" step.
FDA, CE mark, a partner who brings $$ to the CO2 party- any of these confirmations would signal to investors that CTGI has actually gone beyond ideas and can be valued as a revenue generating enterprise. Until this happens, we're looking at low volume trading days in a narrow range, with the occasional pop attributable to some pump-newsletter.
Landfill gas was supposed to pave the way for LTC. Ironically, it could easily be the other way around.