Trust me if it worked theyd be busy dropping off dump trucks of money at the bank instead of putting out news reports and being secretive. Has anyone ever heard of a bacterium that photosynthesizes so where is the energy coming from since making hydrocarbons from co2 and water is an massive endothermic process?
You're right that it's an endothermic process, so energy has to be added for that to occur. There's more energy in hydrocarbon bonds than in CO2 and H2O. I'd presume solar or geothermal energy, and a relatively low efficiency factor, along with byproducts.
World oil consumption is currently ~90Mbbl/day, so it'd take a huge acreage to replace that.
Properly design of genetically engineered bacteria should ensure that they can't survive outside of an artificial environment, but that doesn't mean they can't transfer genetic material to other bacteria which would obviously exist in such enormous cultures, bacteria that can survive in the wild...