"I would prefer to have invented a machine that people could use and that would help farmers with their work - for example a lawnmower."
Sitting in the pondering place, I pondered this: Where does vegetable oil come from?
The answer, of course, is that plants make it.
We have an oil-based economy, and we're running out of oil. But that's just the "mineral" petroleum, the stuff that's prehistoric. What about the stuff that the plants make?
Sure, plants can't make enough. It would be just like some nay-sayer somewhere to point out the number of acres we'd have to plant in Canola in order to make enough oil to fuel a single fleet of city buses. They'd probably say it's not cost effective, and they'd probably be right. But what about bio-engineering? How does the Canola plant make it? Or the Hemp plant, or the Olive tree, or any other plant? And what's to stop us from bio-engineering an organism to do just that?
Plenty of things, I'm sure, but most of them are moral or entail engaging foresight, and western capitalism doesn't have much history of respecting moral reasons. Or of thinking beyond the end of the depreciation cycle.
In any case, it's true that plants are very good at processing natural materials into more complex and very different natural materials. For example, they can make oil from organic waste. Or from cellulose. But plants are clearly not efficient enough. To even begin to feed the demand for fuel and synthetic plastics, we would need to operate at fairly high levels of efficiency. Fields of canola, regardless of how verdant, would not cut it.
But foetid swamps full of bacteria just might. To get the volumes we need, we would need to use open spaces, like swamps. We could digest whole forests, whole biomes, of cellulose, turn them into swamps, to get the hydrocarbons we want.
Gaseous hydrocarbons or light alcohols would probably be better for generation purposes, to drive our fuel cells, but we'd still need long-chain petrochemicals to make plastic. So I could envision different "crops," including even some semi-refined plastics.
Some of those crops would be quite hostile to life. The biological processes would most likely generate some rather toxic byproducts. And at the point where this type of production becomes necessary, I have to wonder whether the people who did it would care. These would, after all, be people arrogant enough to farm oil in an open swamp. If the global climate is sufficiently broken, all care might be thrown to the hot, dry winds. Or the fuming, damp winds, as the case may be, as we loose our hydrocarbon-synthesizing organisms onto the world and let them digest its organic waste matter into fuels.
I could envision great, sealed cities on the edge of seething hydrocarbon swamps habitable only by the most adaptable of organisms, and tended by fleets of fragmentarily sentient fuel-cell powered robots. Eventually, the robots might form their own cities (or be organized into them by a retreating humanity), existing only to tend (and perhaps contain) their swamps.
These robot cultures would evolve; they would not remain static. Evolution would apply to them as it does to us. This is where the admonitions of the Singularitarians would apply, because eventually our machines, once we are no longer an active influence upon them, will have to find their own reasons for living.