Climate change is caused by high CO2 levels in the atmosphere. That’s what's wrong
Knowing what's wrong the easy part, doing something about it is hard. Internal combustion engines that run on bio-fuels do produce CO2 in the exhaust, anyone that tries to tell you they don’t isn’t telling the truth, but growing whatever you use to make the bio-fuels absorbs so much CO2 that you end up reducing the total amount of CO2 in the atmosphere.
Also bio-fuel engines produce less emissions, and the CO2 they release is ultra low footprint. Atmospheric CO2 is taken in by the growing plant which is made into bio-fuel. So effectively all bio-fuel engines run on carbon negative fuel. All bio-fuels are only a few years old so they are ultra low carbon footprint. As bio-fuels are made from plants and plants take the carbon in them from the atmosphere they are effectively carbon negative
Internal Combustion engines where originally designed to run on bio-fuels. Optimized bio-fuel engines even out-put much better amounts of energy, bio-fuels just have to be used in an engines optimised for them. Diesel engines need no changes at all, but running ethanol is more complicated the compression needs increasing to perhaps to 13, 14 or 15 to 1 from between 8, 9 or 10 to 1 to 1. Which is the optimal compression for petrol, my own engine is 16.51 to 1, but is strongly built as originally the block was designed to be both petrol and diesel with different pistons, con-rods and ignition system
A high compression engine is much more thermodynamically efficient and so there is much greater benefits although it would mean assembling the engine with different parts, but a diesel’s short engine could be identical to an ethanol engine’s the only difference would type of ignition. Dedicated ethanol engines of diesel-like compression are just as powerful or even more powerful than petrol/gasoline engines and would be just as cheap to build. The government in the UK wants to ban new petrol and diesel cars in 2030, because to reduce climate change we need to reduce CO2 in the atmosphere, I applaud that, I just think prioritizing electric cars is not the best thing. The UK is also guaranteeing that all the UK’s electricity the best way to that. The government is also from zero carbon sources. To make that work lots of charge points have to be built and the car buying public has to have confidence that they can get a charge easily and the car does as good mileage between charges.
A much cheaper way would be to stop building cars that run on petrol and diesel and build cars that run on ethanol and bio-diesel cars with engines of 13, 14 or 15 to 1 compression instead. Investment to change petrol and diesel cars to ethanol and bio-diesel cars would be nothing much less than to go electric. You would have to make the ethanol or bio-diesel. Ethanol can be made of many things recycled things mainly, card, paper, garden waste, Cellulose even cane sugar or corn syrup. Bio-diesel is made of recycled cooking oil any type of vegetable oil really.