If we had the energy generation capacity it isn't that hard to replace most chemical feed stocks. The problem has always been that fossil fuel as a reagent is s

If we had the energy generation capacity it isn't that hard to replace most chemical feed stocks. The problem has always been that fossil fuel as a reagent is significantly cheaper than the equivalent energy cost to synthesize replacement reagents from other sources. Fertilizer for example can be produced from atmospheric air, the problem is fertilizer already uses 1% of global electricity production, and not using fossil fuels to do it will increase that energy requirement 10 fold, so 10% of global energy production. Another reason we probably should of invested more heavily in nuclear in the past so we could be in a much better place today.