We have ways to synthesize hydrocarbons - it's just that they require very cheap energy to be practical. Also some things (like asphalt) are only cheap because

We have ways to synthesize hydrocarbons - it's just that they require very cheap energy to be practical. Also some things (like asphalt) are only cheap because we're already refining oil to make fuels. It's essentially a byproduct. It may be that other road surfaces become more economic if the alternative is to refine oil just to get the asphalt.