Biomass is already competitive for heat, for example. In regions, we are underusing biomass for heat production, for example. In big centres, it's harder, but in regions close to where the biomass is produced, this is already competitive.
Then, if we're talking about biofuels and biogas, the competitiveness comes in, essentially, through regulation, so you have to impose it, because the costs are too high. The reasons for this are environmental, and that's how we justify it.
Even without the price on carbon, regulation on fuels—for example, clean fuels—plays this role to increase the value of these products.