When does a carbon tax on fossil fuels stimulate biofuels?

A carbon tax is an efficient economic instrument to reduce emissions of carbon dioxide released from fossil fuel burning. If designed properly, it could also help significantly to promote renewable energy. Using a multi-sector, multi-country computable general equilibrium model this study investigates under what circumstances a carbon tax would help stimulate penetration of biofuels into the energy supply mix for road transportation in various countries and regions around the world. This study shows that a carbon tax cum biofuel subsidy policy, where a carbon tax is introduced to fossil fuels and part of the tax revenue is used to finance the biofuel subsidy, would significantly help stimulate market penetration of biofuels. On the other hand, a carbon tax alone policy, where the entire tax revenue is recycled to households through a lump-sum transfer, does not help stimulate biofuels significantly even at higher tax rates. Although the carbon tax cum subsidy policy would cause higher loss in economic output at the global level as compared to the carbon tax alone policy, the incremental loss is relatively small. The key policy insight drawn from the study is that if a carbon tax were to be implemented in an economy for the purpose of climate change mitigation, recycling part of its revenue to finance biofuel subsidies would significantly help stimulate biofuels.