Understanding the historic controversies and present-day challenges surrounding biofuels

For all the environmental benefits of electric vehicles (EVs) and hydrogen fuel-cell vehicles (FCVs), it would likely take decades to displace the prevailing internal combustion engine vehicles (ICEVs). When even a moderate mitigation scenario forecasts EVs to comprise less than one-third of all passenger vehicles by 2050, one wonders if anything can be done to reduce road transport emissions during this interim period. Biofuels are an existing option which can help bridge this transition gap, with its major categories and developments summarized in the video below.

Much of the controversy surrounding biofuels appear to be targeted at its first-generation categories, which competed against food crops for the use of agricultural land, sparking discontent in the Global South due to reduced affordability of food. From an ecological standpoint, destruction of natural habitats for first-generation biofuel production resulted in local biodiversity loss exceeding that from petrol and diesel in >90% of sites examined, being aggravated where these plantations displaced existing biodiversity hotspots. Other negative implications including water scarcity, greenhouse gas (GHG) emissions and aquatic and atmospheric pollution brings into question if biofuels truly yield their purported environmental benefits.

Source: Verdade et al. 2015, adapted from FAO, 2007

Perhaps in response to these criticisms, second-generation biofuels have gradually emerged, utilizing lignin, cellulose and hemicellulose organic polymers from primarily non-edible plants as feedstocks. These feature several improvements over their first-generation counterparts, ranging from reduced fertilizer inputs for perennial grass cultivation (resulting in lower GHG emissions, toxicity and eutrophication) to increased avian diversity in taller Swedish willow plantations. Although the downsides of biofuels are far from being eliminated, any progress is certainly welcome!

Nonetheless, net environmental impacts of biofuels remain heavily dependent on the origin of underlying cultivation sites, hence, cannot be easily generalized even within the same crop species. Using second-generation Jatropha biodiesel in Brazil as an example, life-cycle assessments of GHG emissions varied from a 60% increase over conventional diesel where cerrado woodlands were displaced, to an 85% decrease when grown on degraded farmland, attesting for the outsized influence of land-use change. While these case-studies emphasize the importance of choosing biofuel farming locations without infringing on natural habitats, doing so would be impractical if mass-production of biofuels become a reality. Consequently, contemporary biofuels fall short in addressing modern demands of sustainable road transport, necessitating the search for other solutions.