1.1 Why Biofuels?
Part of the purpose of the course is to help you to understand why biofuels are needed and how to make them, at the current state-of-the-art.
Why biofuels? To look at the situation a little more broadly, the question then becomes: why alternative fuels?
As climate change becomes an issue of ever-stronger concern in the world, stronger efforts are being devoted to tackling this issue. The International Energy Agency (IEA) has recently proposed the 2 °C scenario (2DS) as a way to handle the climate change issue. The 2DS has become a largely used quote for many policymakers and scientists. The 2DS scenario requires that carbon dioxide (CO2) emissions in 2060 should be reduced by 70% in comparison to the 2014 level. The transport sector plays an important role to achieve this goal considering that the transportation sector is responsible for about 23% of total CO2 emissions. Although electricity has been considered as a promising option for reducing CO2 emissions in transportation (Yabe, Shinoda, Seki, Tanaka, & Akisawa, 2012), transport biofuel is estimated to be the key alternative energy in the transport sector (Ahlgren, Börjesson Hagberg, & Grahn, 2017). The share of biofuels in total transportation-fuel consumption by 2060 is predicted to be 31%, followed by electricity at 27% based on the mobility model results of IEA for the 2DS. Biofuels production must be increased by a factor of 10 to achieve this goal (Oh, Hwang, Kim, Kim, & Lee, 2018). In addition to the need for climate change adaptation, the increasing concerns over energy security is another main driver for the policy-makers belonging to the Organisation for Economic Co-operation and Development (OECD) to promote the production of renewable energy (Ho, Ngo, & Guo, 2014). Last but not least, world energy demand will continue increasing. The world energy demand was 5.5 x 1020 J in 2010. The studies predict an increase of a factor of 1.6 to reach a value of 8.6 x 1020J in 2040. The bioenergy delivery potential of the world's total land area excluding cropland, infrastructure, wilderness, and denser forests is estimated at 190 x 1018 J yr-1, 35% of the current global energy demand (Guo, Song, & Buhain, 2015).
In short, there are three main reasons to develop biofuels (Fig 1.1):
- to meet the needs of increasing energy demand;
- dependence on foreign fuel sources can be problematic, depending on US domestic fuel production;
- to reduce greenhouse gas (GHG) emissions.
We will explore each of these reasons in more depth in the following sections.
Ahlgren, E. O., Börjesson Hagberg, M., & Grahn, M. (2017). Transport biofuels in global energy–economy modeling–a review of comprehensive energy systems assessment approaches. Gcb Bioenergy, 9(7), 1168-1180.
Guo, M. X., Song, W. P., & Buhain, J. (2015). Bioenergy and biofuels: History, status, and perspective. Renewable & Sustainable Energy Reviews, 42, 712-725. doi:10.1016/j.rser.2014.10.013
Ho, D. P., Ngo, H. H., & Guo, W. (2014). A mini review on renewable sources for biofuel. Bioresource Technology, 169, 742-749. doi:10.1016/j.biortech.2014.07.022
Oh, Y. K., Hwang, K. R., Kim, C., Kim, J. R., & Lee, J. S. (2018). Recent developments and key barriers to advanced biofuels: A short review. Bioresource Technology, 257, 320-333. doi:10.1016/j.biortech.2018.02.089
Yabe, K., Shinoda, Y., Seki, T., Tanaka, H., & Akisawa, A. (2012). Market penetration speed and effects on CO2 reduction of electric vehicles and plug-in hybrid electric vehicles in Japan. Energy Policy, 45, 529-540.