EGEE 439
Alternative Fuels from Biomass Sources

1.1 Why Biofuels?

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 by 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 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. Biofuel 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).

Circle with 3 sections energy demand, climate change, energy security and an arrow from each one to the next.
Energy Demand, Climate Change, Energy Security: Three main reasons to promote sustainable biofuel production and usage.
Credit: Dr. Hilal Ezgi Toraman © Penn State, is licensed under CC BY-NC-SA 4.0.

In short, there are three main reasons to develop biofuels:

  1. to meet the needs of increasing energy demand;
  2. to reduce greenhouse gas (GHG) emissions; and
  3. to improve energy security by reducing dependence on foreign fuel sources because it can be problematic, depending on US domestic fuel production.

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.