Team:Purdue/Practices

• INTRODUCTION
• BACKGROUND
  • The Problem
  • Organisms
  • Enzymes
• PROJECT
  • Description
  • Project Development
  • Our Solution
• PARTS
  • Team Parts
  • Basic Parts
  • Composite Parts
  • Part Collection
  • Parts Used
  • Parts Submitted
• NOTEBOOK
• ATTRIBUTIONS
• OUR PROCESS
• HUMAN PRACTICES
• SAFETY
• MODELING

Human Practices

Meeting with Industry

To better inform our design and to get a better understanding of current ethanol production practices, our team visited an industrial ethanol plant on July 24, 2015. The Cardinal Ethanol plant located in Union City, Indiana converts corn into ethanol and DDG’s (dried distillers grains) and sells these products mainly to gasoline producers (for blending) and animal feed companies. The facility we visited produces around 100 million gallons of ethanol annually and operates 365 days a year.

After touring the facility, we were able to sit down with the plant manager and Cardinal’s corn stock buyer to discuss the future of ethanol in general and their perceptions of cellulosic ethanol and synthetic biology.

The Purdue Biomakers touring the outside of the Cardinal Ethanol facility

Impact on Project Design

After touring the facility and speaking with the plant manager, our team realized that cellulosic ethanol will have many barriers in addition to lignin degradation before it ever becomes a widespread fuel alternative. Even if the technological challenges of converting the biomass to ethanol were overcome, there would still be many issues relating to input supply and processing. For example, there is already a well­established method to harvest the corn kernel and transport it to the ethanol plant but no similar method exists for harvesting the corn stover, or the leaves and stalks of the crop. If cellulosic ethanol becomes a reality, we would need to find a way to get agricultural waste off the field and into an ethanol plant. Pre­existing equipment would likely need to be customized or designed from scratch to fit the needs of the different feedstock.

Economic Challenges

Even if a new technology was developed to convert the cellulose to ethanol more efficiently, there would still be several challenges before cellulosic ethanol could be considered feasible on a large scale. To make this fuel competitive in the marketplace will require significantly lowering production costs. In 2012, the cost of producing ethanol from cellulosic materials was 40% higher than that of corn.

For our 2015 iGEM project to be feasible, it would need to contribute to lower overall production costs while still maintaining a reasonable timeframe. Enzymatic pretreatment via yeast would need to require less energy, time, and/or money than current chemical and high-pressure pretreatment methods. It would also need to increase ethanol production efficiency.

While cellulosic ethanol has become and will continue to become more cost competitive since 2012, other hurdles related to ethanol in general still remain.

Infrastructure Requirements

One of the biggest obstacles related to widespread ethanol adoption as a fuel of choice is the lack of existing infrastructure. Due to ethanol’s hydrophilic properties and its corrosiveness, it cannot be shipped using pre­existing oil pipelines. If ethanol were to be transported using these pipelines, it would soak up water and impurities, affecting the integrity of the fuel, and it would gradually corrode the pipeline itself.

The inputs for cellulosic ethanol are mainly grown in the Midwest and the Southeast of the U.S., but the majority of the demand for transportation fuels is on the East Coast. If large volumes of cellulosic ethanol are ever produced, there would still need to be a major national infrastructure upgrade to avoid clogging up highways and rail lines.

Current ethanol blending requirements mandate a 10% ethanol to petroleum blend nationwide. However, with the transportation challenges and the greenhouse gas emissions associated with long distance travel, it might make more sense to change those mandates to 85% ethanol for areas local to ethanol production.

Engine Trouble

The other major challenge that must be overcome before E85 (85% ethanol) fuel becomes a reality is flex­fuel vehicle deployment. Current passenger vehicles are only able to handle up to 20% ethanol by volume before performance starts to be affected2. Flex­fuel vehicles, however, are able to handle up to 85% ethanol and can be made relatively cheaply during production. The modifications necessary for flex­fuel capability add only $50­$100 per vehicle, but retrofitting pre­existing vehicles is much more costly2. Higher ethanol levels would also necessitate special pumps at fuel stations to dispense the fuel, but there are currently less 3,000 E85 capable fueling stations in the U.S. and most of them are concentrated in the Midwest.

Sources:

• Biello, D. (20 February 2013). Can Ethanol from Corn be Made Sustainable? Scientific American. Retrieved from http://www.scientificamerican.com/article/can­corn­ethanol­be­made-sustainable/
• Cellulosic Ethanol (2009). Center for Climate and Energy Solutions. Retrieved from http://www.c2es.org/technology/factsheet/CellulosicEthanol
• E85 Fueling Station Availability Is Increasing (7 March 2014). U.S. Energy Information Administration. Retrieved from http://www.eia.gov/todayinenergy/detail.cfm?id=15311

Why Biofuels?

There is an old joke in the energy sector that advanced biofuels are the future, and always will be. Biofuels, defined as renewable fuel created from plants or living organisms, have significant potential benefits, but also present major roadblocks to their widespread adoption as the fuel of choice. The touted benefits of biofuels include the possibility of lower greenhouse gas emissions, less reliance on foreign oil reserves, and a renewable form of energy to power vehicles.

Biofuels can be created from anything from corn kernels and sugar crops to algae and perennial grasses. However, when it comes to producing fuel to power cars, ethanol derived from corn (in the U.S.) and sugarcane (Brazil) has been the only major industrial success, and the term “success” is certainly arguable. Corn-­based ethanol, though initially adopted as an environmentally friendly alternative to petroleum, has run into criticism from environmentalists and many scientists for being bad environmental policy. Ethanol production from corn requires petroleum-­based fertilizers and distilleries are often powered by coal or natural gas. Depending on how it is produced, ethanol can even contribute more greenhouse gas emissions than gasoline1.

Biofuels have also faced controversy over their impact to food production. Corn used to produce ethanol is corn that can no longer be used to feed people. According to the Congressional Budget Office, increased production of corn­based­ethanol contributed to a 15% rise in food prices2. With roughly 9 billion people to feed by the year 2050, some policymakers argue that the world cannot afford to divert agriculturally viable land to biofuels.

Although corn and sugarcane currently provide the best ethanol conversion rates, another feedstock presents the possibility of a more environmentally friendly and sustainable alternative.

Cellulosic Ethanol

Ethanol can also be produced from from cellulosic materials like grasses, agricultural residues, and short rotation woody crops. Cellulose and hemicellulose (collectively called cellulosic materials) provide structure to plants and can be fermented into ethanol, but these compounds must be broken down into sugars first. Converting the plant matter to simple sugars is more difficult than simply processing the corn’s starch or the sugarcane’s sugar. Ignoring the difficulties, though, cellulosic materials have many characteristics which make them appealing as a possible ethanol source.

First, cellulosic materials represent roughly 60­90% of terrestrial biomass by weight. Everything from prairie grasses, to wood waste, to the stalks left over after corn is harvested, contains cellulose. Yet, unlike corn or sugarcane, cellulosic materials are not usually used for food or animal feed. Grasses, like switchgrass, can even be grown as an energy crop on marginal lands not suitable for traditional agriculture.

However, so far, cellulosic materials have only been used on a commercial scale in a handful of plants around the world. One major technological hurdle that must still be overcome is how to access the cellulose molecules so that they can be broken down into sugars and converted to fuel. The cellulose is sandwiched within alternating layers of a compound called lignin which helps give the plant its rigidity and strength. Lignin acts as a barrier to tapping the energy stored within the cellulose. Before ethanol can be made, the biomass must be pretreated to disentangle the hemicellulose and cellulose from the lignin.

Our project explores using synthetic biology to develop a new way to overcome this lignin barrier and to make cellulosic ethanol one step closer to reality.

Sources:

• Granda, Cesar B., L. Zhu, and M.T. Holtzapp. (2007). “Sustainable Liquid Biofuels and Their Environmental Impact.” Environmental Progress 26(3): 233­250.
• Biello, D. Food Vs. Fuel: Native Plants Make Better Ethanol. Scientific American. 16 January 2013. Retrieved from http://www.scientificamerican.com/article/native­plants­on­marginal­lands-to­reduce­food­versus­fuel­from­biofuels/
• Cellulosic Ethanol. Center for Climate and Energy Solutions. 2009. Retrieved from http://www.c2es.org/technology/factsheet/CellulosicEthanol