Final Report: Extraction of Sugars from Algae for Direct Conversion to Butanol

EPA Grant Number: SU834701
Title: Extraction of Sugars from Algae for Direct Conversion to Butanol
Investigators: Hestekin, Jamie , Beitle, Robert , Bevan, Elizabeth , Carter, Ethan , Huslig, Megan , Ivey, Jill , Nakao, Hiroko , Penney, Roy , Rakestraw, Kylan , Rostro, Lizbeth , Stout, Jeremy
Institution: University of Arkansas - Fayetteville
EPA Project Officer: Nolt-Helms, Cynthia
Phase: I
Project Period: August 15, 2010 through August 14, 2011
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2010) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Energy , P3 Challenge Area - Water , P3 Awards , Sustainability

Objective:

The US imports over 60% of its crude oil on an annual basis. In order to obtain energy independence, different biofuels, feedstocks, and technologies must be explored. The production of butanol from algae is being investigated as a sustainable and potentially lucrative liquid fuel source.

Algae are an exciting new feedstock for biofuel production because of their extremely fast growth rate, high oil and sugar content, and ability to thrive on marginal land water. The bulk of the research on algae biofuels to date has focused largely on the use of the naturally occurring oils in algae to produce biodiesel. However, the majority of the energy contained in algae is stored as carbohydrates, not oils.1 Although much research has been done on converting algae oils into biodiesel, little has been done on converting the sugars and starches into usable liquid fuels. This has likely inhibited the sustainable commercialization of algae to biofuel technology.

Past research efforts have made significant progress with electric and ethanol-based solutions toward fueling transportation without the direct combustion of fossil fuels. Butanol is a sustainable fuel that has many advantages over other alternatives, including its low vapor pressure, high energy density, and ability to directly replace gasoline.2 The higher energy density of butanol relative to ethanol allows for better fuel efficiency in vehicles, giving the consumer better gas mileage. In addition, the physical properties of butanol are such that modern gasoline automobile engines can use butanol directly without major engine modifications.

Phase I investigated a method for producing butanol from algae using a novel automated hydrolysis, fermentation, and separation process. The Phase I research team sought to experimentally optimize individual steps and parameters of the process, design and build an automated unit to produce fuel-grade butanol from algae in a batch process, evaluate the sustainability and large scale economics of the process, and design an outreach program encouraging energy and environmental awareness centered around K-12 students. The team used macroalgae samples obtained through the generosity of the City of New York from Jamaica Bay to test the equipment and viability of the process.

Summary/Accomplishments (Outputs/Outcomes):

Experimental Optimization
Experiments were performed to determine optimal operating parameters for each step of the process in order to reduce energy and material waste and maximize biofuel production. Optimal pH, temperature, heating time, and water concentration for acid hydrolysis were found by performing trials to determine the conditions that produced the highest sugar concentrations per unit of algae consumed. Fermentation conditions were determined by analyzing the amount of bacteria required, the ideal pH to encourage butanol-producing metabolic pathways, and the necessary time to convert the maximum amount of sugar to butanol. The optimal distillation conditions were determined by altering distillation heating time, reflux ratio and cooling water temperature.

PEACE-1 Design and Construction
The team designed and completed the construction of a demonstration unit. The Portable and Electronic Algae Converting Equipment unit (PEACE-1) takes approximately 1.2 pounds of dry algae and produces 1-2 oz. of fuel-grade butanol. The unit is 3 ft. x 5 ft. by 9 ft. high, can be transported in the bed of a truck, and is operated and controlled by a touch screen located on the front of the unit. PEACE-1 will be transported to Washington D.C. for the National Sustainable Design Expo in April 2011.

Economics and Sustainability
The PEACE-1 unit was constructed for about $7,000 and requires less than one dollar in operating cost and materials for each batch of operation. Preliminary sustainability calculations were performed for the process to estimate the potential environmental impact of this technology. The combustion of butanol that has been produced from algae is carbon neutral in the sense that the carbon released to the atmosphere during butanol combustion was absorbed from the atmosphere by the feedstock algae. While PEACE-1 uses about $18 of electricity per pound of butanol, for a continuous system based on this design would use closer to $0.60 of electricity per pound of butanol. As PEACE-1 was constructed as a proof-of-concept and experimental prototype, energy conservation was not a major concern in its design and fabrication. However, the knowledge obtained in its construction will be paramount in achieving desirable energy efficiency in subsequent algae-to-butanol production systems. Also, the secondary environmental benefits of algae-to-butanol systems are substantial. The algae not only removes nitrogen and phosphorus from water, reducing human pollution of freshwater and saltwater, but the waste solids from the process can be used as nitrogen and phosphorus fertilizer rather that introducing new pollutants into the environment.

Education and Outreach
The efforts of this project have spread throughout the regional academic community and national level. Groups of students from middle schools and high schools in the region, such as McNair Middle School and Russellville High School, have visited the University and seen demonstrations of the process and a remote control car that runs on butanol. Some of the visiting students even competed in a contest to see who could perform a hydrolysis experiment with the best results. Also, over fifteen middle school science teachers from the region attended a workshop at the University of Arkansas where the algae to butanol process and research was showcased. As a result, many visits to and from various schools are currently being planned.

The Phase I team submitted an entry into the Planet Forward contest in February 2011, a contest intended to allow experts and engaged citizens to weigh-in on energy and sustainability.14 The team received the highest number of internet votes and was invited to be featured on a television special airing in April 2011. Most of the teachers that attended the workshop at the University of Arkansas have stated that they intend to show the Planet Forward PBS Special in their classrooms.

With the team’s success and the project’s relatability to the public, many media outlets from the University of Arkansas, Northwest Arkansas region, and localized newspapers throughout the country have exposed the development of the project. The team also plans to submit a manuscript for peer-reviewed publication in Control Engineering and received an invite to publish in MIT’s new online journal on project-based learning.

Conclusions:

Based on Phase I research, butanol production from algae has the potential to be a sustainable alternative fuel technology. Phase I made substantial progress towards successfully demonstrating the production of butanol from algae. A fully automated algae-to-butanol demonstration system was successfully designed, constructed, and operated. The team optimized many experimental parameters in the process. Future development of a continuous process instead of a batch process would improve the economic viability of the process. Based on the energy use analysis performed in Phase I, it is clear that the separation of butanol from the fermenter effluent is a critical step in improving the sustainability of the production process. Therefore more research is required to improve this technology. Phase II proposes to do this by building and optimizing a continuous unit (PEACE-2) that would serve as a potentially marketable unit in both developed and developing countries, serving to clean water, fuel society, and sustain life.

Supplemental Keywords:

Butanol, algae, macroalgae, Clostridium saccharoperbutylacetonicum, fermentation, ABE fermentation, alternative fuel, sustainability

Relevant Websites:

Planet Forward Exit