Calls to curb the world’s depen­dence on fossil fuels have grown louder in recent years, and sci­en­tists world­wide con­tinue to push for break­throughs in the green tech­nology industry. Last year, five North­eastern Uni­ver­sity engi­neering stu­dents found them­selves in the heart of this global issue—designing a low-​​cost biore­actor that pro­duces clean biofuels.

The stu­dents — Dave Chris­tianson, Eliz­a­beth Duffy, Bryan Keen, Andrew Maz­zotta, and Jameson Stark —were tasked with their senior cap­stone project by Joule Unlim­ited Inc., a Cam­bridge, Mass.-based firm. The company’s tech­nology involves col­lecting sun­light and waste carbon dioxide and con­verting it into clean, renew­able energy using spe­cially designed microbes. The process takes place in a biore­actor, where these engi­neered organ­isms syn­the­size and secrete liquid bio­fuels in large volumes.

Their project strongly aligns with Northeastern’s research mis­sion to solve global chal­lenges, with a focus on sus­tain­ability, health, and security.

It kind of encom­passed every­thing we’d learned over the years into one project, which was very appro­priate,” Chris­tianson said.

The cap­stone evolved out of a co-​​op Keen com­pleted at Joule in spring 2010. During his expe­ri­en­tial learning oppor­tu­nity, Joule offi­cials offered Keen the chance to design a lab-​​scale biore­actor that pro­vides an optimal envi­ron­ment for pro­ducing bio­fuels effi­ciently. The design had to allow for vari­a­tion of key para­me­ters such as light inten­sity, tem­per­a­ture, and sparging (intro­ducing air and carbon dioxide into the microbe cul­ture) so that var­ious envi­ron­mental set­tings can be used to test microbe productivity.

The final design was the result of months of hard work and col­lab­o­ra­tion to opti­mize each com­po­nent and bring them all together to devise an elab­o­rate, high-​​tech unit. “That’s what engi­neering is, making those little tweaks that make every­thing work,” Maz­zotta said.

The stu­dents said they also devel­oped a strong work ethic throughout the process, and as Jef­frey Ruberti — an asso­ciate pro­fessor of mechan­ical and indus­trial engi­neering who served as the stu­dents’ adviser — pushed them to back every­thing up with math and theory, their con­fi­dence grew.

This group did an amazing engi­neering job. They really dug in,” Ruberti said.

The mini-​​bioreactor project was truly mul­ti­dis­ci­pli­nary, requiring knowl­edge of fluid mechanics, heat transfer, mechan­ical design, optics, and instru­men­ta­tion, along with some biology. The stu­dents clearly worked hard and their resulting design is impres­sive,” said Stuart Jacobsen, an engi­neer at Joule.