Work needed to make algal biofuel viable, study suggests

Jan 31, 2013 by Krishna Ramanujan
This photo shows oil being squeezed from the algae species, Botryococcus Braunii. B. Braunii is known for its production of oil, which converts relatively easily into gasoline and diesel. Credit: Arum Han/Texas A&M University

(Phys.org)—Though biofuels from algae hold great promise, Cornell researchers find that more innovation is needed to make the technology economically and energetically viable at a commercial scale.

To date, researchers have struggled to determine if the nonrenewable energy it takes to make a gallon of algal will be equal to, less than or greater than the energy produced.

A Cornell study published online Dec. 13 in the journal has addressed that question. The work was led by Deborah Sills, a postdoctoral associate in the research groups of Charles Greene, director of the and Ecosystems Program and professor of earth and atmospheric sciences, and Jefferson Tester, associate director for energy at the Atkinson Center for a and the Croll Professor of Sustainable Energy Systems in the School of Chemical and Biomolecular Engineering.

The researchers used to analyze uncertainties in the algal biofuel production lineup. They found that when oil is extracted from through thermal drying, or when the algal cultivation step has a low yield, the energy produced is less than the energy expended to produce the fuel. However, when methods that promote high algal yields are matched with wet extraction techniques—both processes that require further —algal biofuels can provide a viable alternative to liquid fossil fuels, like gasoline and diesel.

Compared with , algae can produce greater than 10 times more oil per acre, use nutrients more efficiently, and do not require high-quality . Also, do not require large quantities of freshwater.

The study examines each step in the process, from growing marine-based algae to separating and refining biofuel products and by-products. A life cycle framework helped establish ranges of possible outcomes with probabilistic methods employed to characterize key variables, which the authors say is the correct approach for assessing such developing technologies.

"Our biggest contribution is pointing out how important it is to report the range of values needed for technologies that don't exist," Sills said. "There is no algae to biofuel industry yet," so no large-scale sets of data exist to judge how feasible algal biofuels can be, Sills added. "We show that improvements are needed at every single step of the process."

"We've tried to be more transparent and reflect on the inherent variability and unknown character of the processes involved," Tester said.

Values reported in previous studies, while not incorrect, represented specific case studies and often reported findings as a single value. This yielded incomplete information for making strong conclusions about the viability of algal biofuels, the researchers said.

Making biofuels from algae is a five-step process: cultivation; harvesting and dewatering; lipid (oil) extraction; lipid conversion to liquid biofuel; and creating such value added co-products as methane from bio-digesters, or animal feed from leftover carbohydrates and proteins.

While all the steps require improvements, a few of the processes fared particularly poorly, according to the study. For example, all the scenarios studied failed to reach a break-even point when algae were grown with methods that had low yields of biomass. The cultivation phase involves growing algae in large open ponds with a mixer to expose algae to the sun. Fertilizers and carbon dioxide, potentially provided from industrial sources, are needed. Algal productivity depends on species, sun exposure, temperature, competing organisms, culture densities and nutrients.

Similarly, during the lipid extraction phase, no scenario supported a dry extraction process as an energetically viable option. Thermal drying requires too much energy, with solar drying alternatives requiring space. Wet lipid extraction using water under high temperatures and pressure produced the best results, especially when coupled with growing methods that produced high biomass, though those technologies have only been tested on small scales.

Explore further: US delays decision on Keystone pipeline project

Related Stories

Industrial production of biodiesel feasible within 15 years

Aug 13, 2010

Within 10 to 15 years, it will be technically possible to produce sustainable and economically viable biodiesel from micro-algae on a large scale. Technological innovations during this period should extend the scale of production ...

Recommended for you

US delays decision on Keystone pipeline project

Apr 18, 2014

The United States announced Friday a fresh delay on a final decision regarding a controversial Canada to US oil pipeline, saying more time was needed to carry out a review.

New research on Earth's carbon budget

Apr 18, 2014

(Phys.org) —Results from a research project involving scientists from the Desert Research Institute have generated new findings surrounding some of the unknowns of changes in climate and the degree to which ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

The Alchemist
1 / 5 (1) Feb 01, 2013
Can anyone debunk this one?
Cellulose (vegetable fiber) and enzyme decomposition becomes startch.
Starch plus 1,4 Gludosidasse becomes glucose.
Glucose plus yeast becomes etanol.
Ethanol becomes Carbon Neutral fuel and automobiles return to running on 100 octane (Ethanol) and not petrochemicals 80 octane).

More news stories

China says massive area of its soil polluted

A huge area of China's soil covering more than twice the size of Spain is estimated to be polluted, the government said Thursday, announcing findings of a survey previously kept secret.

UN weather agency warns of 'El Nino' this year

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...