A breakthrough in the production of biofuel from marine algae could lead to a new ecnomically sustainable form of alternative energy.

Efficient algal biofuel production has long been stalled due to a catch-22 in the way algae grows and stores energy. The generally microscopic organisms largely produce the lipid oils, or fat molecules that store energy, needed for fuel production when they are nutritionally starved. However, when they are starved, they fail to grow well.

Researchers at Scripps Institution of Oceanography at the University of California, San Diego have developed a way to target a specific enzyme inside a group of algae known as diatoms, metabolically engineering a way to increase lipids without hurting growth.

The resulting genetically altered strains can be produced broadly in other species, the scientists say.

Graduate student Emily Trentacoste led the study, published by the Proceedings of the National Academy of Sciences. According to Trentacoste, the findings support the use of engineering in creating an answer to the question of lipid production that, for so long, has stalled research on the subject.

"These results demonstrate that targeted metabolic manipulations can be used to increase accumulation of fuel-relevant molecules.... with no negative effects on growth," Trentacoste said. "We have shown that engineering this pathway is a unique and practical approach for increasing lipid yields."

The study comes as world leaders gather in Warsaw for the United Nations Climate Change Conference. The UN has set the goal of preventing global temperatures from rising more than 2 degrees Celsius -- a goal that is becoming increasingly difficult to obtain in face of increased greenhouse gas emissions, researchers warn. A recent report released by the Global Carbon Project says global carbon emissions are expected to rise to a record high this year of 36 billion metric tons, putting 2013 global emissions from fossil fuels 61 percent above 1990 levels.

"Emissions must fall substantially and rapidly if we are to limit global climate change to below two degrees," said Corinne Le Quéré of the Tyndall Centre for Climate Change Research at the University of East Anglia, the lead author of the Global Carbon Budget report. "Additional emissions every year cause further warming and climate change."