The world today uses enough power to illuminate 150 billion light bulbs for a year. According to some estimates, by 2050, demand will double, creating irreversible climate change without reductions in humanity’s carbon output.

Improbably enough, your idle personal computer could play a big part in altering this outcome: Harvard chemist Alán Aspuru-Guzik has received a multiyear renewable grant from IBM to harness the power of idle desktop computers — a process known as distributed computing — to develop next-generation solar cells that might help satisfy the world’s future energy needs.

“The solution to the energy problem requires a combination of many different factors, including increasing the energy efficiency of all activities in our society, dramatically ramping up the use of all renewable energy sources, implementing carbon sequestration schemes in our coal plants, and enacting progressive carbon trading policies,” says Aspuru-Guzik, assistant professor of chemistry and chemical biology in the Faculty of Arts and Sciences, whose research group focuses on the development of novel materials for solar cells as a source of renewable local power generation.

Aspuru-Guzik is among scientists worldwide who are exploring more efficient ways to convert sunlight into electricity — “a process,” he says, “which would likely require less than 1 percent of the planet’s surface to meet that need.”

Commercially available solar cells are based on silicon semiconductor technology. But the specialized manufacturing process is expensive, meaning these cells have not been widely adopted. Currently, in most scenarios, burning coal is cheaper than using solar power.

Developing affordable solar cells based on organic molecules to harness the abundant power of the sun is the ultimate goal for Aspuru-Guzik and his team, which has partnered with the World Community Grid, a nonprofit initiative funded by IBM.

For many hours a day, the central processing unit of your personal computer sits unused. The goal of the World Community Grid is to utilize the processing power of individual computers during these idle times to find answers to global challenges such as cancer, famine, and human protein structure. Aspuru-Guzik’s Clean Energy Project will be one of only six currently working with the World Community Grid.

Aspuru-Guzik’s team is researching organic compounds for use in a new generation of solar cells. Atoms such as carbon, nitrogen, and oxygen molecules are the building blocks for these compounds, but they can be combined in countless ways. The difficulty lies in identifying which compound to use.

“The number of potential molecules that can be used in an organic solar cell is limited only by the imagination of the chemist,” Aspuru-Guzik explains.

Tens of thousands of different possible synthetic compounds must be tested. Rather than create them all in a laboratory, Aspuru-Guzik’s team is using cutting-edge computer programs to create a virtual laboratory to test and pinpoint the best candidates for future solar cell research. These massive calculations are greatly accelerated using the power of the World Community Grid.

After computer analysis identifies promising candidate molecules, they will be passed to experimental researchers for testing in real labs. Ultimately, with support from the World Community Grid, scientists hope to create efficient and inexpensive solar cells that will be part of the solution for the world’s growing energy needs.

Members of the Aspuru-Guzik research group who are spearheading this distributed computing effort are postdoctoral researcher Roel Sánchez-Carrera and graduate students Roberto Olivares-Amaya and Leslie Vogt.