LONDON - This year, Brazil produced 15 million tons of oranges. About 86% of those oranges were then turned into fresh orange juice. Imagine, then, the number of orange peels thrown away in Brazil. 

The orange-peel abundance in Brazil  is enough to attract attention from the British chemist James Clark, a professor at the Center for Green Chemistry at the University of York. Clark wowed the most recent British Science Festival by presenting a technique for converting orange peels into biofuel, using microwave energy. It is one of many research projects in the Old Continent attempting to develop biofuel in order to help reduce CO2 emissions.

Clark’s technology is part of a project called OPEC (Orange Peel Exploitation Company). The process consists of crushing the orange peels, putting them in a microwave that resembles a giant home oven, and activating the cellulose and other components with the microwaves. “The orange peel has an interesting chemical composition that makes it very easy to convert into fuel,” says Clark.

The European Union has contributed six million euros to the project. The Carbon Trust, a major British company that specializes in the renewal of carbon-based energy, and the University of São Paulo, have also collaborated. Now Clark and his group are working with a test processing unit, which allows them to process 30 kilos of orange peel (or other citrus peel) per hour.

Is It Really Worth It?

Between 1970 and 2009 Brazil doubled consumption of primary energy products such as oil and natural gas, while the country’s consumption of secondary energy products such as gasoline increased by a factor of five. In terms of CO2 emissions, the past decades have seen an increase of some 88%.

In addition to being the world’s leading producer of orange juice, Brazil is also one of the main providers of ethanol for biofuel. In 2010, it produced 2,600 million tons of ethanol, around 30.1% of total world production. Clark’s project suggests a potential convergence of the two industries. But, is that possible, viable or even recommendable?

Supporters and critics of biofuels disagree. A recent study by economists at Oregon State University concluded that all of the current biofuel projects currently in use in the United States reduce the use of fossil fuel by only 2.5%, and cost some $67 billion. The same reduction could be achieved by a 2.5% tax per gallon of gasoline, and would cost a tenth as much.

“The problem with first-generation biofuels, especially in Brazil, is that tropical forests are being cut down to accommodate the crops, and that results in a significant loss in biodiversity and natural habitat,” says Marvin Marcus, a scientist at the School of Biology of the University of Nottingham, who has worked on the Lignocellulosic Conversion to Ethanol (LACE) program, which focuses on producing ethanol from agricultural waste.

These biofuels, created from waste products, would be the second generation. Europe has her sights set on this second generation, particularly in the production of ethanol from waste straw. Although Marcus dismisses the idea that it is possible to create a technology that will not have environmental side effects, biofuel extracted from waste products would be a much more environmentally friendly product. 

Chilean-born Claudio Ávila, from the Department of Chemistry and Engineering at the University of York, agrees with Marcus about the environmental side effects of some biofuels, arguing that the indiscriminate use of resources for biofuel threatens food security and generates large areas of monoculture to satisfy the raw material needs for fuel production. However, Ávila maintains that these collateral damages will decrease “as the technology evolves, which depends on economic and social factors.”

Ávila says the main barrier to biofuel production in Latin American is the need for large investments, and the low long-term returns. However, he is confident that biofuels can provide for the energy needs of small communities that are far from large economies of scale. For example, the methane gas from the fermentation of garbage "could be a valuable source of energy for a small agricultural community that needs heat for homes and greenhouses,” Ávila says.

Cheap and mobile

Meanwhile, Clark defends his microwave technology precisely because of its low costs, and the fact that the orange peels do not require a refinery like those used for oil. The microwave machine is relatively small, and easy to move to wherever the waste is. “The largest microwave that I know of, which can work with 6 tons per hour, is only 5 or 6 meters long,” Clark says.

For Igor Polikarpov, professor at the Physics Institute of São Carlos, the use of orange peels as the raw material for biofuels is an interesting development. “But it is necessary to put in the equation a way to increase the added value with the available technologies. Limonene (the largest component in the oil found in orange peels), has a high added value. Using it as the raw material for the generation of biofuels will make the whole process much cheaper,” he says.

This reduction in price, Polikarpov says, is fundamental if the process if going to be commercially competitive. At the moment, the orange peels are used primarily as animal food, so almost any other use would end up being more profitable for the producers.

If the project comes to fruition, it is likely that your morning glass of orange juice will also help fill your gas tank.

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Photo - Mark Hillary