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Mark Edwards
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Much of the energy on Earth comes from the sun. Solar energy in ancient oceans was captured by algae and sank to the bottom of the water column. Over hundreds of millions of years, this rich sediment was fossilized into the energy we use today in fossil fuels. Unfortunately, recovering carbon and burning it causes climate change and all the well documented problems from too much carbon in Earth's atmosphere.

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Chemist Emma Kate Payne displays a fuel sample created from algae at LiveFuels in San Carlos, Calif. Behind the scenes, the airline industry is aggressively pushing for home-grown alternatives to petroleum-based jet fuel. Though supplies will not be ready for several years, a coalition that includes the United States Federal Aviation Administration, airline, manufacturing and airport associations wants standards for a 50-per-cent synthetic jet fuel approved by the end of the year. It’s just one of the possible applications for fuel made from farmed algae.

Green solar, also known as algaculture, uses solar energy and CO2 to produce carbon-neutral, clean energy quickly - in weeks. Green solar uses available carbon already in the atmosphere and water or reuses the CO2 from fossil fuel power plants or other sources. Green solar sequesters carbon in the green biomass of algae at the rate of about two pounds of CO2 per pound of algae. Algae produce about 60 per cent of the oxygen on Earth, more than all the forests and fields combined.

Algae are the oldest, tiniest yet fastest growing plants on earth. Algae are 30 to 100 times more productive in producing biomass than land plants because they waste no energy on physical structures such as roots, trunks, leaves and seeds. Water supports algae like a womb.

Algae use plentiful inputs - sunshine, wastewater, CO2 and a few nutrients - to convert solar energy to high-energy plant bonds. The algae biomass of lipids (oils), protein and carbohydrates may be 20 to 50 per cent oil. The oil may be pressed out of the biomass to create clean biodiesel (in the form of vegetable oil) that fuels diesel engines directly without requiring any mechanical conversion. U.S. Environmental Protection Agency tests show algal biodiesel reduces emissions by 79 per cent over petroleum diesel, produces almost no black soot or particulates and is renewable. The remaining carbohydrates may be refined to other biofuels and the protein separated for food or fodder for animals.

Green solar produces energy in a variety of ways for: people (protein in food); animals (protein in fodder); fowl (protein for birds); fish (protein in fish feed); plants (organic nitrogen fertilizer); fire (high energy algal oil for cooking and heating); cars (carbohydrates refined to gasoline for transportation); trucks and tractors (high energy green diesel); and planes (high energy aviation gas and jet fuel).

Green solar also produces other co-products, such as low-cost organic fertilizer and medicines, vaccines and pharmaceuticals. Algae communities also provide a wide range of pollution diagnostics, measures and air and water pollution solutions.

These water-based plants do not compete for precious fresh water because they can grow in wastewater, brine or saltwater. Green solar biofactories can grow algae anywhere on Earth where the sun shines - any altitude, latitude, longitude, climate or geography. In closed growing systems, they consume no cropland, no fresh water and no fossil fuels. They benefit from human, animal or industrial waste streams - free nutrients - and clean the water. Municipal waste systems have used algae ponds for decades to clean polluted water.

Algal communities grow quickly and may double or triple their biomass daily. The biomass grows when the sun shines, so solar or wind can provide the modest energy needed for mixing and moving water. Most algae prefer heat for optimal growth, but some species grow well in cold climates, even under glaciers on mountain tops and under the Antarctic ice. Canada is planning production systems that will use geothermal for heating biofactories in greenhouses.

Green solar may seem novel, but algae are actually nature's oldest strategy for growing food. This humble plant provided the first food on Earth, serving as the lowest rung on the food chain 3.5 billion years ago.

Green solar offers the fastest, cheapest and non-polluting solution for displacing liquid transportation fuels. Algae alone will not be the silver bullet for displacing fossil fuels, because the electrical grid will benefit from other carbon neutral energy sources such as solar, wind, waves, tides and geothermal. Green solar can replace fossil fuels with clean energy for liquid transportation fuels and promises novel, high-value carbon neutral solutions that benefit people globally.

Mark Edwards is Professor of Marketing and Sustainability at Arizona State University.