Biofuels are fuels produced from living organisms or from metabolic byproducts (organic or food waste products). Most cars and trucks are fueled by gasoline and diesel fuels. Gasoline and diesel are actually ancient biofuels. But they are known as fossil fuels because they are made from decomposed plants and animals that have been buried in the ground for millions of years. Gasoline and diesel are nonrenewable fuels, as supplies will eventually run out. Biofuels are similar, except that they're made from plants grown today. In order to be considered a biofuel the fuel must contain more than 80 percent renewable materials. Biofuels are derived from the process of photosynthesis and can be called a solar energy source.
Biofuels have been around as long as cars have. At the start of the 20th century, Henry Ford planned to fuel his Model Ts with ethanol, and early diesel engines ran on peanut oil.
But discoveries of huge petroleum deposits kept gasoline and diesel cheap for decades, with biofuels largely forgotten. However, with the recent rise in oil prices, and growing concern about global warming caused by carbon dioxide emissions, biofuels have regained popularity.
Much of the gasoline in the United States is blended with a biofuel—ethanol. This is the same stuff as in alcoholic drinks, except that it's made from corn that has been heavily processed. There are various ways of making biofuels, but they generally use chemical reactions, fermentation, and heat to break down the starches, sugars, and other molecules in plants. The leftover products are then refined to produce a fuel that cars can use.
Countries around the world are using various kinds of biofuels. For decades, Brazil has turned sugarcane into ethanol, and some cars there can run on pure ethanol rather than as additive to fossil fuels. And biodiesel—a diesel-like fuel commonly made from palm oil—is generally available in Europe.
On the face of it, biofuels look like a great solution. Cars are a major source of atmospheric carbon dioxide, the main greenhouse gas that causes global warming. But since plants absorb carbon dioxide as they grow, crops grown for biofuels should suck up about as much carbon dioxide as comes out of the tailpipes of cars that burn these fuels. And unlike underground oil reserves, biofuels are a renewable resource since we can always grow more crops to turn into fuel.
Unfortunately, it's not so simple. The process of growing the crops, making fertilizers and pesticides, and processing the plants into fuel consumes a lot of energy. So much energy that a debate has begun about whether ethanol from corn actually provides more energy than is required to grow and process it. Also, because much of the energy used in production comes from coal and natural gas, biofuels don't replace as much oil as they use.
For the future, many think a better way of making biofuels will be from grasses and saplings, which contain more cellulose. Cellulose is the tough material that makes up plants' cell walls, and most of the weight of a plant is cellulose. Future cellulosic crops, like switchgrass, will have the added benefit of being able to grow on marginal soils not suited for traditional agriculture. Less than one percent of farmland globally is currently used to grow biofuels crops. If cellulose can be turned into biofuel, it could be more efficient than current biofuels, and emit less carbon dioxide.
Algae may be the most promising new idea in the search for a more environmentally friendly, mass-produced product that can be converted into fuel. Algae grow naturally all over the world. Under optimal conditions, it can be grown in massive, almost limitless, amounts. More than half of algae's composition, by weight, is lipid oil. Scientists have been studying this oil for decades to convert it into algae biodiesel.
Algae are easy to grow and can be manipulated to produce huge amounts without disturbing any natural habitats or food sources. Algae are easy to please -- all they need are water, sunlight and carbon dioxide.
During the algae biodiesel production process, algae consume carbon dioxide, through photosynthesis, and replace it with oxygen. For this reason, algae biodiesel manufacturers are building biodiesel plants close to energy manufacturing plants that produce lots of carbon dioxide. Recycling carbon dioxide reduces pollution.
Algae biodiesel production has the potential to outperform other potential biodiesel products such as palm or corn. For example, a 100-acre algae biodiesel plant could potentially produce 10 million gallons of biodiesel in a single year. Experts estimate it will take 140 billion gallons of algae biodiesel to replace petroleum-based products each year. To reach this goal, algae biodiesel companies will only need about 95 million acres of land to build biodiesel plants, compared to billions of acres for other biodiesel products. Since algae can be grown anywhere indoors, it's a promising element in the race to produce a new fuel.
The city of Venice has announced a plan to utilize algae biofuel. The Italian city plans to produce 50 percent of its electricity needs from an algae-based power plant instead of fossil fuels. ??The water-filled city is turning what has become a nuisance into a renewable energy resource. The city will be producing electricity from two types of algae that are brought in clinging to ships and regularly grow over the seaport. The algae will be cultivated and treated in laboratories to turn it into fuel. The fuel will then be used to power turbines in a new 40 MW power plant in the center of the city.
In order to make the new power plant truly carbon neutral, any CO2 produced by the process will be fed back to the algae. The innovative project will cost the city $264 million and should be operating in two years.
Congress passed energy legislation, known as the Energy Independence and Security Act of 2007, which raises standards for vehicle fuel economy and mandates that U.S. transportation fuel include 21 billion gallons of advanced biofuels by 2022 and 2 billion gallons as soon as 2012. The legislation further requires that these advanced biofuels must achieve at least a 50% reduction in life-cycle greenhouse gas emissions.
Biofuel is considered truly renewable because its source - biomass - is a replenishable resource. Vegetative matter will continue to grow as long as it is planted. Additionally, biomass energy recycles carbon dioxide during the plant photosynthesis process and uses it to make its own food. In comparison to fossil fuels such as natural gas and coal, which take millions of years to be produced, biomass is easy to grow, collect, utilize and replace quickly without depleting natural resources.
Greenhouse gas (GHG) emissions will decrease dramatically as biofuels of the future are increasingly made from cellulosic feedstocks and algae and as the associated farming, harvesting, transport, and production processes use progressively more clean, renewable energy sources.
U.S. Department of Energy studies show corn ethanol results in 19% fewer GHG emissions, on average, when compared with petroleum. Cellulosic ethanol has the potential to reduce GHG emissions by up to 86%. Algae biodiesel may reduce GHG emissions by 100%!
Environment.nationalgeopgraphic.com, ecogeek.org, Department of Energy