For the average citizen, algae are often viewed as a problematic growth within backyard swimming pools and in-home fish tanks. In these settings the goal is to eliminate and prevent algae formation. On the other hand, algae as part of greenhouse gas emissions reduction efforts and biofuel production are hot topics. Algae support environmental improvement (via carbon dioxide sequestration) and alternative fuel needs, which are the most acute demands in the current market.

In addition to ethanol projects, the electric utility sector is strongly interested and now testing the injection of hot flue gas from coal- and natural gas-fired power plants with plans for carbon sequestration. Certain blue-green algae can grow in an environment with hot flue gas from power or chemical projects. Via photosynthesis, carbon dioxide and water are basic requirements for algae growth, and oxygen and water vapor are byproducts. The algae also can absorb sulfur dioxide and nitrogen oxides, which are two compounds that cause acid rain. The algae process from power, combustion and other chemical projects including ethanol are therefore a means of sequestering carbon.

Conceivably, a full-loop system could be created where ethanol production yields the byproduct carbon dioxide, which is used to grow algae. The algae can then be used in the manufacturing of biodiesel and/or as a feedstock for fermentation into ethanol. The algae growth creates a carbon dioxide sink, which is extremely important, as it would be generating a viable, highly efficient form of plant oil from algae. Algae are the most viable plant oil source available, growing more rapidly than any other material. As a rule of thumb, approximately one ton of carbon dioxide is removed from otherwise airborne emissions via the growth of two tons of algae.


A flow chart depicting carbon dioxide-to-algae-to-biodiesel production
SOURCE: SAM RUSHING, ADVANCED CRYOGENICS LTD.

Gross Yield, Markets
Merchant carbon dioxide is well known as a soft drink carbonation agent, a cryogenic fluid and an industrial gas consumed in foundries, to name a few applications. An estimated 25 million tons of carbon dioxide emissions are absorbed daily by the oceans. Fifty million gross tons of excess carbon dioxide is beyond the ocean's ability to absorb the gas in a natural process.

This is coupled with the world's growing energy demands. Several U.S. groups are striving for energy independence. Even in markets that are oil-rich, carbon dioxide sinks must be established that are of a viable nature versus those that are not true sequestration methods, such as enhanced oil recovery. Using carbon dioxide from ethanol sources as an ingredient for algae growth is an excellent carbon dioxide sink since algae oil can then be used to produce biodiesel. Approximately 40 percent of the U.S. merchant carbon dioxide is sourced from ethanol versus other sources. The ethanol markets in the United States and Brazil are similar. However, corn-based ethanol sources run year-round versus those sourced from sugarcane in Brazil. The problem with Brazilian sources, if dedicating them to algae production, a chemical process or merchant markets, is it yields a void period associated with sugarcane crops and lacks a viable means for storage of sugarcane versus corn.

Unfortunately, corn has gained a bad reputation in terms of creating food shortages and high food prices, which is in error. Since the majority of corn is dedicated to markets other than ethanol, those worrying about grain use as a feedstock are seeking alternate feedstocks, such as algae. In reality, ethanol is today's primary hope to become energy independent in the United States and elsewhere.

Biodiesel Growth, Feedstock Yield and Projects
Algae have basic requirements for growth, including carbon dioxide, water, nutrients and sunlight. Carbon dioxide is a major byproduct of ethanol production. This article primarily discusses the biodiesel sector, where on the front end, carbon dioxide is one ingredient for algae growth and algae is perhaps the ultimate source of plant-based oil for biodiesel. It is also well known that algae can flourish in otherwise hostile growing environments, including non-arable land or dirty water. When algae flourish, they are unmatched by any known terrestrial feedstock. Algae can double in mass several times daily.

In the United States, Texas has traditionally been one of the largest biodiesel producers with more than 20 plants. In June, GreenHunter Energy opened one of the largest biodiesel plants in the United States, with optimal plans for 105 MMgy in capacity. However, this plant is utilizing animal fats and vegetable oils as feedstock. With respect to estimating the number of U.S. gallons of biodiesel produced from a variety of feedstock materials, algae is considered to be perhaps the highest in efficiency when compared to a variety of other materials. For example, the table below has estimates which are defined in terms of gallons of biodiesel per acre.

The U.S. DOE estimates that algae-based biodiesel can yield up to 30 times more energy per acre than crops such as soybean. A growing consensus suggests that biodiesel produced from algae is the only feasible solution today for full replacement of petroleum diesel products. No other feedstock has the oil yield sufficient in volume to produce such large volumes of oil.

To illustrate this point, in order to produce sufficient oil for biodiesel from crops such as soy or palm, all growing regions for all of today's crops would have to produce soy to yield sufficient biodiesel for full replacement versus producing a mix of biofuel, the ideal algae strains and food-dedicated products. Given the high oil yield from algae, some 10 million acres of land, pond or ocean would be sufficient to grow enough algae to replace the total petroleum diesel fuel in the United States. This is about 1 percent of the 1 billion acres used in the United States for grazing and farming.

One could conclude that algae are the vastly superior biodiesel feedstock material for the large-scale replacement of petroleum diesel. In order to produce large-scale quantities of algae for such massive biodiesel projects, it is essential to have sustainable, high oil-producing strains of algae on a large-scale basis. Then there must be the ability to adequately extract the oil from algae on a large scale. Finally, there must be the capability to convert algae oil into biodiesel. The first two steps are essentially specific to algae.

The final step is typical of all biodiesel processes related to all plant-based oils. The challenges of greatest need are defining and refining the most viable strains of algae strains and developing/maintaining the most effective and optimal cultivation methods.

Petro Sun announced an algae-to-biofuel plant in Rio Hondo, Texas. The company expects to operate a 1,080-acre farm with an additional 20 acres for jet fuel. The micro algae production is said to yield 30 times more energy per acre than corn or soybeans. Internationally, Tel Aviv, Israel-based Seambiotic plans to use recycled carbon dioxide. The carbon sequestering venture sourced from a power plant is a feedstock for the algae, which ultimately is planned to yield ethanol and biodiesel and sequester carbon dioxide.

Since algae can grow under severe conditions, a wide range of temperatures, pH and salinity, such biodiesel facilities can exist in places that are fully unsuitable for conventional agriculture. Again, key technical challenges are the right strains of algae with the highest oil content.

Summary
Algae can grow at rates many times beyond the alternate forms of plant-based oil derivatives, which in turn can be used as a feedstock for biodiesel production. Algae can grow in a wide variety of climates, in a wide range of terrain, and yield the most plentiful form of plant oil feedstock for biodiesel. This is an extraordinary opportunity for replacement of diesel and jet fuels from biodiesel plants. These oil replacement agents are the key to long-term self sufficiency and energy management for the future. n

Sam A. Rushing is with Advanced Cryogenics Ltd. Reach him at rushing@terranova.net or (305) 852-2597.