Related Links


Algae – an annoying growth, or green bioenergy gold?

Sam A. Rushing - Advanced Cryogenics, Ltd

For the average citizen, algae is often viewed as a problematic growth within backyard swimming pools and in-home fish tanks. However in terms of reducing greenhouse gas emissions such as CO2 and a potential biofuel, algae is a hot topic.

In addition to ethanol projects, the electric utility sector is strongly interested in, and now testing, the injection of hot flue gas from coal and gas fired power plants. Certain blue-green algae can grow in an environment with hot flue gas from such power or chemical projects. The algae feed on water and carbon dioxide (CO2), and can also can absorb the acid rain chemicals SOx and NOx – the biproducts could be used for ethanol and biofuel production.

Carbon dioxide – gross yield, markets, and ethanol

Merchant CO2 is well known as a soft drink carbonation agent, a cryogenic fluid, and an industrial gas consumed in foundries, to name a few. Globally, there is an estimated 25 million tons of total CO2 emissions daily absorbed by the oceans, leaving a gross 50m tons in excess, beyond the ocean’s ability to take on this gas as a natural process, again this is on a daily schedule, all produced from industrial and biological processes. This is primarily power plant flue gas & chemical by-product; to follow with a wide range of other processes daily. This total 50m tons of carbon dioxide in excess each day is growing at an astronomical rate, from an emissions perspective.

Next is the question of growing energy demands. The USA has a dire need to become energy independent, as well as other continents and countries throughout the globe. Even in markets which are oil rich, CO2 sinks must be established which are of a viable nature, v. those which are not true sequestration methods, such as enhanced oil recovery (EOR). Using CO2 from ethanol sources as an ingredient for algae growth could be an excellent CO2 sink, since algae oil can be used to produce biodiesel.

Some 40% of the US merchant CO2 is sourced from ethanol in the USA. The US Midwest is today well satisfied with merchant CO2 from ethanol, assuming all current CO2 from ethanol sources continue. Other regions of the USA and various global markets are also candidates for CO2 from ethanol; that being for merchant use. As for algae use, all regions are wide open when ethanol and CO2 emitting sources exist.

The ethanol markets in the USA and Brazil essentially equal each other in terms of volume, however, corn based ethanol sources run year round versus those sourced from sugar cane, as found in Brazil.

The problem with the sources in Brazil, if dedicating these sources to the algae production – a chemical process – or the merchant markets, yield a void period due to the timing associated with sugarcane crops as well as the lack of a viable means for storage of sugarcane versus corn. Unfortunately, corn has gained a bad rap in terms of contributing to food shortages and high food prices; which is highly 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 feedstock, such as algae. In reality, ethanol is today’s primary hope to become energy independent in the USA, and elsewhere.

Biodiesel growth, feedstock yield & projects

It is well known that algae can flourish in otherwise hostile growing environments, including non-arable land, or in dirty water. When algae flourishes, it is unmatched by any terrestrial feedstock known.

Algae can double in mass several times daily. In the USA, Texas has traditionally been the largest producer of biodiesel; with well over 20 plants – and growing. In June 2008, GreenHunter Energy opened the largest biodiesel plant in the USA, with optimal plans for 105m GPY in capacity; however, this plant is utilising animal fats and vegetable oils as feedstock, with zero emissions resulting from the process.

Of course, B100 as 100% biodiesel is more expensive than diesel; so the most common form of biodiesel is 20% by volume, or more commonly known as B20. With respect to estimating the number of US 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 (gpa).

Table 1 – feedstock yield from acreage of crop source


YIELD – gpa



Tallow, Chinese


Palm Oil












The Department of Energy (DoE) estimates that algae fuel can yield up to 30 times more energy per acre than land crops such as soybean. A growing consensus suggests that biodiesel produced from algae is the only feasible solution today for replacement in full of petro-diesel products. No other feedstock has the oil yield sufficient in volume to produce such large volumes of oil.

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 simply soy (for example) to yield sufficient biodiesel for full replacement. Given the high oil yield from algae, some 10m acres would be sufficient, as land, pond, or ocean space, to grow enough algae to replace the total petro-diesel fuel in the USA today. This is about 1% of the total amount of acreage used in the USA for grazing and farming; that being about 1% of one billion acres.

In the end, one could conclude that the vastly superior biodiesel feedstock material for the large scale replacement of petro-diesel is clearly algae. 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; followed by the ability to adequately extract the oil from algae on such a scale. To follow, of course, there would need to be capabilities to convert algae oil into biodiesel. The first two steps are essentially specific to algae; and 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.

Announced as the first algae to biofuel plant domestically is in Rio Hondo, Texas, Petro Sun operating a 1080 acre farm with an additional 20 acres for jet fuel. The micro algae operation is said to yield 30 times more energy per acre than corn or soy. Numerous international projects, include the Tel Aviv-based Seambiotic project, to use recycled CO2 in the process. The carbon sequestering venture sourced from a power plant is a feedstock for the algae, which ultimately is planning to yield ethanol and biodiesel at the same time as sequestering CO2.

Converting vegetable, plant, and algae oil into biodiesel is largely defined as transesterfication. Since algae can grow under severe conditions, a wide range of temperatures, pH, and salinity; such facilities can exist in places which are fully unsuitable for conventional agriculture. Again, key technical challenges are the right strains of algae with the highest oil content (oil or lipid content from algae can be converted into diesel or jet fuels by conventional oil refineries); also harvesting efficiently such algae is the other challenge with this feedstock.


As described in this article, algae is the most efficient means of producing a unique agricultural crop with a high vegetable oil content versus petroleum products; as well as oils from other well known and tested food crops including as palm oil and soy crops. Moreover, algae does not take from foodstuffs, as would be what the press, the oil companies, and the lawmakers now are claiming is the reason for high food prices when using corn in ethanol production. Food prices today, being sky high are driven by high energy prices, and today.

The best hope for biofuels is a full range of feedstocks for ethanol, including the traditional corn, wheat, rice, and other grains used throughout history; however, today, and tomorrow, we can further balance this supply equation with the development of viable cellulostic technologies, as well as a growing use of algae as a feedstock in the production of biofuels.

When considering the so-called loop obtained when producing ethanol and the CO2 by-product feeding some of the essential processes whereby via photosynthesis the basic elements including light, CO2, water and nutrients yield fast growing strains of algae. Algae can grow at geometric rates; many times beyond the alternate forms of plant based oil derivatives, which in turn can be used as a feedstock material for ethanol as part of the loop back to ethanol; or perhaps more importantly a feedstock agent in the form of oils for biodiesel production.

In the end, 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 anywhere. This is an extraordinary opportunity for replacement of diesel and jet fuels from biodiesel plants; and from ethanol plants, the ethanol – petrol mix can use algae as a supplement or common feedstock. These oil replacement agents are the key to long term self sufficiency and energy management for the future; and algae can be the key.

About the author
Sam A. Rushing, of Advanced Cryogenics, Ltd. is a chemist with 30 years in the CO2 industry, in both merchant and consultant roles. A full range of services are available from technical to market and business services. Call or send an e-mail to 305 852 2597; ;

Share this article

More services


This article is featured in: