Algae biofuels have been touted as being capable of mass-producing liquid fuels more sustainably than ethanol, soy biodiesel or any of the various biomass, waste or fossil-derived liquid fuel schemes. Algae biofuels can be grown in fresh or salt-water, can be grown in self-contained ponds, and can theoretically meet U.S. diesel needs using only 1-3 million acres of land (about 2-5% of the currently fallow cropland in the U.S. and less than the size of the state of Connecticut). Diesel is 20% of our nation's petroleum demand, so an area about five times the size of Connecticut could meet all of our oil demand. Algae feeds on CO2.
Sounds great?
That's not the full story.
Algae biofuels have been explored for decades, with more attention in the past decade. Fundamental problems keep it from making sense... mainly the need for a concentrated CO2 source and large amounts of water and nutrients (nitrogen and phosphorous). Many of these problems are discussed in the 2017 Biofuelwatch report, Algenol: Case Study of an Unsuccessful Algae Biofuels Venture. See also: Hard Lessons From the Great Algae Biofuel Bubble (2017 article in Green Tech Media on the lack of progress in making algae biofuels work)
One problem with commercially producing biodiesel from algae is that it needs a concentrated and plentiful CO2 source. This requires hitching this "green" industry to dirty pollution sources that ought to be rapidly phased out, such as coal power plants. This marriage of algae biodiesel to coal has resulted in such public relations articles with titles like "Algae - like a breath mint for smokestacks." To obtain a purified CO2 source from power plant exhaust, massive amounts of investment dollars would need to be spent on "clean coal" gasification systems – perpetuating coal use (and the related destruction from mining, burning and waste disposal). Such money would go much further if invested in genuine clean energy strategies.
To make the industry commercially viable, researchers have pursued biotech varieties, which could be particularly dangerous if released into nature. Some algae biodiesel proposals involve aquaculture-style operations in open ocean waters, which could have harmful ecological effects, especially if biotech algae is used.
Water and nutrient use would also be extreme, making any serious scaling up of algae biofuels quite unsustainable.
The National Research Council of the National Academy of Sciences has explored this in a 2012 report called "Sustainable Development of Algal Biofuels," which found the following:
Biofuels made from algae are gaining attention as a domestic source of renewable fuel. However, with current technologies, scaling up production of algal biofuels to meet even 5 percent of U.S. transportation fuel needs could create unsustainable demands for energy, water, and nutrient resources. Continued research and development could yield innovations to address these challenges, but determining if algal biofuel is a viable fuel alternative will involve comparing the environmental, economic and social impacts of algal biofuel production and use to those associated with petroleum-based fuels and other fuel sources. This report was produced at the request of the U.S. Department of Energy.
Key Findings
- Based on a review of literature published until the authoring of this report, the committee concluded that the scale-up of algal biofuel production sufficient to meet at least 5 percent of U.S. demand for transportation fuels would place unsustainable demands on energy, water, and nutrients with current technologies and knowledge. However, the potential to shift this dynamic through improvements in biological and engineering variables exists.
- Sustainable development of algal biofuels would require research, development, and demonstration of the following:
- Algal strain selection and improvement to enhance desired characteristics and biofuel productivity.
- An energy return on investment (EROI) that is comparable to other transportation fuels, or at least improving and approaching the EROIs of other transportation fuels.
- The use of wastewater for cultivating algae for fuels or the recycling of harvest water, particularly if freshwater algae are used.
- Recycling of nutrients in algal biofuel pathways that require harvesting unless coproducts that meet an equivalent nutrient need are produced.
- A national assessment of land requirements for algae cultivation that takes into account climatic conditions; freshwater, inland and coastal saline water, and wastewater resources; sources of CO2; and land prices is needed to inform the potential amount of algal biofuels that could be produced economically in the United States.
- Algal biofuels have the potential to contribute to improving the sustainability of the transportation sector, but the potential is not yet realized. Additional innovations that require research and development are needed to realize the full potential of algal biofuels.
- Algal strain development is needed to enhance traits that contribute to increasing fuel production per unit resource use, reducing the environmental effects per unit fuel produced, and enhancing economic viability. Improvements in biomass or product (lipid, alcohol, or hydrocarbons) yield, culture density, nutrient uptake, ease of harvest, and photosynthetic efficiency are some of the improvements that would improve sustainability of algal biofuels.
- Engineering solutions to enhance algae cultivation, to facilitate biomass or product collection, and to improve processing of algae-derived fuels can increase the EROI and reduce the GHG emissions of algal biofuel production.
The environmental, economic, and social effects of algal biofuel production and use have to be compared with those of petroleum-based fuels and other fuel alternatives to determine whether algal biofuels contribute to improving sustainability. Such comparison will be possible only if thorough assessments of each step in the various pathways for algal biofuel production are conducted.
BY GLOBAL JUSTICE ECOLOGY PROJECT | OCTOBER 24, 2012 · 11:05 AM
Note: The following is an overview of an upcoming report from the National Research Council. The concerns raised over large-scale algal biofuel production are serious, and highlight the dangers of many false solutions to climate change: increased use of essential resources (i.e., fresh water, land), dependence on synthetic or mined inputs such as nitrogen and phosphorus, and complete obscurity as to whether or not the technology will result in decreased carbon emissions. Further, as the below article notes, genetic engineering, or “strain improvement,” is needed to increase the efficiency and productivity of algae. Given the threats that GMO food crops and GE trees pose, the last thing we need is GE algae colonizing our rivers, lakes and oceans. Eventually, we will have to realize that the only viable substitute for fossil fuel use is a drastic decrease in our consumption patterns and systemic transformation of the current neoliberal economic system.
-The GJEP Team
October 24, 2012. Source: National Research Council
WASHINGTON — Scaling up the production of biofuels made from algae to meet at least 5 percent — approximately 39 billion gallons — of U.S. transportation fuel needs would place unsustainable demands on energy, water, and nutrients, says a new report from the National Research Council. However, these concerns are not a definitive barrier for future production, and innovations that would require research and development could help realize algal biofuels’ full potential.
Biofuels derived from algae and cyanobacteria are possible alternatives to petroleum-based fuels and could help the U.S. meet its energy security needs and reduce greenhouse gas emissions, such as carbon dioxide (CO2). Algal biofuels offer potential advantages over biofuels made from land plants, including algae’s ability to grow on non-croplands in cultivation ponds of freshwater, salt water, or wastewater. The number of companies developing algal biofuels has been increasing, and several oil companies are investing in them. Given these and other interests, the National Research Council was asked to identify sustainability issues associated with large-scale development of algal biofuels.
The committee that wrote the report said that concerns related to large-scale algal biofuel development differ depending on the pathways used to produce the fuels. Producing fuels from algae could be done in many ways, including cultivating freshwater or saltwater algae, growing algae in closed photobioreactors or open-pond systems, processing the oils produced by microalgae, or refining all parts of macroalgae. The committee’s sustainability analysis focused on pathways that to date have received active attention. Most of the current development involves growing selected strains of algae in open ponds or closed photobioreactors using various water sources, collecting and extracting the oil from algae or collecting fuel precursors secreted by algae, and then processing the oil into fuel.
The committee pointed out several high-level concerns for large-scale development of algal biofuel, including the relatively large quantity of water required for algae cultivation; magnitude of nutrients, such as nitrogen, phosphorus, and CO2, needed for cultivation; amount of land area necessary to contain the ponds that grow the algae; and uncertainties in greenhouse gas emissions over the production life cycle. Moreover, the algal biofuel energy return on investment would have to be high, meaning more energy would have to be produced from the biofuels than what is required to cultivate algae and convert them to fuels.
The committee found that to produce the amount of algal biofuel equivalent to 1 liter of gasoline, between 3.15 liters to 3,650 liters of freshwater is required, depending on the production pathway. Replenishing water lost from evaporation in growing systems is a key driver for use of freshwater in production, the committee said. In addition, water use could be a serious concern in an algal biofuel production system that uses freshwater without recycling the “harvest” water.
To produce 39 billion liters of algal biofuels, 6 million to 15 million metric tons of nitrogen and 1 million to 2 million metric tons of phosphorus would be needed each year if the nutrients are not recycled, the report says. These requirements represent 44 percent to 107 percent of the total nitrogen use and 20 percent to 51 percent of the total phosphorus use in the U.S. However, recycling nutrients or utilizing wastewater from agricultural or municipal sources could reduce nutrient and energy use, the committee said.
Another resource that could limit the amount of algal biofuels produced is land area and the number of suitable and available sites for algae to grow. Appropriate topography, climate, proximity to water supplies — whether freshwater, inland saline water, marine water, or wastewater — and proximity to nutrient supplies would have to be matched carefully to ensure successful and sustainable fuel production and avoid costs and energy consumption for transporting those resources to cultivation facilities. If the suitable sites for growing algae are near urban or suburban centers or coastal recreation areas, the price of those lands could be prohibitive. A national assessment of land requirements for algae cultivation that takes into account various concerns is needed to inform the potential amount of algal biofuels that could be produced economically in the U.S.
One of the primary motivations for using alternative fuels for transportation is reducing greenhouse gas emissions. However, estimates of greenhouse gas emissions over the life cycle of algal biofuel production span a wide range; some studies suggest that algal biofuel production generates less greenhouse gas emissions than petroleum-based fuels while other studies suggest the opposite. These emissions depend on many factors in the production process, including the amount of energy needed to dewater and harvest algae and the electricity sources used.
The committee emphasized that the crucial aspects to sustainable development are positioning algal growth ponds close to water and nutrient resources and recycling essential resources. With proper management and good engineering designs, other environmental effects could be avoided, the committee said. Examples include releasing harvest water in other bodies of water and creating algal blooms and allowing harvest water to seep into ground water.
For algal biofuels to contribute a significant amount of fuels for transportation in the future, the committee said, research and development would be needed to improve algal strains, test additional strains for desired characteristics, advance the materials and methods for growing and processing algae into fuels, and reduce the energy requirements for multiple stages of production. To aid the U.S. Department of Energy in its decision-making process regarding sustainable algal biofuel development, the committee proposed a framework that includes an assessment of sustainability throughout the supply chain, a cumulative impact analysis of resource use or environmental effects, and cost-benefit analyses.
The report was sponsored by the U.S. Department of Energy. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. They are private and independent nonprofit institutions that provide science, technology, and health policy advice under an 1863 congressional charter. Panel members, who serve pro bono as volunteers, are chosen by the Academies for each study based on their expertise and experience and must satisfy the Academies’ conflict-of-interest standards. The resulting consensus reports undergo external peer review before completion. For more information, visit http://dels.nas.edu/Report/Sustainable-Development-Algal-Biofuels/13437