Synthetic biology is a rapidly growing field that is using engineering principles to design and build new biological systems. This technology has the potential to revolutionize a wide range of industries, including the aviation industry.
The rapid increase in greenhouse gas (GHG) emissions due to the extensive use of fossil resources have necessitated the production of renewable energy sources to sustain current economic activities while reducing net carbon dioxide emission.
Conventional hydrocarbon fuels are produced by distillation of crude oil. This process generates a variety of products including gasoline, diesel, and jet fuel. However, these distillates include sulfur-containing and aromatic compounds that can lead to acid rain, engine corrosion, and particulate formation. This leads to lower performance and increased maintenance costs for the Military.
Then there are synthetic fuels, which are produced by combining specific petrochemical molecules to generate fuel mixtures. Fuels of this type are typically expensive and methods to generate them can be carbon inefficient and energy-intensive.
Hydrazine-based propulsion systems are state-of-the-art for various applications ranging from launchers to large and small satellites. They have a long and successful heritage and a great variety of space-qualified, off-the-shelf components. Hydrazine has dominated the space industry as the choice of propellant for over six decades, due to its high-performance characteristics, despite its environmental and health hazards and the challenges faced in its manufacturing, storage, ground handling, and transportation.
Space agencies are trying to replace the conventional hydrazine rocket fuel, a highly toxic and carcinogenic chemical, with a greener propellant for future missions. These technologies present performance benefits such as reduced launch mass, increased scientific payload mass, and/or extending on-orbit lifetimes. The advantages are further reinforced due to the significant reduction in health risks encountered during launch site and ground handling operations.
One of the most promising applications of synthetic biology in aviation is the production of biofuels. Biofuels are made from renewable resources, such as plants and algae, and they can be used to power aircraft. Biofuels have the potential to reduce the environmental impact of aviation by reducing greenhouse gas emissions.
Biofuels are fuels, which are chemically similar to gasoline and diesel, but are produced by processing crops, algae or microbial culture. The carbon in biofuels comes from carbon dioxide that plants convert to their biomass through photosynthesis. Traditional biofuels are produced from food crops. This approach is costly and competes with food production in the use of land, water, energy, and other environmental resources. Through the use of synthetic biology it has become possible to engineer microbial cell factories for efficient biofuel production in a more precise and efficient manner.
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Synthetic biology is revolutionizing the production of biofuels for jet and diesel engines, paving the way for greener biomanufacturing processes.
By combining biology, engineering, and computer science, scientists are engineering microorganisms to produce specific molecules that can be converted into biofuels. This interdisciplinary approach allows for the design and construction of new biological systems or the modification of existing ones, enabling the optimization of fuel production pathways.
In the aviation industry, synthetic biology is helping to address the carbon emissions associated with jet engines. Researchers are developing biofuels tailored for aviation that meet stringent standards. By genetically engineering microorganisms, they can optimize the production of fatty acids or isoprenoids, which can be converted into renewable jet fuels. This approach enables the sustainable production of biofuels with properties that match or exceed those of traditional fossil fuels.
Diesel engines are also benefiting from synthetic biology advancements in biofuel production. Biodiesel, a renewable alternative to petroleum-based diesel, can be produced from various feedstocks, including algae, plant oils, and waste fats. Through synthetic biology techniques, scientists can optimize the conversion of these feedstocks into fatty acid methyl esters (FAME), the primary components of biodiesel. By modifying the genetic makeup of microorganisms, they can enhance the yield, quality, and compatibility of biodiesel with existing diesel engines.
The engineering of microorganisms plays a crucial role in biofuel production through synthetic biology. Researchers utilize tools such as genome editing and metabolic engineering to modify the genetic pathways responsible for fuel synthesis. This fine-tuning allows for the optimization of microorganisms’ ability to efficiently convert feedstocks into desired fuel molecules. Through targeted genetic modifications, scientists can enhance the production efficiency and yield of biofuels, making the process more economically viable.
Biomanufacturing relies on bacteria and other microorganisms with modified DNA to produce materials that are costly or impossible to obtain otherwise, including high-energy chemical compounds used in explosives. Researchers have used the tools of synthetic biology to manipulate the genes of Escherichia coli, a common gut bacterium, so that it can chew up vegetation to produce diesel and other hydrocarbons.
Synthetic biologists are attempting to get heterotrophic microbes (ones that can’t make their own food with photosynthesis but instead need to be fed with organic compounds) to convert the biomass from plants into usable fuels. Creating biofuels this way would then involve a two-step approach in producing the fuel, where plants are first engineered to grow as quickly as possible and then are ground up and fed to E. coli, yeast, etc., that would convert that biomass into ethanol and other fuels.
The efforts to produce corn ethanol with engineered yeast have become popular recently, and can be considered an extension of what beer and malt brewers have been doing for centuries. Synthetic biology aims to make this process many fold more efficient and better suited for fuels, like octane, that can be used to run existing gasoline engines much more efficiently than ethanol can, which is crucial in making the transition from a fossil fuel to a biofuel-based society as easily as possible.
E. coli is popular in genetic engineering because it is deeply studied and quite hardy, able to tolerate genetic changes well, says chemical engineer Jay Keasling of the University of California, Berkeley. Researchers have already modified E. coli to make medicines and chemicals, and now Keasling and his colleagues have turned the organisms into biodiesel factories.
The scientists first genetically modified E. coli to consume sugar and secrete engine-grade biodiesel, which can float to the top of a fermentation vat—no need for distilling, purifying or breaking cells open to get the oil out, as is the case for making biodiesel from algae.
The use of biosynthetic fuels in jet and diesel engines can decrease costs, increase the range and fuel economy of aircraft, ground vehicles and ships, while reducing the emission of toxic particulates and resulting in lower net greenhouse gas emissions.
Biofuels could be made from bacteria that grow in seawater, reported in Oct 2019
Researchers at The University of Manchester, supported by the Office of Naval Research Global (ONR), are utilizing synthetic biology to develop a more efficient method for producing bio-based jet fuels. Their approach involves using a type of bacteria called Halomonas, which naturally grows in seawater, as a “microbial chassis” that can be genetically engineered to produce high-value compounds. By re-engineering the microbe’s genome, the researchers aim to create renewable alternatives to crude oil and generate biofuels economically using production techniques similar to those used in the brewery industry, with seawater and sugar as renewable resources.
The breakthrough lies in the ability to modify the metabolism of the Halomonas bacteria, allowing it to produce different types of high-value chemical compounds, including bio-based jet fuel. Dr. Benjamin Harvey and his team at the Naval research facilities in China Lake, California, have been at the forefront of this research, pioneering the conversion of biological precursors into relevant jet fuels.
According to Professor Nigel Scrutton, Director of the Manchester Institute of Biotechnology, large-scale production of biofuels necessitates the use of robust microbial hosts cultivated on renewable waste biomass or industrial waste streams. The use of Halomonas fulfills these requirements, minimizing both capital and operational costs associated with the production of next-generation biofuels. Moreover, the jet fuel intermediates produced through this method are chemically identical to petrochemical-derived molecules, enabling their seamless integration into existing processes.
The implications of this research are significant for the biofuels industry as it presents a promising pathway towards more sustainable and economically viable bio-based jet fuels. By leveraging the capabilities of synthetic biology and harnessing the potential of bacteria found in seawater, researchers are paving the way for the development of renewable alternatives to traditional crude oil-based fuels.
BioFuel Alternative for Missile Fuel
Military researchers are exploring the use of E.coli bacteria to produce biofuel for Hellfire missiles, as part of a larger effort to manufacture specialty chemicals using microbes in a cost-effective and environmentally friendly manner. The initiative aims to reduce the military’s reliance on chemicals derived from crude oil, which are often obtained from limited suppliers and costly petrochemical facilities. By leveraging biomanufacturing capabilities, the U.S. Army seeks to become more self-sufficient and decrease the financial and environmental costs associated with traditional manufacturing processes.
Led by Peter Emanuel, the senior research scientist for bioengineering at the Combat Capabilities Development Command Chemical Biological Center, the biomanufacturing initiative represents a manufacturing revolution with the potential to position the United States as a competitor to China in the realm of superpower manufacturing technology. In addition to enhancing national security, the growth of the bioindustrial sector can provide economic benefits and promote sustainable manufacturing practices.
The Army’s biomanufacturing facility utilizes large steel vats to cultivate the microbes necessary for fermenting liquids, resembling the process used in microbreweries. The production of biofuel for Hellfire missiles will serve as a significant proof-of-concept project for the expanded and upgraded facility located at Aberdeen Proving Ground, Maryland. This endeavor will address an immediate defense need, as the facility will produce the chemical precursor, known as BT, used in Hellfire missile fuel. Currently, the Defense Department relies on a single U.S. supplier for BT, making it crucial to establish an alternative domestic source.
The Hellfire missile is the preferred weapon for precision strikes on high-value targets, and its widespread use necessitates a stable and reliable fuel source. But traditional manufacturing costs make it “economically infeasible” to use more than 15,000 pounds of BT a year in BTTN production, Navy-funded researchers at Michigan State University found in a 2007 report. To reach desired production levels, the costs would have to be driven down two-thirds to about $15 a pound. The Michigan State researchers used genetically engineered E.coli and fiber from corn hulls to produce half a liter of a 99% pure form of BT through a process that was “relatively environmentally benign” and which they estimated could be improved to yield the chemical for less than $19 a pound.
However, researchers at Michigan State University demonstrated that genetically engineered E.coli bacteria, combined with fiber from corn hulls, could produce BT in a more environmentally friendly manner. They estimated that the cost of producing BT could be reduced to less than $19 per pound.
The Chemical Biological Center, which is receiving approximately $24 million in funding over the next five years for expansion and upgrades, is working to scale up the BT production process using biomanufacturing techniques. Overall, the collaboration between military researchers and biotechnology solutions offers a promising alternative to conventional manufacturing methods. By harnessing the power of microbes, the military can produce biofuels and specialty chemicals in a more sustainable and cost-effective manner, ensuring a reliable supply chain and reducing dependence on limited resources.
NAWCWD, Amyris collaborate to develop, test high-energy biosynthetic fuel
In May 2020, the Naval Air Warfare Center Weapons Division (NAWCWD) and biotechnology company Amyris collaborated to develop and test a high-energy biosynthetic fuel. The project, funded by the Defense Advanced Research Projects Agency’s Living Foundries: 1000 Molecules Program, aimed to create a high-density missile fuel using specially developed yeast cells.
The goal of the project was to create biosynthetic surrogates for synthetic missile fuels, which are expensive. Biosynthetic fuels have the potential to reduce costs, increase the range and fuel economy of aircraft, ground vehicles, and ships, and reduce emissions of toxic particulates and greenhouse gases.
The process developed by NAWCWD’s team involved converting a complex mixture of biosynthetic hydrocarbons, specially developed yeast cells, into a high-density missile fuel. The fuel was ground-tested in a liquid fuel ramjet test stand, marking a significant achievement.
The biosynthetic fuel, named BioRenewable-1 (BR-1), exhibited up to 19% higher volumetric energy density compared to conventional jet fuel. This energy density was comparable to JP-10, a synthetic fuel currently used to power cruise missiles globally. The successful testing of BR-1 in both a turbine engine and a system simulating conditions found in a liquid fuel ramjet engine demonstrated its potential for high-performance military applications.
Dr. Anne Cheever, program manager for DARPA’s Living Foundries program, highlighted the advantages of biologically produced fuels in terms of cost and performance. They could serve as additional sources of military-grade fuels during periods of higher demand.
Logistics costs are a crucial consideration for any fuel source. The transportation of large quantities of fuel can be expensive and vulnerable in the supply chain. The use of yeast and sugar as fuel precursors was suggested as a more cost-effective and potentially less vulnerable alternative due to their lower value and ease of acquisition.
The collaboration between NAWCWD and Amyris in developing a high-energy biosynthetic fuel represents an important step forward in sustainable fuel solutions for military applications. By harnessing the power of synthetic biology, the project aims to create more efficient, cost-effective, and environmentally friendly alternatives to conventional fuels, contributing to a greener and more sustainable future.
Here are some of the latest breakthroughs in biofuels for jet and diesel engines:
- In 2022, the U.S. Department of Energy announced that it had awarded $100 million in funding to 11 projects to develop new biofuels for aviation. The projects will focus on developing biofuels from a variety of sources, including algae, waste grease, and agricultural residues.
- In 2023, the European Union announced that it would require all jet fuel to be blended with at least 5% biofuel by 2030. This is a major step towards reducing the environmental impact of aviation.
- In 2023, a consortium of companies, including Boeing, Airbus, and Shell, announced that they had successfully tested a jet engine that was powered by 100% biofuel. This is a major milestone in the development of biofuels for aviation.
- In 2023, Researchers from Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley have made a significant breakthrough in biomanufacturing by engineering bacteria to produce carbon products that could lead to sustainable biochemicals. The team combined natural enzymatic reactions with a new-to-nature reaction called the “carbene transfer reaction,” offering an alternative to chemical manufacturing processes dependent on fossil fuels. By using an engineered strain of the bacteria Streptomyces, the researchers replaced expensive chemical reactants with natural products that can be produced by the bacteria when fed sugar. The result is a more environmentally friendly and scalable process for synthesizing carbene chemistry, which has applications in fuel and chemical manufacturing, as well as drug discovery and synthesis. The study opens up possibilities for reducing industrial emissions and advancing greener, sustainable biomanufacturing solutions.
Biofuels produced through synthetic biology offer several advantages over traditional fossil fuels. They are renewable, sourced from biomass or waste materials, reducing reliance on finite fossil fuel reserves. Additionally, biofuels have lower carbon emissions, contributing to the reduction of greenhouse gas emissions and the mitigation of climate change. Their compatibility with existing infrastructure and engines makes their adoption and integration into the transportation sector more feasible.
Despite the progress made in biofuel production through synthetic biology, there are challenges that need to be overcome. Researchers are actively working on improving production efficiency, scalability, and cost-effectiveness. This includes developing robust biofuel production platforms, optimizing microbial strains, and exploring novel feedstocks. Advances in synthetic biology tools, such as high-throughput screening and computational modeling, will further accelerate the development and implementation of biofuels.
In conclusion, synthetic biology is driving the advancement of biofuels for jet and diesel engines, offering sustainable and environmentally friendly alternatives to traditional fossil fuels. Through the engineering of microorganisms, scientists are optimizing fuel production pathways, enhancing the efficiency and yield of biofuels. These developments have the potential to significantly reduce carbon emissions and contribute to a greener future in the aviation and transportation sectors.
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