When it comes to alternative fuels, currently ethanol is king. Almost all ethanol produced in the United States is fermented from readily available sugars in corn. Ethanol from corn has also come under much criticism lately, accused of being responsible for rising food prices.
Researchers are looking at alternate biomasses as food for microorganisms to ferment into ethanol. The most attractive are known as lignocellulosic biomass and include wood residues (including sawmill and paper mill discards), municipal paper waste, agricultural residues (including sugarcane bagasse) and dedicated energy crops (like switchgrass). The problem is, unlike corn, the sugars necessary for fermentation are trapped inside the lignocellulose.
Govind Nadathur and his colleagues at the University of Puerto Rico have been looking at unusual ecosystems and unusual organisms to find enzymes to help extract these sugars.
"Wood falls into the ocean. It disappears. What's eating this biomass? We found mollusks that eat the wood, with the help of bacteria in their stomachs that produce enzymes that break down the cellulose. We found something similar in termites," says Nadathur. They plan on using these enzymes as a key step in a closed, integrated system that would not only produce ethanol, but would also produce sugar, molasses, hibiscus flowers and biodiesel with a minimum of waste.
It all starts with sugar cane and hibiscus flowers, grown on local lands. These produce not only the obvious products such as refined sugar, molasses (which is used to make rum) and flowers, but also a large amount of waste in the form of biomass. Using the enzymes in their library, Nadathur and his colleagues could break down the biomass to sugars and ferment them to ethanol, trapping the carbon dioxide that is produced during fermentation. They then would feed the carbon dioxide to microalgae in ponds that would produce a polymer that could be refined into biodiesel or jet fuel. The spent microalgae could then be harvested and used as fertilizer for the next round of sugar cane and hibiscus, thereby closing the cycle.
"There used to be a booming sugarcane industry in Puerto Rico, but in the mid-1990s it died. It could not survive economically. By creating a closed-loop system that utilizes the waste to create additional products and feeds back upon itself, suddenly growing sugar cane becomes economically feasible again," says Nadathur.
They are currently working with a company called Sustainable Agrobiotech of Puerto Rico to build a pilot program which they hope to have running by early 2009. Should the pilot program prove successful, there is plenty of adjacent farmland to upscale.
Another promising biofuel is hydrogen. Already many car manufacturers are producing hydrogen concept cars and pilot programs using hydrogen-powered buses already are gaining acceptance in Los Angeles, with Burbank announcing the addition of a hydrogen-powered bus to its fleet in the summer of 2008. As more buses come online, there will be a greater need for hydrogen. Unfortunately, current chemical manufacturing processes for hydrogen are not that efficient or use fossil fuels as a source.
Sergei Markov of Austin Peay State University has developed a prototype bioreactor that uses the purple bacterium Rubrivivax gelatinosus to produce enough hydrogen to power a small motor.
"Certain purple bacteria, which usually grow in the mud of various ponds and lakes, have the ability to convert water and carbon monoxide into hydrogen gas (note: only a certain set could use CO). The problem was how to effectively supply each bacterial cell in a liquid bacterial soup with gaseous carbon monoxide," says Markov.
The answer was attaching the bacteria to numerous tiny hollow fibers inside an artificial kidney cartridge. Water and gasses can freely diffuse through the fibers, but bacteria, due to their large size, cannot. The hydrogen gas from a small fifty milliliter "artificial kidney bioreactor" has been directly injected into fuel cells and has produced enough electricity to power small motors and lamps. The only drawback is that carbon monoxide is not readily available , but Markov says it can be easily produced from biomass using a specific thermochemical process. There are also other bacteria that produce carbon monoxide.
One researcher and her lab, though, are investigating what could perhaps be considered the holy grail of hydrogen production: pure hydrogen from only water and sunlight, with a little bacterial help. Pin Ching Maness of the National Renewable Energy Lab in Golden, Colorado, is researching cyanobacteria that harness the power of the sun to break the bonds in water, separating the hydrogen from the oxygen. There is a problem. One of the hydrogenase enzymes the cyanobacteria uses in this process is sensitive to O2, which makes sustained hydrogen production extremely difficult.
Luckily a certain purple bacterium use a similar hydrogenase, but one that is tolerant to O2. Maness and her colleagues have identified the genes that the purple bacterium uses to produce the tolerant hydrogenase. They have also identified the genes a particular model cyanobacterium uses to produce the sensitive hydrogenase and have knocked it out. They are currently in the process of cloning the genes for the tolerant enzyme into the model cyanobacterium. The next step is to verify that the genes have been successfully incorporated into the genome and are expressed. Over the next few years additional research will need to be done to ensure all the requirements are there for the construction of an active hydrogenase enzyme.
Jim Sliwa | EurekAlert!
Hopkins researchers ID neurotransmitter that helps cancers progress
26.04.2019 | Johns Hopkins Medicine
Trigger region found for absence epileptic seizures
25.04.2019 | RIKEN
For the first time, physicists at the University of Basel have succeeded in measuring the magnetic properties of atomically thin van der Waals materials on the nanoscale. They used diamond quantum sensors to determine the strength of the magnetization of individual atomic layers of the material chromium triiodide. In addition, they found a long-sought explanation for the unusual magnetic properties of the material. The journal Science has published the findings.
The use of atomically thin, two-dimensional van der Waals materials promises innovations in numerous fields in science and technology. Scientists around the...
Flexible, organic and printed electronics conquer everyday life. The forecasts for growth promise increasing markets and opportunities for the industry. In Europe, top institutions and companies are engaged in research and further development of these technologies for tomorrow's markets and applications. However, access by SMEs is difficult. The European project SmartEEs - Smart Emerging Electronics Servicing works on the establishment of a European innovation network, which supports both the access to competences as well as the support of the enterprises with the assumption of innovations and the progress up to the commercialization.
It surrounds us and almost unconsciously accompanies us through everyday life - printed electronics. It starts with smart labels or RFID tags in clothing, we...
The human eye is particularly sensitive to green, but less sensitive to blue and red. Chemists led by Hubert Huppertz at the University of Innsbruck have now developed a new red phosphor whose light is well perceived by the eye. This increases the light yield of white LEDs by around one sixth, which can significantly improve the energy efficiency of lighting systems.
Light emitting diodes or LEDs are only able to produce light of a certain colour. However, white light can be created using different colour mixing processes.
Researchers led by Francesca Ferlaino from the University of Innsbruck and the Austrian Academy of Sciences report in Physical Review X on the observation of supersolid behavior in dipolar quantum gases of erbium and dysprosium. In the dysprosium gas these properties are unprecedentedly long-lived. This sets the stage for future investigations into the nature of this exotic phase of matter.
Supersolidity is a paradoxical state where the matter is both crystallized and superfluid. Predicted 50 years ago, such a counter-intuitive phase, featuring...
A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter
17.04.2019 | Event News
15.04.2019 | Event News
09.04.2019 | Event News
26.04.2019 | Life Sciences
26.04.2019 | Physics and Astronomy
26.04.2019 | Physics and Astronomy