News and Trends

Scientists from the Sandia National Laboratories are studying if one of California's most polluted lakes can be turned into a source of algae biofuel. They are hoping that the Salton Sea Biomass Remediation (SABRE) project will help determine whether algae biofuels can help solve the US energy needs.

Salton Sea in Southern California currently has elevated levels of nitrogen and phosphorus due to agricultural runoff. Algae thrive in these conditions, causing a lot of environmental problems. Researchers from Sandia are now looking to use this algae as a biofuel source as well as to clean the lake.

The first phase of the project saw Sandia scientists test a new method for producing algae, called an ĎAlga Turf Scrubber' floway system. The system pulses water from the lake in waves across a sloped floway. The algae consume the nutrients, and clean water is released out the other side. Solar powered pumps power the system, while periodic farming of the algae can be done using farming equipment. By producing algae native to the area, the new system is more resistant to pathogens and predators.

In 2006, Idaho was devastated by the pale cyst nematode, a rare potato pest. While the pest problem was solved, bromide, a component of a highly toxic pesticide sprayed on farmlands, remains on the soil and some of the crops grown in it, including alfalfa grown for cattle feed. The extent of contamination was not realized until pesticide treatments stopped in 2014 after a farmer noticed side effects in cattle fed with crops grown in the treated soil.

Employees at Idaho National Laboratories Biomass Feedstock National User Facility have studied how farmers can benefit from contaminated alfalfa as a combustible fuel. The team transformed bales of alfalfa into pellets or cubes that can be used as fuel in coal-fueled plants. The INL team then monitored the air to determine if bromide was released at any point when alfalfa is processed into fuel.

Researchers found bromide was only released during an emergency procedure in the pellet-forming process. Burning the produced fuel also yielded no bromide to the air. It stayed in the ash, which can then be used to produce cement.

Although alfalfa can burn as a fuel, there's still work to be done as alfalfa fuel tends to "foul" burning chambers, leaving a material not unlike creosote caked in a home chimney.

Research and Development

Michigan State University researchers are experimenting with harvesting seed oil to make biofuels that could power jets and cars. Researchers show that the chloroplast, where plant photosynthesis occurs, participates in providing seed oil precursors.

Scientists have identified a new enzyme, PLIP1, or Plastid Lipade 1, that interacts with lipids inside the chloroplast. The enzyme was found to break down lipids that make up the chloroplast thylakoids. Leftover lipid products are then transported to the endoplasmic reticulum, a massive cellular factory, where they become building blocks for seed oil.

The team wants to increase the level of PLIP1 in biofuel-targeted plants to produce more seed oil. However, initial testing has unexpectedly led to a smaller plant with more oil per seed but fewer seeds, and higher defense activity. With oil production and plant defense functions appearing to not coexist well, the team are thinking of new ideas to bypass this limitation.

Trichoderma reesei is widely used cellulase production. However, its xylanase activity must be improved to enhance its ability to degrade lignocellulose. While several transcription factors play important roles in this process, Rui Liu from the Chinese Academy of Science want to focus on specific xylanase transcription factors that would regulate xylanase activity.

The team studied a novel zinc binuclear cluster transcription factor, designated as SxlR (specialized xylanase regulator). They found that it represses xylanase activity, but not cellulase activity. Further investigations revealed SxlR could bind to the promoters of xylanase genes (xyn1, xyn2, and xyn5) and directly regulate transcription and expression. Deletion of SxlR in T. reesei RUT-C30 generated the mutant ∆sxlr strain, which possesses higher xylanase activity as well as higher hydrolytic efficiency on pretreated rice straw.

This study revealed the transcriptional repressor of xylanase genes, Sx1R, which adds to the understanding of the regulatory system of cellulase and hemi-cellulase in T. reesei. The deletion of SxlR may also help improve the efficiency of T. reesei for lignocellulose degradation.

Energy Crops and Feedstocks for Biofuels Production

In Uganda, the chaff left from threshed panicles of millet and sorghum is a low value, lignocellulose-rich agricultural by-product. Currently, it is used as a medium for growing edible Oyster mushrooms (Pleurotus ostreatus). Peter Ryden of the Quadram Institute of Bioscience in the UK, assessed the potential of the residual post-harvest compost as feedstock for producing ethanol.

Sorghum and millet chaff derived from spent oyster mushroom composts were assessed at small-scale and low substrate concentrations for ethanol production. Millet-based compost had low cellulose content and did not liquefy effectively. The ethanol yield was 63.9 g/kg dry matter of original material.

On the other hand, compost from sorghum chaff had higher cellulose content and could be liquefied at high substrate concentration. This enabled yeasts to produce more ethanol at up to 186.9 g/kg dry matter of original material.

Spent mushroom compost derived from sorghum chaff has the potential to be an industrial substrate for producing bioethanol. However, compost from millet does not provide a high concentration of ethanol to make it industrially attractive.

California-based biorefining company Aemetis has started producing bioethanol from orchard waste. The company announced this after successfully completing the construction of an integrated demonstration unit. The company said it produced the material from technologies from itself, LanzaTech and InEnTec.

The demo plant, located at InEnTec's Technology Center in Richland, Washington, is processing various feedstocks such as waste orchard wood and nutshells from California's Central Valley into cellulosic ethanol. California has more than one million acres of almond, walnut, and pistachio trees that currently produce over 1.6 million tons of waste wood and shells per year.

Yields and other data from the operation of the demonstration unit will be provided to the US Department of Agriculture (USDA) as part of completing the Phase II loan guarantee process under the USDA 9003 Biorefinery Assistance Program.

Biofuels Processing

Stanford University scientists have recently discovered a new, more sustainable way to make ethanol without using crops. Their new technology consists of three basic components: water, carbon dioxide, and electricity delivered through a copper catalyst.

Principal investigator Thomas Jaramillo, an associate professor from Stanford and at the SLAC National Accelerator Laboratory said that copper is one of the few catalysts that can produce ethanol at room temperature. With just electricity, water and carbon dioxide, it can make ethanol. However, it also makes other compounds simultaneously, including methane and carbon monoxide. Separating these products would be expensive and require a lot of energy.

Scientists aimed to design copper catalysts that selectively convert carbon dioxide into higher-value chemicals and fuels, such as ethanol and propanol, with minimal byproducts. The team chose three samples of crystalline copper, namely copper (100), copper (111) and copper (751). The number describes the surface geometry of each copper crystal.

When the team applied a specific voltage, the electrodes made of copper (751) were far more selective to liquid products, such as ethanol and propanol, compared to the other two. The Stanford team would also like to develop a technology capable of selectively producing carbon-neutral fuels and chemicals at an industrial scale.

Oak Ridge National Laboratory, together with Wake Forest University and Georgia Institute of Technology, has developed a method to use carbon derived from waste tires to convert used cooking oil into usable biofuels.

Using a novel, reusable carbon material derived from old rubber tires, the research team developed a simple method to convert used cooking oil into biofuel. The team's method combines recovered carbon from tires with sulfuric or sulfonic acid, which are then mixed with free fatty acids in vegetable oils to produce biofuel.

Carbon powder from tires have been useful in developing lithium-ion, sodium-ion and potassium-ion batteries and supercapacitors. This new waste oil-to-biofuel conversion adds a new approach to waste tire recycling initiatives and opens a pathway for more inexpensive and high value-added waste tire-derived products.