A study conducted by a group of researchers at Uppsala University (Sweden) suggests that efficient production of hydrogen gas using the photosynthetic machinery of green algae is possible, contrary to previous skeptical views. Published in the journal PNAS, the study provides insights into the low efficiency problem and how it could be solved.

Hydrogen is one of the most promising renewable fuels which can be produced by splitting water molecule. The natural process of photosynthesis in green algae, which harnesses the energy of the sun to split water, is one biological way to produce hydrogen. The hydrogen ions generated from water splitting can later be formed into hydrogen gas through the work of a special class of enzymes called hydrogenases coupled to the photosynthetic electron transport machinery.

While it is known that green algae can produce hydrogen gas under certain conditions, previous studies have suggested poor commercial prospects due to very low efficiency. One skeptical view is that most of the hydrogen gas production in green algae is not directly powered by sunlight through photosynthesis but comes from other metabolic paths, making the green algae a poor hydrogen producer.

The focus of the Uppsala University study is the protein complex involved in light capture and photosynthetic electron transport, called Photosystem II or PSII. The researchers measured how the amount and activity of PSII varies in a wild type and a mutant strain of the green algae Chlamydomonas reinhardtii under different conditions, and thereby affects hydrogen production.

The researchers highlighted the finding that most of the electrons delivered to the hydrogenases (about 80 percent) originated from water splitting by PSII. This means that most of the hydrogen production is driven directly by solar energy, in contrast to popular views. This finding opens up a way to further improve hydrogen gas production in green algae through genetic engineering approaches that seek to preserve and enhance the function of PSII.

An Israeli delegation of elite biofuels researchers and innovators both from the academe and industry together with government program managers arrived in Washington (USA) to discuss with their American counterparts the opportunities for U.S.-Israel collaboration on research and innovation for production of advanced biofuels that can substitute for petroleum-based fuels.

Both countries share the goal of reducing dependence on fossil fuels. Israel launched an initiative in 2011 with an ambitious 10-year goal of reducing oil consumption by 60 percent by the year 2025. Israel has built a reputation in cutting-edge research and development particularly in the selection, bio-engineering and modification of fuel feedstock, growing novel feedstock on non-arable land and without using fresh water. This is also true with the more-efficient and cost effective production of fuels from feedstock using innovative chemical, physical and biological processes.

Sponsors of the meeting also stressed that finding alternatives to imported oil will be of benefit to the economic and security interests of the two nations especially at a time when high oil prices are dragging the economy and some oil-producing nations are using oil revenues to develop weapons that threaten their neighbors.

In Spain, researchers at the Canary Islands Technological Institute (ITC) are carrying out a project that seeks to optimize the process of converting banana waste into second generation biofuels.

The Canary Islands have huge banana surpluses that are not sold and these waste bananas end up in landfills. The availability of potential feedstock from waste banana stems and fruits gave reason for the ITC researchers to pursue the banana-to-biofuel project. Now they are studying how to optimize the production process particularly the proportion of raw materials introduced to capture the gas for eventual conversion into second generation biofuel. Although the project is still in the very early stage, the researchers look forward to helping reduce waste from the region's banana industry while providing renewable energy to the islands.

In the UK, a team of researchers at the University of Exeter have engineered the bacterium Escherichia coli to produce pure diesel fuel which is nearly identical to the conventional form used in current supplies.

With the knowledge that E. coli bacteria can turn the sugars supplied to them into fats to build their cell membranes, the researchers used advanced biotechnology to modify the bacterium so that it can use its oil to manufacture diesel. The new biodiesel is considered pure and apparently does not need to be blended with petroleum products as typically done in other biodiesels. Being compatible with current fuel infrastructure would make this new diesel attractive to oil companies.

The new biodiesel is currently produced in small quantities in the laboratory, but more work is expected to be conducted to prove the commercial viability of this technology.

This research was supported by a grant from Shell Research Ltd and a Biotechnology and Biological Sciences Research Council (BBSRC) Industry Interchange Partnership Grant.

Researchers at the National Renewable Energy Laboratory (US Department of Energy) and Weizmann Institute (Israel) have found a dramatic increase in the enzymatic breakdown of plant biomass with a combination of two microbial enzyme systems.

Enzymes produced by some microbes naturally degrade the cellulose in plant biomass, so that the sugars release from this breakdown can be fermented into ethanol. However, plants possess natural barriers that make it harder for the enzymes to target the cellulose in their cell walls, and overcoming this barrier increases the cost of producing biofuels. Researchers have been exploring various pre-treatment methods and combinations of enzymes that can hasten the breakdown of cellulose.

The present study, published in the journal Energy & Environmental Science, looked into the biomass-degrading mechanisms of two prominent enzyme systems. One is known as the free enzyme system, produced by a fungus, which is a cocktail of enzymes with one or several catalytic domains per enzyme. The other is termed cellulosomes, multi-enzyme complexes produced by a bacterium with multiple catalytic units per complex. When the two enzyme systems were combined, deconstruction of the cell walls occurred more efficiently.

Evidence from transmission electron microscopy revealed the different mechanisms of cellulose breakdown by both enzyme systems. Insight into these mechanisms may lead to new strategies for enzyme engineering for more optimal enzyme formulations in cellulosic biofuel production.

One big challenge in the commercial production of cellulosic biofuels, fuels derived from biomass such as grasses and wood, has been the cost of transporting raw biomass. A pilot plant will be built in Indiana (USA) by the Washington-based Mercurius Biofuels LLC with support from the Energy Department. The plant will use a novel approach to convert raw cellulosic biomass into an intermediate liquid chemical at smaller plants located near the feedstock source, making it more economical to ship to a large centralized facility where it will be converted to fuel.

Mercurius will use acids to break down cellulose and produce an intermediate chemical called chloromethylfurfural. Converting the cellulose to this chemical is more efficient than traditional fermentation process because it can capture all of the available carbon in the biomass. Fermentation releases one third of the carbon as carbon dioxide. Another key feature of the process is the fact that the acids used can be easily separated and then recycled. The chloromethylfurfural can be converted into diesel or jet fuel using industrial processes similar to petroleum refining processes, so it can be marketed easily.

Each part of the process has been demonstrated in small scale, including the final steps of producing diesel and jet fuel that meet specifications for use in vehicles.