Scientists develop low-lignin eucalyptus trees that store more CO2, provide more cellulose for biofuels

A team of Taiwanese and U.S. scientists has succeeded in developing eucalyptus trees capable of ingesting up to three times more carbon dioxide than normal strains, indicating a new path to reducing greenhouse gases and global warming. The new trees also have properties that make them more suitable for the production of cellulosic ethanol. In this sense, they can be seen as part of third-generation biofuels. This generation is based on crops modified in such a way that they allow the application of a particular bioconversion technology (previous post). Analyses show that there is a very large potential for the production of sustainable biomass from Eucalyptus in Central Africa and South America.

Under the auspices of Taiwan's National Science Council, staff members at the Taiwan Forestry Research Institute (TFRI) under the cabinet-level Council of Agriculture and North Carolina State University in the United States carried out the gene modification project that not only creates eucalyptus with a higher than normal CO2 absorptive capacity, but also causes them to produce less lignin and more cellulose.

TFRI researcher Chen Zenn-zong explained that cellulose, hemicelluloses, and lignin in trees are all created from carbon elements. However, only cellulose can be used in commercial processes of pulp manufacturing and bio-ethanol extraction. Lignin is the 'glue' that holds cellulose together. Breaking down the lignin barrier is a major obstacle for the production of cellulosic ethanol.

The idea behind the whole project is to increase the value of genetically-modified eucalyptus to related industries, so we adjusted the ratio of cellulose and lignin. Meanwhile, we enhance the tree's capacity in absorbing CO2 to reduce greenhouse gases, so that more trees planted for production, the more CO2 are consumed. - Chen Zenn-zong, Taiwan Forestry Research Institute

With every eucalyptus carrying 18 percent less lignin and 4.5 percent more cellulose, Chen estimated that a pulp factory with an annual output of 1 million tons could generate extra revenues of NT$1. 2 billion (about US$36 million) every year.

Eucalyptus is a fast-growing tropical tree species used as a biomass source for bioenergy, and for pulp and paper manufacturing. Major research efforts are under way to map the tree's genome with the aim to improve it as an energy crop. Eucalyptus is on the agenda of the U.S. Department of Energy's Joint Genome Institute (DOE JGI), with an international team working on increasing biomass production and the carbon sequestration capacities of the species (more here):
energy :: sustainability :: bioenergy :: biofuels :: ethanol :: cellulose :: carbon sink :: biomass :: biomass-to-liquids :: pyrolysis :: co-firing :: energy crops :: eucalyptus ::

So far, researchers have succeeded in developing high yield varieties. But this is the first time that the eucalyptus tree has been modified in a way that allows it both to store more carbon while at the same time yielding less lignin.

Earlier, geneticists and plant biologists succeeded in creating low-lignin poplar and willow (more here), as well as sorghum (earlier post) with the specific aim of improving pulping and ethanol production respectively.

With an emerging global carbon and biomass market, it becomes interesting to develop crops that sequester more CO2. They can be used as carbon sinks in afforestation and reforestation efforts and fetch carbon credits. Alternatively, with their high biomass yields, they will be used more and more for the production of next-generation biofuels. These include cellulosic ethanol, and fuels obtained from pyrolysis (bio-oil) and from biomass-to-liquids processes resulting in synthetic biofuels (gasification and synthesis by the Fischer-Tropsch process).

Eucalyptus is an interesting crop for the production of solid biofuels as well (woody biomass), that can be co-fired with coal or used in dedicated biomass power plants. Estimates show that there is enormous potential for the establishment of eucalyptus plantations in the tropics. A European project analysing the production of 'green steel' based on utilizing biomass from the tropics indicated that some 46 million hectares of land are available in Central Africa alone. In Brazil, another 46 million hectares are suitable. The land in question can sustain eucalyptus plantations without any major negative environmental footprint (previous post).

References:
China Post: Gene-modified eucalyptus ingests more CO2 - September 14, 2007.

Biopact: Scientists release new low-lignin sorghums: ideal for biofuel and feed - September 10, 2007

Biopact: Joint Genome Institute announces 2008 genome sequencing targets with focus on bioenergy and carbon cycle - June 12, 2007

Biopact: Virginia Tech researchers receive $1.2 million to study poplar tree as model biomass crop - June 26, 2007

Biopact: Celebrity spotting: Marc Van Montagu and GM energy crops - July 05, 2007

Biopact: Green steel made from tropical biomass - European project - February 08, 2007