More efficient production of bioethanol and biogas

Non-food crops such as miscanthus and maize can as biofuels replace fossil fuels. But this requires expensive chemical or physical pretreatment of the crops. Scientists of Plant Research International are working on the breeding of plants that no longer need such pretreatment.

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Crops such as sugar cane, wheat or oilseed rape are often used for the production of bioethanol or biogas. Problem is that the biofuel from these crops is competing with food production. This can be overcome by producing biofuel from non-food crops such as miscanthus or the total maize plant.

Miscanthus and maize are extremely suitable for the production of bioenergy because they produce large amounts of biomass. The way in which the sugars are locked in the cell wall is less ideal. The sugars from the cell wall – consisting of cellulose, hemicellulose and pectin – must be freely available for the production of biofuel. Fungi can then, via fermentation, convert these sugars into bioethanol or biogas. The sugars, however, are so strongly locked in the cell wall that physical and chemical pre-treatment is necessary. These are costly treatments and chemical pre-treatment also has negative effects on the environment because harmful chemical waste products are remaining.

Changing the cell wall composition

Our scientists are attempting to change the composition of the cell wall in such a way that chemical pre-treatment is less aggressive and less expensive, or even unnecessary. The sugars are normally well protected by lignin. This substance forms a strong bond with cellulose and hemicellulose, which gives the plant its sturdiness. The bond also prevents pathogens entering through the cell wall. The scientists are identifying the genes that are involved in the bond between lignin and (hemi)cellulose and are switching off the genes. This is how they attempt to develop plants with smaller amounts of lignin or with a less strong bond between lignin and sugars.

A breeding programme is very costly and it may take ten years before new varieties are reaching the market. Our scientists are therefore closely cooperating with breeding companies who are using the information of our scientists for crossing in the right properties via classical breeding. The scientists are also cooperating with bioethanol-producing companies. This gives them feedback about the positive - or negative – properties of the new crops. This system has already yielded some miscanthus lines that are more suitable for bioethanol production.

The researchers also wish to utilise the released cellulose for other applications than bioethanol, such as cellulose-based bioplastic. This plastic is more elastic than cellophane, which is produced from mineral oil.