In principle, it is possible to produce the same types of fuels and chemicals from wood, grass and straw as those made from petroleum. This can be done with the aid of biorefineries that convert the green raw materials into valuable products. ECN is looking for ways to extract as much raw material and therefore money as possible from each tonne of biomass, in an environmentally friendly manner of course. Herman den Uil from ECN Biomass, Coal and Environmental Research: “Pyrolysis is one of the important technologies to this end.”
“The idea is that you do not only convert biomass into fuels, but also into chemicals at the same time because these yield more per kilogram. This will allow the use of biomass to be profitable sooner,” says Herman den Uil, who leads ECN’s research activities into transport fuels and chemicals. It is important for the chemical industry to be able to use green raw materials in a cost-effective manner. This can help the sector reduce its dependence on fossil raw materials and significantly cut CO2 emissions. This is important given that the chemical industry does not only use natural gas and oil-derived products for its energy supply (40%), but primarily also as a raw material for products (60%).
Ensuring suitability of biomass as raw material for chemical industry
Den Uil provides an example. “Wood, for example, is made up of cellulose (50%), hemicellulose (25%) and lignin (25%). One tonne yields approximately 250kg of ethanol. At €400 per tonne, this yields €100. If you manage to obtain even 80kg of chemicals from lignin, such as phenols that can yield approximately €1 euro per kg, the total return is €180, or 80% higher. In that case, the conversion is therefore considerably more cost-effective,” says Den Uil.
The second most common biopolymer on earth
ECN researcher Paul de Wild, who is studying the conversion of biomass together with Den Uil: “Cellulose and hemicellulose are converted into sugars with the help of enzymes, which are in turn allowed to ferment into ethanol, or alcohol. Lignin is far more difficult to convert into valuable chemicals. That is why it is often said that you can make everything from it, except money.
For the ECN researchers, however, this is no reason to ignore lignin. “Lignin consists of a cross-linked network of phenol-like ring compounds and is the most common biopolymer on earth after cellulose. It gives tree trunks their sturdiness and is not so easily disrupted or broken. That’s logical, given that tree trunks must be able to withstand moisture, insects, fungi and bacteria in order to last for many years,” indicates De Wild. He and Den Uil nevertheless believe that money can be made out of lignin.
Looking for an economical process
Den Uil: “We do not believe that combustion is the only option. Our aim is to obtain useful substances from lignins and demonstrate in turn that you can indeed make money out of them. If this works, we can extract even more value out of biomass and help accelerate the use thereof. Other teams around the world have already proven that lignin can be converted into various substances. We are looking primarily for an economic process that enables you to make products from lignin that can compete with those made from fossil raw materials. ECN is staking its money on pyrolysis, i.e. the heating of biomass without free oxygen in an atmosphere of pure nitrogen or steam.”
“Lignin pyrolysis must be done in an intelligent way, otherwise you will obtain a type of molten plastic before you know it, which sticks everywhere and blocks everything,” continues De Wild. He would like to reveal more about the new process for producing so-called pyrolytic lignin oil from lignin, but ECN is currently busy drawing up a patent application for this invention.
Vanillin from biomass
Lignin pyrolysis also produces a mixture of phenolic compounds. “This allows you to fully replace the phenols in resins that originate from fossil raw materials,” says De Wild. “Lignin oil also contains aromatic substances and flavours, which can yield between €5 and
€10 per kg. These are the same substances that escape from charcoal during a barbecue and give meat and fish such a unique flavour. Another example is the phenolic compound vanillin, which manufacturers use to give their products a vanilla flavour. Phenols are also responsible for the flavour of nutmeg, and so on.”
Theoretically, the aromatic compounds from lignin can also be a raw material for plastics such as polyesters, but Den Uil does not expect this to be an option in the short term. “You need extremely pure compounds to produce plastics. We want to start by making simple products that yield money. Afterwards, we will take another step further.”
Other research
ECN has test installations for converting biomass into various fractions, including sugars and lignin. ECN is also developing technology for converting these fractions into transport fuels and chemicals. R&D is carried out in close cooperation with industry through national and international research projects.
Contact
ECN Biomass, Coal and Environmental Research
Tel.: 022 456 4106
E-mail Herman den Uil
Info
Browse to chemicals from biomass if you want to find out more about this topic.
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