Cracking a tough nut

His work turns waste from rubber plantations into diesel fuel and may help smallholders in Indonesia. ‘That is what I like about Chemical Technology: you produce useful products!’ Yusuf Abduh defended his PhD in Chemical Technology on 27 February.

He has only returned to Holland to defend his thesis. For two months now, Yusuf Abduh has been working as a lecturer at the Institut Teknologi Bandung, a university with a long history of partnership with the University of Groningen. Before moving back to Bandung, Abduh did his PhD research at the Department of Chemical Engineering in Groningen.

‘I took my Master’s degree here as well, in Professor Erik Heeres’ lab’, Abduh explains. ‘And he offered me this project.’ His job was to see if he could find a cost-effective way to extract oil from the seeds of the rubber tree and convert it into biobased products. Although some seeds are used for the propagation of rubber trees, most of them are simply left to rot on the plantations.

Abduh managed to find the optimal way to extract oil (you can read about it in the press release ) and turn it into diesel fuel. ‘The most challenging part of my project was that I had to crack the nuts before I could start the extraction’, Abduh says smiling. If he used a piece of stone as a hammer, he could crack some six nuts a minute. ‘But not all of them were good. Some had been affected by fungi and couldn’t be used.’

He did his research in Groningen in the lab, but as the aim of his work was to see if harvesting the nuts was commercially interesting for smallholders in Indonesia, he and a team from Groningen also tested his lab techniques in the field.

‘As might be expected, the oil yields were lower in the field experiment’, he explains. ‘One factor is that we had to store the seeds for around eight months before the experiment.’ And storage conditions can affect the quality of the oil. Higher water content makes a more acidic oil, which gives a lower yield of diesel.

The seeds must be dried to about seven percent moisture content and then stored in a proper environment. Although this is not a great technical challenge, there are few facilities in the remote areas where the smallholders have their plantations. Abduh: ‘However, the people there are very resourceful. They only need practical instructions and will then build the necessary equipment themselves.’ It would be too complicated to tell the farmers to dry the seeds to seven percent moisture. ‘But if we could tell them how long they need to dry the seeds and at what temperature that would work.’

Now that he’s back in Indonesia, Abduh would like to see the potential of rubber seed oil realized. This April, a delegation from the University of Groningen will perform more field tests on Sumatera, to demonstrate the process. Abduh will be involved in these tests, which are hosted by the Institut Teknologi DEL.

‘We know the process works on a small scale’, he says. In his thesis, Abduh calculated that the production of oil from rubber seeds could be cost effective in remote areas. This would allow the smallholders to produce oil that could be used in generators or made into diesel fuel. ‘In these remote areas, the fuel prices are much higher than elsewhere in Indonesia’, Abduh explains. The rubber oil might also be interesting for large-scale oil production.

‘Whether this is viable depends on several factors’, he says. One factor is the quantity of seeds that a hectare of rubber trees can produce. Estimates vary wildly, from between 100 to 2000 kilos per hectare per year. Furthermore, a method must be devised to collect the seeds. ‘At the start of my project, we envisioned netting underneath the trees that would catch them, but we haven’t really developed this idea.’ If large-scale production of rubber oil proves viable, that would be good news. ‘The product has no real downside. To produce palm oil, you need dedicated plantations. The rubber trees are already there!’

His interest in Chemical Technology, being able to make useful products, is as keen as ever. He is now trying to get funding to start research at Bandung. ‘Doing a PhD was an important step’, he says. ‘You don’t just learn experimental skills but also soft skills, like how to develop as a scientist and how to think scientifically.’

Check out the Yusuf Abduh webpage at ITB.