PhD at Risø DTU: Biochar

	Facts Name: Esben Wilson Bruun Education: Biologist from the University of Copenhagen, 2003 Project title: Effect of biochar on soil nutrient dynamics, GHG emissions and plant growth Supervisors: Henrik Haugaard-Nielsen og Per Ambus Employment at Risø: March 2008 – February 2011 Read more about biochar

From waste water to biochar
Having worked as an information officer for some years at the waste water centre in Avedøre’ – a large sewage treatment plant south of Copenhagen – I wanted to work in depth again and return to science. So in the spring of 2008 I started as a PhD in the programme eNeRGy (NRG) in the Biosystems Division.
In my previous job I had the daily responsibility for a visitors centre with 5000 annual visitors, from state school pupils to university students, and a working day consisting of communication and running the centre.

’Spoilt’ PhD students
I have been realising that the PhD study is much more than coffee cups and articles: At Risø I collaborate with people of widely different professional backgrounds and nationalities. I have had to communicate my knowledge in a scientific form as well as in a popular form (like now) at seminars, courses, conferences and when teaching at DTU.

It was easy to fit in because of the good social atmosphere with nice dedicated colleagues who are able to talk about other issues than only research/work. During lunch and coffee break we are discussing energy, politics, environment or entirely different things - I think it is exciting to be a part of this environment.
There are not as many students at Risø as at more traditional educational institutions. As a new student, this is both good and bad. Bad, because it would be nice with a little more fun sometimes, but also good, because a student becomes a little more 'spoilt'.

There is more time for supervision, more access to equipment and technical assistance, and I feel I am looked upon as an 'accepted' colleague rather than just a student, as it might be the case in places with many PhD students.

BIOCHAR and bio-oil from straw
My project is part of a major collaborative project between my programme NRG in the Biosystems Division and DTU Chemical Engineering. In brief the project is about producing bio-oil from straw and at the same time utilising the coke residual product, - biochar.

In the process taking place in a 'pyrolysis reactor' comminuted straw is heated to about 500 degrees without oxygen (pyrolysis process) and bio-oil is formed, together with pyrolysis gas and biochar. The bio-oil can be used at power plants for instance, the pyrolysis gas can be used internally to run the process and biochar can be used as a fertilizer, and simultaneously mitigate climate change through carbon storage.

My research assignment is to examine the degradability of biochar in soil and its impact on a number of microbial soil processes , including greenhouse gas emissions. Biochar is very slowly degradable.

So by converting straw to slowly degradable biochar the carbon is captured that was originally built into the wheat via photosynthesis and it is stored for centuries in the soil. That is why the biochar-'technology' is called' carbon negative ', because carbon actually is removed from the atmosphere. Carbon neutral 'technologies are for example wind and solar energy. Carbon storage through biochar is one of the methods to be discussed at the climate summit in Copenhagen in December.

Biochar used for soil improvement
Apart from carbon storage, several studies have demonstrated that biochar has soil improvement properties. The large surface area makes biochar capable of preserving nutrients in the soil. Experiments have shown that the amount of added nutrients (fertilisers) can be reduced in sandy soils containing biochar
Since the research field 'biochar' is a relatively new area, there are still many questions to be answered.



Esben Bruun