Gina Castell explains why.
‘What goes up, must come down.’ – Isaac Newton.
The famous quote resonates with the project ‘Real Time Control of Gasifiers’, albeit with a few tweaks. The idea behind the project is what goes in, must come out: by controlling what we put into the gasifier, we can control what gas comes out of it. The project is about finely tuning the bioenergy apparatus, so it will run better and give off better quality gas, reducing harmful emissions once and for all.
Why so controlling?
Not all biomass is exactly the same, like how no two humans are exactly the same. Different biomass have a different make-up, so they create different products (varying gas, tar, ext.). Biomass is also seasonal. In one season you find one biomass, and in another season you find another, just like seasonal fruit and veg. To deal with this, it’s necessary to control the gasifier so it works with all the different types of raw material, come summer or winter.
A year since starting up, the project has looked at the need for temperature control. When temperature is controlled inside the gasifer, we control the product gas it creates. The project also looks at how balancing the air to fuel ratio helps give off better gas.
However, control is influenced by results from experimentation. The project mainly experiments with Miscanthus, a plant biomass, in the UK. There is also experimentation with control techniques, as we need something to measure, and the idea is to develop cheap ways to monitor tar. Two techniques being used are flame analysis and fluorescence. In flame analysis, if we put oil on a flame, it changes from blue to yellow. So we can see how much tar is in the gas simply by looking at the colour of the flame. However, fluorescence is not so easy. The gasifier is loaded with all sorts of things, all emitting different wavelengths. As a result, the researchers need to be selective with the wavelengths they decide to detect for tar.
Tar creates a sticky situation, clogging up pipes in the apparatus. The danger is that when this ‘unclean’ gas is used in gas turbines, the tar will get stuck to the turbine blades, reducing the effectiveness of aero-energy. To remove this danger, we simply optimise the temperature so less tar is produced.
In short, the goal is to reduce harmful emissions. A controlled system, one that is finely tuned to work with all sorts of biomass, will giveway to a new and improved gas. If we can get better quality gas, we can reduce emissions. Simple.
So we’re one step closer to a cleaner atmosphere.
Time to take control and embrace the wonder gas!
Words by Gina Castellheim