Here’s a cool interview with the UK Institution of Mechanical Engineers on the process of converting landfill waste into usable jet fuel I caught on BBC radio.
What is this process? Why do we want to do this?
Processing landfill waste into green fuel. The resulting fuel is a good quality one and is better than conventional jet fuel. This green fuel can be easily blended into existing fuel so it is straightforward in the pov of the engines. This will help in a reduction in landfill and greenhouse gas emissions.
The raw materials coming in is not controlled. One day there could be a lot and the next you might not get the equal amount. The inputs are variable and stuff in there may be contaminated.
What is the process?
The main process is called the Fischer-Tropsch.
First – High Plasma Gasification. Breaking down rubbish into simple molecules.
Second – Clean the gas (one of the most important steps). Free the gas from harmful trace materials.
Third – Build up the small molecules to large again. Chemical synthesis to make it into well-defined product.
Is any type of waste usable?
Glass, sand, metals are removed. Only the organic part goes in. Plastics, paper, food waste are ok.
This is dependent on the taxation regime and the need for carbon taxes to subsidize what they do. There are huge taxation being put on landfill, emissions trading scheme, carbon target. And incentives to do things like not throwing away waste and filling landfills. But it depends on the taxation regime and the need to subsidize what they do.
The Fisher-Tropsch process, started in 1930s, was originally was intended to turn coal into liquids, then gas into liquids. Now waste is being made into liquids.
What’s the difference between waste and biomass?
Waste is in smaller quantities.
How much fuel can be produced?
A typical plant produces half million tonnes waste a year, which converts to 100,000 tonnes of fuel: half jet fuel, half diesel.
The Fisher-Tropsch process started in the 1930s but did not catch on. Is there any new tech now to make the process more efficient?
Most of the inefficiency comes at the beginning. About 2000 tonnes of waste is blasted through the plasma per day. A lot of energy is needed – approx. 12 megawatts of plasma needed to combust the waste initially. You put in 1/3 electricity that you get produced at the end.
Does it make economic sense?
There are internal processes that can recycle the energy that is created to power back into the gasification process. The idea is to squeeze the most valuable output out of the waste. There aren’t many alternative ways. In order to get a sustainable jet fuel, it has to be good quality. You need to accept certain energy loss on the way to achieve that goal.
Isn’t it just displacement of CO2? The energy you use has to come from somewhere else, what if it’s from a coal-burning electricity plant?
No, it is a sustainable process.
Is there any waste from the process?
There’s not a lot left. That’s a small percent of about 1-2% of the 2000 tonnes a day coming in. The key bit is, it’s a complex process. It produces 1% of British Airways demand for jet fuel. 99% are not using it. We need to do these to get it up 2-3%. 1% of one airline is not going to make a lot of difference.
Once the concept is proven it can be rolled out on a larger scale, a higher impact can be made. Cities produce rubbish and cities need airports — this is a natural connection. Hopefully more cities will adopt this process and make it more sustainable.