Researchers at Swansea University have developed a process for creating hydrogen from plastic waste and are hopeful that it could one day be used to fuel cars. The process works by adding a light absorbing material to the waste plastic, placing it is an alkaline solution and leaving it exposed to sunlight. According to Dr Moritz Kuehnel from the chemistry department of Swansea University, any type of plastic can be used and the process could be cheaper than plastic waste recycling because the plastic does not need to be cleaned before being used.
Plastic waste recycling is suitable for dealing with polyethene terephthalate or PET, which is what the majority of plastic bottles are made from. However, many bottles that could be recycled still end up in a landfill or being burnt, simply because this is viewed as the easier option for some consumers. Currently, only a fraction of the billions of tonnes of plastic used every year is recycled.
The new process has the advantage that the waste plastic does not need to be cleaned prior to use. If there is a little grease or food waste present, this will not adversely affect it. The plastic is first cut and the surface is made rough by rubbing. A light absorbing material is then added to the plastic. This photocatalyst uses the energy from sunlight to transform it into chemical energy. The plastic is put into an alkaline solution and is left exposed to sunlight so that it produces hydrogen. Alternatively, a solar simulator lamp that mimics sunlight can be used.
The major advantage of the new process is that all sorts of waste plastic can be used and particles of grease or food can actually improve the reaction, rather than stopping it. The hydrogen that is produced can be seen coming off the surface of the solution in bubbles, and it is this that could potentially be used to fuel hydrogen cars in the future. The research is being funded by an Austrian petrochemical company and the Engineering and Physical Sciences Research Council and is being carried out with a Cambridge laboratory. It could take a number of years for the process to reach an industrial level and be rolled out.
In addition to producing hydrogen fuel from the waste, Dr Kuehnel said that the rest of the plastic could also be recycled into new plastic. In the case of PET, the ethylene glycol will produce hydrogen and CO2, but the remainder will stay in the solution and the chemical can be used in the production of new plastic bottles. Waste plastic PET is not currently often recycled into new bottles, because it needs to go through an expensive cleaning process and must be totally pure with no oil or grease present. The bottles produced could be cloudy and unattractive to consumers, unlike those made from virgin materials.
It is hoped that the new process can be rolled out on an industrial level in the future and that the hydrogen produced can be used as fuel for the hydrogen cars of the future.