Commercialisation of plastic waste derived fuel for generating electricity

Lead Research Organisation: University of the West of England
Department Name: Faculty of Environment and Technology

Abstract

Distributed power and security of electrical supply; with the advent of photovoltaic, wind, wave and other power generation technologies, there is a growing trend for the electrical energy generation to become more and more distributed. However, many of these power-generating systems, because of their reliance on natural effects, suffer from short-term peaks and troughs in their energy production. In many cases diesel engine generating sets provide a viable option to reduce the variability and augment the electrical generating capacity and dynamically optimise contribution from each source to the distributed electrical power generation.
The regulations defining incineration as a recovery process rather than a disposal activity are very demanding and generally require the incineration plant to have a high efficiency. The route of converting mixed plastic waste in to diesel fuel immediately removes the ambiguity of waste disposal versus waste recovery and as such would be highly desirable by local authorities and waste management companies.
Long-term maintenance of capital equipment depends, amongst other factors, on better sensors, data acquisition, data analysis and ultimately more capable predictive software models; in terms of sustainability 'engineering systems for life' is a strategic initiative that is gaining ground. The aim is to develop methodologies that can 'guarantee the required and predictable performance of complex engineering system throughout its expected operational life with optimum whole-life cost, taking in into account design, manufacture, maintenance, repair, overhaul and disposal or re-use'. A contribution to the development of this goal would be realised from the development of 'wear models' that allow predictive maintenance of diesel engine power plants. In the context of diesel engine power plants a key decision would be the choice between large slow speed longer lasting engines, which have good specific fuel consumption values but are expensive to acquire and install. The alternative is a high-speed multi-engine facility, which may be potentially cheaper to implement, but have shorter life and poorer SFC values. This work will contribute to this decision-making problem.
This research project will investigate Plaxx and a standard diesel fuel and compare them in terms of engine performance, engine emissions, wear and reliability. Trials on two single cylinder small engines have already demonstrated that Plaxx is a viable fuel for diesel engines. As part of this program Plaxx will also be used on a multi cylinder engine, a large fully instrumented single cylinder engine and finally on 1 MW generating set for extended runs and power supply to the grid. The two small single cylinder engine-generating sets will be equipped with variety of sensors to measure amongst other parameters, Plaxx and distillate diesel SFC, thermal and volumetric efficiencies and engine emissions. One of the single cylinder engines will have a modified liner incorporating a wear sensor to measure real time wear of liner. Lubricating oil samples will be monitored to measure metallic debris in real time and relate this to engine wear and performance. A series of designed experiments will be performed to relate the interaction of the various factors on performance, emissions and wear.
These trials will be performed for a range of fuel blends and load conditions. The aim is to develop predictive models and validate these models on the large single cylinder engine and in the longer term identify optimum running conditions for the 1MW engine. The investigation will develop a methodology to assist future planners with the type and mix of diesel engine power generating facilities in terms of engine size and fuel blends. Using Plaxx produced at the waste handling yards it will be possible to perform waste recovery by processing mixed plastic waste and provide electrical energy for the grid, sending less waste to landfill sites.

Planned Impact

The key beneficiaries other than academics will be:
-Recycling Technologies; A better understanding of Plaxx when used as a diesel fuel to generate power will immediately benefit Recycling Technology by enabling it to tailor the output from the pyrolysis process to meet the combustion and emission requirements when Plaxx is used as a substitute for Heavy Fuel Oil in diesel engines.The knowledge gained from this research, leading to a better understanding of Plaxx in terms of emission, performance and wear, will enable users of diesel engines to examine the suitability of Plaxx as a fuel with the likelihood of reduced costs.
-Waste handling organisations; Local authorities and waste management companies will have an opportunity to consider mixed plastic waste as a potential income generating commodity rather than waste that is costly to dispose off. This would be particularly beneficial in waste management and create an income stream and reduce the burden on local authorities and ultimately local council taxes.
-Worldwide; In the broader context, establishing the efficacy of Plaxx as a fuel for power generation will have global impact. Mixed plastic waste is currently a worthless nuisance that affects all aspects of our eco-system. Converting MPW in to Plaxx and using it, as a fuel in an engine to generate power, will potentially affect the well being of many people across the globe. Given the spread of plastic products across the world, collecting waste plastic and selling it to the processor could potentially be a way of earning money in the poorer parts of the world, making a worthless nuisance into a valuable commodity.
-Waste managers; Companies who are interested in waste management and are examining methods that reduce the need for land fill sites and their long term effect as sources of environmental contamination
-Plant maintenance; Companies who are concerned with condition monitoring and are seeking improved understanding of wear and long term availability of capital equipment.
-Marine industry; Marine operators who will exploit the competitively priced Plaxx as a low sulphur alternative to HFO
-Operators of wind and solar farms will be better able to examine Plaxx fuel for their diesel generating sets for meeting sun light and wind generating variability whilst off setting some of green house gas emission by use of mixed plastic waste.
-The benefits of the work will be:
The research output will be in three broad areas; Engine performance, engine emissions and engine wear, in all cases related to Plaxx as a fuel. The producers and users of diesel engines will benefit from this work by developing a better understanding of the engine design and operation's effects on engine performance.
-Plaxx as a waste by-product fuel will be cheaper than diesel fuel delivered from refinery. An understanding of the behaviour of Plaxx as a fuel, particularly in terms of emissions when combusted in an engine will enable the power generator to examine the longer term consequences of its use as a fuel.
-A better understanding of engine wear as a consequence of using Plaxx will help develop models that can help in understanding of the long term effect of wear in capital intensive equipment and thus put in place wear mitigating strategies
-The societal benefits will be in terms of reduction of mixed waste plastic in land fill sites and use of Plaxx to generate electric power.
-The close monitoring of emissions and development of models that relate engine performance to emissions will be particularly useful in enabling an improved control of emissions particularly under varying load regimes.

Publications

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Description The engine trials has shown that Two streams of PLAXX, that is PLAXX 16 and PLAXX 30 can be used as substitutes for diesel fuel.
Further it appears that PLAXX 30 although containing wax particles might be a better substitute than PLAXX 16. Work with PLAXX 16 indicates that due to its low viscosity it may suffer from poor atomisation when ejected through the engine injector. These conclusions will need to be further validated with more analysis.
Exploitation Route The findings so far appear to show that PLAXX can be used as a substitute for diesel, however, the type of engine that would most benefit from this fuel is not clear.
So far on the single cylinder engine trials PLAXX 30 appears to be more suitable of the two streams.
However, due to the presence of wax particles either better filtering or heated fuel system may be required. This will have implications for the type of engine that would benefit from this fuel.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Construction,Energy,Environment,Transport