Many developers will claim that they are technology agnostic. BH EnergyGap is anything but technology agnostic, as this implies not caring about what actually gets built. BH EnergyGap is concerned that whatever technology is selected it has to be right for the job and give reliable performance over the life of the project. This means caring very much. BH EnergyGap pre-vets all proposed technologies for funder and operator approval. All the technologies being considered are proven, tried and tested, with appropriate reference plants in operation.
Reaching a definitive view on technology does not mean being inflexible, and BH EnergyGap works with its advisors and operators to ensure that the technology will work reliably with the waste stream being provided.
The technology sectors being considered by BH EnergyGap include:
Waste Processing and Materials Extraction
To enable the most efficient collection of waste, it is best to collect it mixed and then sort it into its constituent material streams. What is left over can then be used as a fuel for energy recovery. Deploying waste processing enables secondary materials such as metals and plastics to be extracted from the waste stream before the energy content is recovered. It also serves however, to convert the residual waste stream into whatever form is required for the subsequent energy recovery process.
Thermal Treatment
The most common method for extracting energy from waste, but can involve a range of different processes:
Combustion
This is the most commonly used to date and uses oxygen in the air to fully burn the waste. One of the advantages of moving grates is that it is possible to burn a wide variety of wastes without the need to pre-treat it. Fluidised bed can also be used and this has flexibility of use that the moving grate does not, but it is also necessary to prepare the waste before it enters the furnace.
Gasification
This heats the waste without enough oxygen present to enable it to burn, producing a syngas, which can then be combusted. It is necessary to pre-treat the waste before gasifying it, but the technology has more potential applications than combustion and may eventually open the door to a hydrogen economy and the use of fuel cells.
Pyrolysis
This decomposes the waste with no oxygen at all present, producing a char and pyrolysis oil. The process is probably best used with special single stream wastes.
All thermal treatment technologies provide the means for generation of electricity and/or providing heat for district heating or industrial processes. It sits comfortably alongside recycling if the waste management system is designed properly.
Anaerobic Digestion
Another means of extracting energy from waste, but it can only be used for organic wastes and sludges. The science of Anaerobic Digestion (AD) is complex and there are a number of types of process. They all generate a biogas, which can be used as a fuel in an internal combustion engine or even injected into the gas main as a substitute for natural gas. They also produce a digestate, the solids from which can be used as a soil supplement.
Bioethanol
Various technologies exist which can produce a diesel substitute from an assorted range of organic feed stock either by using fermentation or from the syngas of a gasification plant. These technologies are well known, but have not developed due to the volatility of bioethanol prices.
BH EnergyGap will update this page from time to time to bring the latest thinking on waste management and energy technologies.