Near-optimum cost minimisation of transporting bioenergy carriers from source to intermediate distributors

[摘要] ENGLISH ABSTRACT: The world is facing an energy crisis with worldwide energy consumption rising at analarming rate. The effects that fossil fuels have on the environment are also causingconcern. For these two reasons the world is determined to find 'cleaner', renewableand sustainable energy sources.The Cape Winelands District Munisipality (CWDM) area has been identified as thestudy area for a bioenergy project. The CWDM project aims to determine thepossibility of producing bioenergy from lignocellulosic biomass, and transporting it aseconomically as possible to a number of electricity plants within the study area.From the CWDM project a number of research topics were identified.The aim of this thesis is to determine the best location for one or more processingplants that will maximise the potential profit through the entire system. This isachieved by minimising the overall life cycle cost of the project. It takes into accountcosts from establishing and maintaining the crops, harvesting, transportation,conversion and generation; with a strong focus on the transport costs.In conjunction with a Geographical Information Systems (GIS) specialist and takinginto account various factors such as electricity demand, heat sales and substationlocations, 14 possible plant locations were identified. The possible supply points foreach of the 14 plant locations were then analysed by GIS again to yield data in termsof elevation, road distances and slope.The transport costs were calculated using the Vehicle Cost Schedule (VCS) from theRoad Freight Association (RFA) and fuel consumption calculations. It takes intoaccount slope, laden and unladen transport and considers different transportcommodities. These calculations together with the other associated costs of the life cycle are thencombined with the results of the GIS into an EXCEL file. From this a transportationoptimisation model is developed and the equivalent yearly life cycle cost of each ofthe 14 demand points are minimised by means of LINGO software. Initially runs weredone for 2.5 MW capacity plants. From the high profit areas identified here, a singlearea was chosen and further runs were done on it.These runs were performed to determine the effect of different plant capacities onthe life cycle costs, as well as how it affects the farm gate price that can be paid tothe farmer. It also determined the effect of farmer participation at different plantcapacities.The results indicate that it is currently possible to pay a farmer between R 300.00and R 358.00 for a ton of biomass. It also revealed that with higher participationfrom farmers in the CWDM project, lower costs and higher farm gate prices willresult, since the transport costs will be lower. Although all the costs within the lifecycle are variable over time, the transport cost is the only cost that varies spatiallyand this will have a major effect on the overall system cost.The thesis found that generating electricity from woody biomass is feasible for allareas that were considered as well as for all variations considered during thesensitivity analysis. For the recommended plant size of 5 MW the transport of logswill be optimum.

[发布机构] Stellenbosch University