Feasibility Study Waste to Water

Transcription

1 Feasibility Study Waste to Water BASE TECHNOLOGIES GmbH Steinsdorfstraße München Tel Fax

2 1. Approach of the Study The target of the project Waste to Water (W2W) was to evaluate the situation in Malta in the fields of waste recovery and water desalination and to work out a promising concept for the future. Therefore, BASE TECHNOLOGIES GmbH (BT) investigated the opportunity of energetically using the waste in Malta in order to produce drinking water through desalination. The idea was to find a solution for Malta but also to work out technical and economical feasibilities which can be translated to other countries and regions that face challenges similar to those in Malta. The illustration below shows the technical approach from waste to water. relevant share for incineration turbine electrical grid reverse osmosis waste in Malta water desalination waste incineration steam, heat heat exchanger thermal desalination Fig. 1: Illustration of the technical Waste to Water approach Current waste and water situation in Malta The main waste streams in Malta currently go to the Maghtab landfill, which has only very limited further capacities. Only a small amount is pre-treated in the mechanical biological treatment plant (MBT) of Sant Antnin. Therefore a new and sustainable waste concept has to be elaborated The public drinking water (33 mil. m³/a) is produced from ground water (15 mil. m³/a) and from three desalination plants using reverse osmosis technology (18 mil. m³/a). The electric energy for these plants is produced in oil driven power plants. The corresponding oil consumption is about 27 mil. l/a. Available waste quantities in Malta As a basis for the study, BT investigated the different available waste fractions in Malta and their usability for waste incineration in general. The usable quanti BASE TECHNOLOGIES GmbH Feasibility Study Waste to Water 1

3 ties were assessed according to their energetic content (heating value) in order to determine possible incineration technologies and plant settings. Based on the current and predicted future available waste fractions in Malta, two different possible waste scenarios have been evaluated. In the Minimum Case scenario, 107 kt/a of waste are available at an average heating value of 12,7 MJ/kg. It assumes that 100 % of the domestic waste fraction will be handled in MBT leading to a higher Refuse Derived Fuel (RDF) fraction and a higher overall heating value. The Base Case scenario just operates with the already existing MBT in Sant Antnin and comprises 200 kt/a at a heating value of 10,3 MJ/kg. Technologies for waste incineration For waste incineration, several basic technologies were considered: Grate Firing (GF) and Fluidised Bed Combustion (FBC) as the mainly used technologies worldwide but also rather new technologies such as Pyrolysis and High Temperature Gasification. However, the new technologies have been discarded in the further considerations due to risks of low maturity. Whereas FBC can perfectly be used for the incineration of homogenous fractions, GF allows the combustion of rather non-homogenous materials (waste situation in Malta). Therefore, the chosen technology for the incineration was GF. For both waste quantity scenarios, two incineration plant configurations were considered: One with maximum electrical energy production for membranebased desalination technology and two with additionally coupling out steam for thermal desalination. BT also looked at a heat/steam only scenario, however, due to the low overall efficiency it was not subject to further considerations. Technologies for water desalination For water desalination, there are basically two major technologies, i.e. membrane methods such as Reverse Osmosis (RO) and thermal methods such as Multi Effect Distillation (MED) and Multi Stage Flash evaporation (MSF). For RO, the electrical energy coming from the GF plant can be applied and for MSF or MED, the electrical and thermal heat from the GF plant can be used. BASE TECHNOLOGIES GmbH Feasibility Study Waste to Water 2

4 Cases derived Pertaining to the technology considerations before, in total, six different cases were derived: Desalination technology Waste quantity RO RO Incineration technology: GF MED MSF + RO MSF MED + RO 107 kt/a Heating value: 12,7 MJ/kg Case- name: 107 Case -name: /MED 107 Case -name: /MSF kt/a Heating value: 10,3 MJ/kg Case- name: 200 Case -name: /MED 200 Case -name: /MSF 200 Table 1: Incineration cases Depending on the case, different total water quantities can be derived. Due to the great efficiency the two cases applying RO only are advantageous in terms of water output. However, the quality of the thermally desalinated water is much better in terms of having a lower value of Total Dissolved Solids (TDS), than water gained from RO plants. The amounts of water output per case can be seen in the following table: Desalination technology Waste quantity RO RO Incineration technology: GF MED MSF + RO MSF MED + RO 107 kt/a Heating value: 12,7 MJ/kg /MED /MSF kt/a Heating value: 10,3 MJ/kg /MED /MSF Table 2: Water desalination cases (water output amounts in million m³/a) BASE TECHNOLOGIES GmbH Feasibility Study Waste to Water 3

5 Economic evaluation In addition to the total amount of water output, the economical situation was considered. The summarised outcomes of the economic calculation, determined as remaining waste disposal costs after water sales are illustrated below. Case 107 /MED 107 /MSF /MED 200 /MSF 200 spec. waste disposal costs [ /t] Table 3: Remaining waste disposal costs The relatively best cases are those using only RO desalination technology. Location assessment BT assessed the island of Malta in order to find suitable spots for a plant (combination). This was conducted according to the pattern below. Prohibitive* criteria Residential area Beaches Ground water protection area Limiting* criteria Distance to residential area Distance to coastline Promoting criteria Main roads Power grid Water network Remaining promotive locations will be subject to further assessment Reasons are to be balanced very carefully * Prohibitive and limiting criteria were not finally differentiated in the current project status Fig. 2: Pattern for site evaluation BASE TECHNOLOGIES GmbH Feasibility Study Waste to Water 4

6 In the following illustration, the result of the investigation and the identified spots are illustrated. Maghtab landfill: existing infrastructure Cirkewwa: waste arrives from Gozo Marsa: existing power plant Positive locations Special consideration 8 km Delimara: existing power plant Fig. 3: Potential sites The evaluation of potential sites was carried out as a preliminary investigation. Further facts and figures have to be put into account when assessing the locations in detail. Contractors and investors / financing and subsidy options The outcome of the assessment of opportunities to integrate contractors and investors into a major project like W2W were several potential partner (-groups) for each project phase and for each specialised project task. In this phase, also potential financing and subsidy options for W2W were subject to investigations. According to the BT findings, several EU subsidy programmes and institutions were investigated for which W2W is likely to qualify in the event of a project realisation. One of them was the European Investment Bank (EIB) for reimbursable investment support. For non-reimbursable subsidies, in turn, the European structural and cohesions funds could be applicable, also because two programmes are already running in Malta: The programme Investing in Competitiveness for a Better Quality of Life (running under the Convergence Objective) and the programme Mediterranean Programme (running under the European Territorial Cooperation Objective). BASE TECHNOLOGIES GmbH Feasibility Study Waste to Water 5

7 Measures to increase the acceptance of the population Finally, measures to increase the population s acceptance were identified. Therefore BT accumulated positive aspects of W2W and separated them in different argumentative blocks (i.e. environmental arguments, energetic arguments, economic arguments and legal arguments). These arguments should be integrated in a comprehensive marketing PR-campaign for W2W, executed over all project phases from planning to regular operations of the plant. BT therefore illustrated examples for communication approaches of an incineration plant operator in Nuremberg (Germany), who for instance, publishes the plant s flue gas values on its website regularly. Exportability of the concept W2W The study W2W was concluded with an assessment of the ideas exportability to other (Mediterranean) regions and countries. The results of this investigations were, that basically, the technology combination of waste incineration and desalination plants (RO and / or MSF or MED) is transnationally highly feasible from a technical point of view as well as under economical and ecological considerations. However, the optimal country or region wise plant configuration has to be set up according to the respectively given circumstances. BASE TECHNOLOGIES GmbH Feasibility Study Waste to Water 6

8 Conclusions of the Study The realisation of W2W, particularly for an island like Malta, bears strong benefits. The study shows, that there are great opportunities to directly align resource and energy streams and to develop a sustainable comprehensive approach in favour of the Maltese people and of the environment. Summarising, the essential conclusions of the feasibility study are: W2W is the ideal concept to solve waste and water issues in Malta in an ecologically and economically sensible way. By energetically using the waste, ~ m³/a, respectively 100 % of the desalinated drinking water can be produced in Malta. The concept of W2W is technically feasible and is capable to substitute approximately litres of fossil oil every year. W2W contributes to the fulfilment of EU legislations for waste disposal and clean energy production. There are suitable locations in Malta for a W2W plant. The concept can be translated to other (Mediterranean) regions with similar issues on waste and water by technically amending the plants to the respectively given conditions. clean eaneded flue gas 240 kg combustion residues volume reduction 1,000 kg of % waste 21 kg additional substances W2W plant 50 kg dust and boil iler slag 90,645 l drinking water* 220 kg construction material (civil eng.) 20 kg metals mining (final disposal) air *considering technology from scenario 200 of this study Fig. 4: Summarising mass and water balance of a W2W plant in Malta BASE TECHNOLOGIES GmbH Feasibility Study Waste to Water 7