The first steps in the hydropower project cycle: Initial investigations and feasibility studies 12 September 2013 Bruce Taylor
Introduction Objectives of early stage studies Tools and methods Case study from PNG Key messages
Early stage hydropower investigations DG 0 Decision to initiate a formal project DG 1 Decision to start full feasibility study DG 2 Decision to continue to develop the project DG 3 Final investment decision DG 4 Handover, acceptance, closeout Phase 0 Baseline data Phase 1 Prefeasibility/ concept Phase 2 Full feasibility study Phase 3 Development Phase 4 Implementation Phase 5 Operation Facilitation and planning of business case Develop and build - implementation Early stage investigations
The aim of early stage investigations is to identify and quantify project risks to ensure good decision making
Preliminary studies: progressive steps Baseline Consists of all available data and information that exists for the basin and can be used to identify risks. It may be collected for hydropower or other purposes (e.g. mineral exploration, census, flood prediction, environmental survey). Concept - To gain the preliminary understanding of project scale and economics, usually a desktop analysis. Hydrological assessment based on existing data (e.g. rainfall data). reliminary risk identification.
Pre-feasibility: Desktop & field investigations to quantify risks and identify show-stoppers. Refine the project layout and project economics to an accuracy of approx. 15%~-35% Feasibility: Detailed quantification of risks to refine project design and costing. Bring the project economics to an accuracy 10%~-15%
There are many tools and methods available for risk investigations Examples of geological risk assessment tools and methods Non intrusive investigation methods Field Geological Investigations
Case study from PNG Concept & Pre-feasibility PNG Hydro Power Project preferred arrangement Surge Shaft Preferred Powerhouse Site Dam Site 10.3 Km tunnel No road access Mineral exploration to north From concept study: potential high geological risk = tunnel rock hardness cost of tunnel boring
Overview of methods used to determine risk Power Station Power Station sites selected using LiDAR imagery Site considered low risk to project at this early stage Field investigation by geologist and dams engineer confirmed low risk. Tunnel Alignment Tunnel Alignment selected using LiDAR imagery Considered high risk to project at this stage due to lack of geological data and potential high cost of tunnel boring Subsequent geological mapping and review of mineral exploration data concluded low risk to project for cost of tunnel boring.
Investigation methods: Geological mapping & interpretation of acquired data Using information from all available sources and suitable expertise can avoid the need for intrusive and more expensive survey methods
Investigation methods cont.. Dam Site Dam site selected using LiDAR imagery and field visit by dam engineer and geologist Considered high risk to project at this early stage following recognition of porous rock (vesicular basalt) Subsequent river gauging's revealed a 10% water loss around dam site. Dam site required follow- up drilling investigations to understand water loss.
Investigation methods used - geological Drilling program revealed: Broad area of vesicular basalt around dam site. Potential for extensive subsurface water loss at full reservoir level Dam Site remains a high risk to project Next phase of feasibility study: Trial grouting curtain on right abutment
Key messages early stage studies Aim to minimize risk at an early stage in the project cycle Need to identify & quantify all types of risk: hydrological, geological, social, environmental, political, financial etc. *(We have just looked at geological and hydrological risks) Utilise all available methods of investigation and all available information to assist in decision making