--- title: "Parameters for planning and sizing a plant" subject: "Power Plant Design" chapter: 2 key: "semester_8/power_plant_design:plant-sizing-parameters" source: https://www.bctengineer.com/q/semester_8/power_plant_design/plant-sizing-parameters site: BCT Engineering --- # Parameters for planning and sizing a plant Power Plant Design · Chapter 2: Integrated System Planning in Design Approach - Asked in: 2070 Bhadra, 8 marks - Video: [Load curve and Load duration curve in power Plant.](https://www.youtube.com/watch?v=x_rFnNpeP2U) — Unique Series - Civil Mantraa - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/power_plant_design/plant-sizing-parameters - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-2 ## Question Discuss the important parameters in planning, selecting and sizing of a plant on the basis of load/demand forecast, economics and system planning. ## Short answer Key parameters are peak demand and growth rate, energy demand, load curve shape and load factor; economic factors like capital cost, LCOE, NPV/IRR, plant factor, tariff; system planning factors like reserve margin, unit size relative to system, number of units, transmission availability, generation mix, stability. Final size gives least cost per kWh while meeting reliability. ## Answer Planning, selecting and sizing a plant means deciding the **type**, **installed capacity**, **number of units** and **commissioning time** of a new plant so that it fits the forecast demand, is economically viable and suits the overall system plan. #### 1. Parameters from load/demand forecast - **Peak demand (MW) and growth rate:** decide how much capacity is needed and when. - **Energy demand (GWh):** decides required annual and firm energy. - **Load curve shape:** base, intermediate or peak load. Base load suits ROR/thermal; peak load suits storage, PROR or gas turbines. - **Load factor:** a high load factor favours base-load plants with high capital and low running cost. - **Seasonal pattern:** in Nepal winter evening peak with low river flow favours storage/PROR plants. - **Location of load centres:** affects transmission cost. #### 2. Economic parameters - **Capital cost** per kW and **O&M/fuel cost** per kWh. - **Levelised cost of energy (LCOE)** and comparison with alternatives. - **Economic indicators:** NPV, IRR (typically above 10–12%), B/C ratio, payback period. - **Plant factor / capacity factor:** higher plant factor lowers cost per kWh. - **Tariff / PPA rate** (e.g. NEA wet and dry season rates), royalty and taxes. - **Financing:** debt–equity ratio, interest rate, construction period. #### 3. System planning parameters - **Reserve margin and reliability** (LOLP, spinning reserve). - **Unit size relative to system:** loss of the largest unit must not endanger the system; usually unit size below about 10% of system peak. - **Number of units:** decided by flow variation (FDC), part-load efficiency, maintenance and transport limits. - **Transmission availability:** voltage and distance to nearest grid substation. - **Fit in generation mix:** hydro–thermal–solar balance, firm power need. - **Stability:** short-circuit ratio, inertia, voltage support. #### 4. Site and technical parameters (for hydro) Design discharge (e.g. Q40–Q65 from FDC), net head, turbine type, sediment, geology, access, environmental flow (riparian release). #### 5. Environmental and social parameters Land acquisition, resettlement, emissions, river ecology, local benefit sharing. The final size is the one that gives the least cost per kWh to the system while meeting reliability and constraints. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which plant type suits a high load factor? A. Base-load plants with high capital and low running cost B. Peaking plants only C. Diesel only D. None Answer: A. High load factor spreads capital cost over many kWh, favouring base-load plants. (Key point: Load factor and plant type) 2. Which are economic indicators for plant selection? A. Load flow and fault level B. NPV, IRR, B/C ratio, payback and LCOE C. SAIFI and SAIDI D. Frequency and voltage Answer: B. Economic viability is judged using NPV, IRR (above 10-12%), B/C ratio, payback and LCOE. (Key point: Economic indicators) 3. What does the number of units depend on? A. Only tariff B. Colour C. Only voltage D. Flow variation (FDC), part-load efficiency, maintenance and transport limits Answer: D. Number of units is decided by flow variation, part-load efficiency, maintenance and transport limits. (Key point: Unit size and number) 4. Design discharge for hydro is usually taken from the FDC as A. Q100 B. Q40-Q65 C. Q0 D. Q5 only Answer: B. The text gives Q40-Q65 from the flow duration curve. (Key point: Design discharge) ## Related in Power Plant Design - [Define load forecast](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Adefine-load-forecast) — Power Plant Design, chapter 2, asked 3× - [Generation expansion planning and load forecasting](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ageneration-expansion-load-forecast) — Power Plant Design, chapter 2 - [Power system planning and grid integration](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aplanning-deregulated-grid-integration) — Power Plant Design, chapter 2 - [Power system expansion planning for a utility](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aexpansion-planning-national-utility) — Power Plant Design, chapter 2 - [Factors affecting system expansion planning](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Asystem-expansion-factors) — Power Plant Design, chapter 2 - [Accurate load forecasting and system security](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aload-forecasting-benefits-security) — Power Plant Design, chapter 2 ## Related in other subjects - [Forecast CFL demand for next five years](https://www.bctengineer.com/question.md?key=semester_6%2Fengineering_economics%3Aforecast-cfl-demand-five-years) — Engineering Economics, chapter 1 - [Why schedule is important in planning](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Aschedule-importance-planning) — Project Engineering, chapter 3 - [Why risk analysis is important in planning](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Arisk-importance-analysis-planning) — Project Engineering, chapter 5 - [Combined plant layouts, performance and economics](https://www.bctengineer.com/question.md?key=semester_7%2Fpower_plant_equipment%3Acombined-layout-economics) — Power Plant Equipment, chapter 8