--- title: "Generation expansion planning and load forecasting" subject: "Power Plant Design" chapter: 2 key: "semester_8/power_plant_design:generation-expansion-load-forecast" source: https://www.bctengineer.com/q/semester_8/power_plant_design/generation-expansion-load-forecast site: BCT Engineering --- # Generation expansion planning and load forecasting Power Plant Design · Chapter 2: Integrated System Planning in Design Approach - Asked in: 2078 Chaitra, 6 marks - Video: [Generation Planning Part 1](https://www.youtube.com/watch?v=4DSqspq7iYU) — Omkar Buwa - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/power_plant_design/generation-expansion-load-forecast - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-2 ## Question What do you understand by generation expansion planning? How does load forecasting effects generation expansion planning? ## Short answer Generation expansion planning (GEP) determines least-cost capacity additions to meet forecast load reliably. Load forecasting sets required capacity and timing, influences plant type (e.g., storage for winter peaks), and errors cause excess cost/spill or load shedding; accurate multi-scenario forecasts are essential. ## Answer **Generation expansion planning (GEP)** is the long-term planning of **what type**, **how much**, **where** and **when** new generating capacity should be added so that the forecast load is met at minimum total cost while satisfying reliability (LOLP, reserve margin), environmental and policy constraints. #### Steps in brief Load forecast → existing system and retirements → candidate plants → reliability criteria → alternative plans → production simulation → least-cost selection → sensitivity analysis. #### Effect of load forecasting on GEP The load forecast is the main input; every decision in GEP depends on it. 1. **Amount of capacity:** Forecast peak demand plus reserve margin gives the required installed capacity. A 5% error in a 3,000 MW forecast is about 150 MW, roughly one medium hydro plant. 2. **Timing:** The growth rate decides the year each plant must be commissioned; long lead-time hydro must be started years in advance. 3. **Plant type (mix):** The shape of the load curve decides the mix. A high base load needs ROR/base plants; a sharp evening peak needs storage, peaking ROR or pumped storage. Nepal's winter evening peak with low river flow calls for storage projects. 4. **Energy vs capacity:** Energy forecast (GWh) decides firm energy needs; seasonal pattern decides import/export. 5. **Location:** Regional forecasts influence where plants are sited. 6. **Cost and reliability:** | Forecast error | Effect on GEP | |---|---| | Over-forecast | Excess capacity, idle capital, energy spill, high tariff | | Under-forecast | Shortage, load shedding, costly import/diesel | 7. **Uncertainty handling:** Because forecasts are uncertain, GEP uses scenarios (high/base/low) and flexible plans. Thus, accurate load forecasting is essential for an economical and reliable generation expansion plan. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. GEP is long-term planning of A. only retirement dates B. what type, how much, where and when new capacity is added at minimum cost with reliability C. only operating schedule D. only fuel purchase Answer: B. GEP answers type, size, place and time under reliability, environmental and policy constraints. (Key point: GEP definition) 2. How does the load forecast set required installed capacity? A. Forecast peak demand plus reserve margin B. Forecast energy only C. Average load only D. Minimum load Answer: A. Installed capacity must cover peak demand plus reserve; a 5% error on 3000 MW is about 150 MW. (Key point: Capacity) 3. How does load curve shape affect plant mix? A. It has no effect B. Sharp evening peak needs storage/peaking/pumped storage; high base load needs ROR/base plants C. Peak always needs ROR D. Base load needs gas only Answer: B. Different load shapes call for base-load or peaking plants. (Key point: Plant mix) 4. What does under-forecasting lead to in GEP? A. Excess capacity and spill B. Shortage, load shedding and costly import/diesel C. Lower tariff D. Idle capital Answer: B. Too little capacity is built; over-forecast leads to the opposite problem. (Key point: Forecast error) ## Related in Power Plant Design - [Generation expansion planning procedure](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ageneration-expansion-procedure) — Power Plant Design, chapter 2, asked 3× - [Generation and distribution planning procedure](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aplanning-generation-distribution) — Power Plant Design, chapter 2 - [Need for accurate load forecasting](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aload-forecasting-importance) — Power Plant Design, chapter 2, asked 2× - [Transmission expansion planning in deregulated market](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Atransmission-planning-deregulated) — 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 - [Transmission expansion planning and applicability](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Atransmission-expansion-applicability) — Power Plant Design, chapter 2 ## Related in other subjects - [Demand forecasting steps at load center](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Ademand-forecast-load-center-steps) — Transmission and Distribution System Design, chapter 6 - [Methods of load forecasting](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Aload-forecasting-methods) — Transmission and Distribution System Design, chapter 6 - [Small area forecasting with load growth curve](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Asmall-area-load-growth-curve) — Transmission and Distribution System Design, chapter 6 - [Small area load forecasting method](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Asmall-area-forecasting-method) — Transmission and Distribution System Design, chapter 6