Enough annual gas, too little peak-day delivery
A gas-fired generator has a fuel contract but faces a transport constraint during the evening peak. The team must distinguish contracted volume, hourly delivery and usable inventory.
Permanent case linkYour task
Test whether the dispatch plan is fuel-feasible and compare a delivery uplift with electricity exposure. State what this simplified screen cannot approve.
Your role
Fuel-supply analyst supporting generation scheduling
Practice data & worked solution
Inventory must stay non-negative
Original synthetic three-hour generator schedule. Heat rate 9 GJ per electrical MWh; each row one hour. Initial accessible fuel inventory 300 GJ, with unrestricted withdrawal for this exercise. Pipeline delivery arrives during each hour. No minimum generation, start fuel, ramp limits, reserve inventory, gas price or other costs. Deliveries are already net of other customers; this is not a pipeline hydraulic model.
| Hour | Scheduled output MW | Pipeline delivery GJ | Electricity price AUD per MWh |
|---|---|---|---|
| 1 | 100 | 800 | 120 |
| 2 | 100 | 700 | 250 |
| 3 | 100 | 800 | 150 |
Your analysis
- Calculate hourly fuel requirement and inventory if the schedule is attempted. Identify the first infeasible hour.
- Reduce only the infeasible hour's generation enough to preserve zero ending inventory. Calculate energy and gross receipts forgone.
- Add 50 GJ of delivery in each hour. Recalculate inventory and state the maximum incremental delivery spend justified by the recovered gross receipts before other costs.
Worked solution
Peak delivery constraint
Each 100 MWh hour needs 900 GJ. Attempted closing inventory is 200, 0 and −100 GJ. The third hour is infeasible even though the first two are feasible. A negative inventory is a diagnostic failure, not an operating option.
Feasible schedule
With no starting inventory in hour three, 800 GJ supports 800/9 = 88.89 MWh. Generation falls by 11.11 MWh, with about A$1,666.67 gross receipts forgone at A$150/MWh. Total energy becomes 288.89 MWh. Additional fuel price and variable generation costs would change the margin effect.
Delivery uplift
With deliveries 850, 750 and 850 GJ, closing inventory is 250, 100 and 50 GJ. All 300 MWh can be generated. The recovered gross receipts are A$1,666.67; spending this entire amount leaves no allowance for extra fuel or other costs. If charged uniformly for all 150 additional GJ, the gross ceiling is A$11.11/GJ. Verify transport and withdrawal rights before scheduling.
Review your response
- Units: heat rate converts electrical MWh to GJ, not the reverse.
- Feasibility: each hourly inventory is checked, not only the daily sum.
- Economics: gross receipts are not labelled incremental profit.
- Evidence: annual adequacy forecasts do not demonstrate site-specific hourly fuel deliverability.
This checklist supports self-review. No tutor marking or independent credential is included.
Related topics 4
Sources & evidence
All figures are original teaching inputs, not observations or published forecasts. The official source supplies industry context, not this dataset. Source link checked 17 October 2026. Use the GSOO for adequacy context; actual scheduling requires transport contracts, nominations, storage withdrawal limits and plant heat-rate data.
AEMO Gas Statement of Opportunities