Document Type : Original Article
Authors
1 Dept. of Environmental Science, College of Science, University of Zakho, Duhok, Iraq.
2 Dept. of Computer Science, College of Science, University of Zakho, Duhok, Iraq.
10.22044/rera.2026.17708.1538
Abstract
The Gali Zakho Tunnel in Dohuk, Iraq consumes 12,704.44 kWh every day. Lighting, ventilation, safety monitoring, and control systems operate continuously. Power failure is a life-safety event. This study designs and optimizes a grid-connected hybrid renewable energy system (HRES) for the tunnel using HOMER Pro, operating strictly within the Kurdistan Region of Iraq's current grid policy: a purchase tariff of $0.129/kWh, zero export credit for surplus generation, and monthly net metering with no carryover. Five configurations were evaluated against a hard zero annual capacity shortage constraint. Two met it. Case-B (PV–Generator–Grid, 5,558 kW PV) is the economic winner: NPC $3.28M, COE $0.0187/kWh, 68.5% renewable fraction. The standby diesel generator burns zero fuel under normal conditions and activates only if both the grid and PV fail simultaneously. Case-C (PV–Battery–Grid, 5,768 kW PV) is the environmental winner: NPC $5.27M, COE $0.0380/kWh, 84.1% renewable fraction, 78.6% CO2 reduction versus grid-only. A two-layer battery framework separates daily economic cycling (10.4 hours) from a locked emergency reserve of 2,954 kWh (~5.6 hours). Combined, the system sustains uninterrupted tunnel operation for approximately 16 hours without any external input. Comprehensive sensitivity analyses on discount rate (0.95%–10% real), battery cost ($175–$300/kWh), and land/civil works ($0–$250k) confirm that both configurations remain economically viable across all tested scenarios. Both configurations are fully reliable and buildable today under regulations as they currently stand, without waiting for policy reform.
Keywords
- HOMER Pro
- Constrained grid export
- Two-layer battery reliability
- Critical infrastructure
- Tunnel electrification
Main Subjects
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