Routing a 345 kV Collector for 800 MW Wind
A developer proposes an 800 MW wind farm in a rural region. The point of interconnection is a 345 kV substation 60 miles away. The utility's least-cost route crosses 8 miles of wetlands, 22 miles of prime farmland, and a ridge that is a tribal cultural property. A longer 72-mile route avoids the ridge and most wetlands but passes within 500 feet of 140 residences and crosses a state forest. A third option rebuilds 40 miles of an existing 230 kV corridor to 345 kV, but requires 18 months of outages and has limited capacity. The interconnection study assigns $310 million of network upgrades, with $190 million attributable to the project and $120 million to broader system benefits. The state requires a certificate of public convenience, an environmental impact statement, and tribal consultation. Construction season is limited to 6 months per year; the wind farm's PPA has a COD penalty of $1.2 million per month. The utility has a 2040 clean-energy mandate and a reliability need in the same area.
1. Select a route. Show the criteria and the reasoning.
Read the worked answer
Use a triple bottom line: capital and schedule cost, environmental and permit risk, and reliability. Route 1 is shortest, but 8 miles of wetlands, 22 miles of prime farmland, and a tribal cultural ridge create high permit and litigation risk. Route 2 is 12 miles longer, avoids the ridge and most wetlands, but has 140 residences within 500 feet, creating landowner and visual risk. The existing 230 kV rebuild avoids new right-of-way but requires 18 months of outages and may have limited capacity. A hybrid is likely best: use the existing corridor where it can be rebuilt without long outages, then a new segment following Route 2 to avoid the ridge and wetlands. Quantify: 12 extra miles at, say, $3 million per mile is $36 million; a 12-month delay at $1.2 million per month is $14.4 million plus lost PPA revenue. The cultural site is a red line and should be avoided. The 140 residences require mitigation, not avoidance. Select the hybrid with tribal consultation and route refinement to reduce residential impacts.
2. How should the $310 million network upgrade cost be allocated?
Read the worked answer
Separate direct interconnection cost from broader system benefits. The $190 million attributable to the project should be paid by the interconnection customer under the tariff, subject to any participant funding or clawback. The $120 million for broader system benefits should be allocated to beneficiaries, such as load that gains reliability or capacity, through the transmission rate, not automatically to the generator. Document the benefit study. If the utility's clean-energy mandate creates statewide benefit, the commission may socialize part, but it must find a rational nexus. Avoid gold-plating and re-run the power flow with and without the project.
3. What permit and schedule strategy would you recommend?
Read the worked answer
Start tribal consultation before filing; the cultural property is a schedule-critical issue. Use a single EIS with the hybrid as the preferred alternative and Routes 1 and 2 as alternatives. Conduct wetland delineation and cultural surveys early. Negotiate a COD extension or a delay recovery plan with the offtaker; do not assume the 6-month construction season can absorb a permit delay. Sequence construction: rebuild the existing corridor first to create capacity, then build the new segment. Commit to mitigation such as wetland restoration, agricultural reclamation, and visual screening. Do not begin construction before the certificate and EIS are final; the penalty is less costly than an enforcement action.