ASK THE EXPERTS: Microhydro System Permitting

Unlike PV systems, hydro permitting can require a three-line (rather than one-line) wiring schematic.
Aerial image of a site, with the existing dam, wheelhouse, and location of the proposed turbine.
Environmental Resource Mapper image of the site.

I read “Grid-Tied Microhydro in New York State” (HP183) and am curious about required permits for microhydro systems in New York, where I live, and your dealings, if any, with local building inspectors, as well as state and federal regulators. The stream on my property is apparently too small to be of concern to state environmental authorities, but what has been your experience dealing with regulators?

David Noland • via email

All energy systems require permits from government agencies. Even off-grid systems are held to National Electrical Code (NEC)  standards and are subject to inspections from local authorities having jurisdiction (AHJs). I’ve found that obtaining permits for microhydro-electricity systems can be particularly difficult. Because of these challenges, many renewable energy installation companies shy away from installing microhydro systems (and many DIYers fly under the radar, hoping to avoid being caught). Here are some tips for navigating a smooth path through a successful permitting process.

My experiences permitting microhydro systems have been limited to New York State. Other state and local guidelines may differ, but there are enough similarities to draw parallels. Because microhydro systems are custom designs, you may experience a different permitting process for each system.

  • Draw a site plan and three-line electrical diagram of the system
  • Obtain an electrical permit from the town or county building or planning department
  • Submit information for other required permits and applications. These may include: an application to your local utility for interconnection, state environmental permits, and Federal Energy Regulatory Commission permits.

Electrical Permits. Because these are electrical systems, all raceways, conductors, power electronics, and balance-of-system components must be installed according to NEC guidelines. The first four chapters of the NEC apply to all electrical installations; the later chapters address special scenarios. There are specific sections for PV (Article 690) and wind (Article 694), but none specific to microhydro systems. Since microhydro systems function similarly to small wind systems—with diversion controls and loads for turbine control—Article 694 can be used as a working document for NEC compliance.

Because microhydro systems are rare, I generally spend more time during an inspection explaining the system and how it operates than defending some particular nuance of the installation. At the inspection, I hand the inspector an “as-built” three-line diagram— and wait for questions to arise.

The three-line diagram may also be submitted as part of a packet for the local utility, if you intend to grid-tie your microhydro system. In New York, the Public Service Commission (PSC) regulates interconnected devices operating in parallel with the grid. Form K and Appendix B of the Standard Interconnection Requirements require a line diagram, inverter commissioning procedures, the inverter’s UL 1741 compliance documentation, a site map, a disconnect plan, and specification sheets for the inverter and microhydro turbine. Many of these documents will be used for obtaining environmental permits as well.

Environmental Permits. In New York, streams fall under the purview of the New York Department of Environmental Conservation (NYSDEC). Under the State Environmental Quality Review (SEQR) Act, the NYSDEC requires an Environmental Impact Assessment for all microhydro systems. During the project’s design phase, I generally contact the NYSDEC and speak with their wetlands permitting staff. Like me, they are interested in preserving water quality, but many also have a bent toward sustainability and renewable energy. I have found them to be willing to walk a site with me to discuss intake and tailrace locations, as well as identify potential penstock corridors. Immediately after walking a site, I complete an Environmental Assessment Form (EAF), using NYSDEC’s GIS-based online EAF mapping tool. The output from this mapping tool is a three-page EIA form that provides information regarding the site’s threatened or endangered biota, wetland status, and other critical environmental variables. Completing the form requires property tax map parcel data, a project narrative, and the project’s interactions with the water body (e.g., water extraction, discharge, and excavation activities).

In addition to the EIA form, the Environmental Resource Mapper (ERM), another GIS-based interactive tool, must be used to create a report that provides an overview of the water body standard and classification, the site’s National Wetlands Inventory categorization, and identification of rare or endangered biota. If the site is designated a “C(T)” or higher (designated as “protected streams”), a Joint Application Form (JAF) must be completed. The JAF must include site photos and detailed narrative describing stream bank disturbances, fill or excavations, erosion mitigation plans, and sequence of construction activities. Using the proper terminology is important (for example, “banks” may have a very specific definition related to high water lines). The JAF is concurrently submitted to the NYSDEC, the Army Corps of Engineers, the Office of General Services, and the Department of State.

FERC Permits. The last hurdle for microhydro permitting also tends to be the highest. The Federal Energy Regulatory Commission (FERC) regulates all hydropower installations, with little distinction between multi-MW and sub-kW systems. FERC has jurisdiction over navigable waters and their tributaries (which translates to every stream in the United States) and grid-interconnected systems. FERC’s Low Impact Hydro program is partitioned into several regions of the United States, with a single contact for all correspondence within the region. Visit the FERC “tips” website to find your region’s contact person. There are many documents on the FERC page that provide permit process information. At a minimum, you’ll need to submit:

  • State fish and wildlife permitting documents
  • A complete civil drawing and narrative that details the intake, penstock, power house, and tailrace, including dimensions and materials
  • A full electrical diagram with a narrative describing the system’s overspeed control and operation at varying water levels
  • Full engineering drawings (both plan and profile) of any impoundments affected by the project
  • Civil and electrical site maps.

Many of these materials have been produced during the previous steps—you’ll just need to assemble them all together. FERC often takes months to issue permits—microhydro systems are not simply shrugged off and FERC staff must work with you to make sure their requirements are satisfied.

Phil Hofmeyer • Associate Professor of Renewable Energy, SUNY, Morrisville, New York

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