Hydrokinetic Power in Navigable Waterways William H. McAnally Northern Gulf Institute Sandra L. Ortega-Achury and James L. Martin Civil and Environmental Engineering Mississippi State University Trey E. Davis and Jeff Lillycrop U.S. Army Engineer Research and Development Center

In-stream Hydrokinetic Electric Power Turbines capturing the energy of naturally flowing water – stream flows, tidal flows, or wave motion – without impounding the water. Devicesplaced in tidal waters and non-tidal rivers 2 (Source: Bedard et al., 2006)

Power Generation Power generated proportional to the velocity cubed 3 (Source: Hydropower Reform Coalition, 2008) (Courtesy: Hydro Green Energy)

FERC Permits 4

Hydrokinetics: Pro Potential for adding 25K-30K MW to U.S. generating capacity Requires no new impounding dams Operations do not contribute to greenhouse gas emissions or other air pollution Aesthetically preferred to wind farms Contribute to energy independence 5

Hydrokinetics: Concerns Cost effective? Construction & Maintenance Impacts Potential effects on: – Physical environment – water level, flow, water quality, sedimentation – Navigation – safety and efficiency – Biotic environment – fish, migration, habitat 6

Physical Environment Example: Hypothetical Waterway Mass & Energy Conservation Eqns 7 VariableValue Discharge10,000 m 3 /sec Roughness Coefficient, n0.025 Length of Channel2,000 m Bottom Slope KE Coefficient1 Channel Width2,000 m Tailwater Depth Fixed3 m Extraction Loss Fraction0 to 30 %

Extraction of 10% KE One Cross-Section 8

9 Extraction of Various KE at 8 Cross-Sections:

Physical Environment Effects Hydrokinetic generators in tidal and non-tidal rivers can cause (positive or negative impacts): Decreased flow speeds Altered water levels Increased sediment deposition in the vicinity Altered salinity intrusion Altered water quality Altered transport patterns and habitats Scour around the structures Precise resolution of effects must be addressed by multi-dimensional numerical site-specific models. 10

Direct Navigation Effects Probability of Vessel Strike 11 Vessel Probability Distribution of Vessel Path X-Section View of Channel Distorted Horizontal Scale Area = Probability of right side excursion Defined Channel Hydrokinetic Installation Locations

Some Historical Data 936 vessel accidents in the Lower Mississippi River 1979 thru 1987: 207 collisions, 422 rammings, 297 groundings and 10 unknown.* Equals 0.32 Out-of- Channel accidents/ channel mile-year Applicable to hydrokinetic structure collisions? 12 * Blanc and Rucks (1996) Courtesy aolnews.com 2010

Simulated Vessel Passes Thru Turn 13 Corps of Engineers Simulator Can be used to generate vessel excursion probabilities.

Conclusions Hydrokinetic power offers a significant contribution to U.S. electricity needs. Do not contribute to greenhouse gas emissions and have less visual aesthetic impact than wind turbines. Benefit to cost ratio for power companies can be calculated. B/C ratio of hydrokinetic installations on public-interest include: – Decreased flow speeds & altered water levels – Localized bed scour & far field sediment deposition – Altered salinity intrusion in estuaries – Altered water quality – Altered habitats – Vessel accidents in navigation channels These cumulative changes plus site conditions will dictate whether a specific hydrokinetic generator is in public interest. 14

Interested? ASCE Coasts, Oceans, Ports and Rivers Institute Marine Renewable Energy Committee – Bil Stewart, Chair – MRE In-Stream Hydrokinetic Sub-committee – Jim VanZwieten, Jr., Chair Waterways Committee – Kelly Barnes, Chair – Navigation Engineering Sub-Committee – Bill McAnally, Chair 15

Contact Information William H. McAnally 16