BREAKTHROUGH STUDY PROVES RIVER ENERGY SAFETY

An Estimation Of Survival And Injury Of Fish Passed Through The Hydro Green Energy Hydrokinetic System, And A Characterization Of Fish Entrainment Potential At The Mississippi Lock And Dam No. 2 Hydroelectric Project (P-4306) Hastings, Minnesota; Final Report
December 2009 (Normandeau Associates)

SUMMARY
This is a fish story. It is a big story about little fish. It is a big story because the little fish didn’t get caught.

One of the up-to-now unproven things preventing further growth in the wave-tidal-current energy industry that is developing the ability to turn the kinetic energy of moving water into electricity (hydrokinetics), which could supply 10%-to-25% of the nation’s electricity, is its safety in the underwater environments where it must necessarily live.

The Federal Energy Regulatory Commission issued a license to Hydro Green Energy (HGE) to install the first U.S. hydrokinetic turbine to capture the flow of the Mississippi River and turn it into electricity in December 2008. The license required a “Fish Entrainment and Survival Monitoring Plan.”

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A Fish Survival and Injury Study of tagged fish that passed through the flowing waters captured by the HGE current energy turbine between June 5 and 11 was completed on June 13, 2009, with careful attention to proper tagging and handling methods and estimates of fish survival, injury and predation.

Summary of results: The evidence suggests a mortality of 193-to-636 fish per year due to entrainment of fish caught up in the water flowing past and through the turbine. Mortality of game fish by entrainment into the HGE hydrokinetic turbine is estimated at 4-to-12 white bass, 1-to-5 channel catfish, and 0-to-2 largemouth bass per year per turbine.

Conclusion (the scientific way to describe this result): The HGE river current turbine has had “little if any considerable impact” on Mississippi River fish. populations in the vicinity of the Mississippi Lock and Dam No. 2 Hydroelectric Project.

The potential is enormous. (click to enlarge)

This landmark study demonstrates that fish, which regularly frustrate a segment of the population that can think of nothing better to do in this nation’s protected paradises than pursue them with a stick and string, also have the instincts to avoid getting chopped up in whirling blades along their way.

Experts who have studied the hydrokinetic potential in U.S. oceans, lakes and rivers estimate there is up to a quarter of the nation’s power consumption available. That free, clean electricity near the coastal population centers where it is needed most, is now demonstrated likely to do little harm to the marine populations into which it must be built.

Next the hydrokinetic energies (wave, tidal and current) must demonstrate their capacity to cohabit with humans although, since they have so much to gain from the relationship, it might be incumbent on humans to work a little at the relationship.


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COMMENTARY
Hydro Green Energy’s hydrokinetic power system is being tested adjacent to the Mississippi Lock and Dam No. 2 Hydroelectric Project near Hastings, Minnesota. It is capturing the flow of Mississippi River current and turning it into electricity. HGE has similar technology designs to capture tidal and ocean currents.

Unlike existing and familiar hydroelectric power plants at the test site and on rivers around the nation and the world, HGE’s turbines capture the river’s energy without immensely costly dams, impoundments, or conduits. The HGE hydrokinetic 3-blade turbine, a first of its kind design, is suspended below the water’s surface and absorbs energy with the current’s flow along its horizontal axis.

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One of the reason’s for its safe performance may be that the 3 blades, covering a 12-foot diameter, spin at only 21 RPM, the slowest blade turning speed in the hydrokinetic industry. When the water is flowing at 3.5 meters per second, the HGE turbine can continuously turn out 100 kiloWatts of electricity. The whole turbine is ~24 ft long by 15 ft wide by 15 ft deep.

The U.S. Army Corps of Engineers’ (USACE) Mississippi Lock & Dam No. 2 was built in 1930 spans 722 feet (220 m) of the river and has 19 tainter gates. A wide earthen dam on the river’s west side completes the river traverse. It is capable of producing ~4.4 megawatts of electricity with a capacity factor (the time it produces its capability) of ~80%.

The City of Hastings and Hydro Green Energy operate the hydrokinetic power equipment. The City committed to allowing the dam to let through a current flow to the turbine to test its impact. USACE records demonstrate the commitment was fulfilled, making the test results valid.

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The objectives of the Normandeau Associates study were to:
(1) estimate the survival/injury of fish passing through the hydrokinetic unit;
(2) estimate predation; and,
(3) characterize entrainment potential.

These goals were accomplished through careful tagging and record keeping, according to the established standards of such environmental impact studies. There appear to be no questions regarding the Normandeau Associates methodology.

The objectives of the study were met. A combination of high recapture and control survival rates made it possible to use a relatively small number of fish without any loss of precision. Survival (including predation) and injury for small-sized (yellow perch and bluegill) and large-sized (channel catfish, smallmouth buffalo, and bigmouth buffalo) fish that went through the HGE turbine were estimated within specific reliability criteria and met established standards. Predation was not observed. The results are thought to offer an accurate estimate of impact to fish.

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Summary of results:

(1) For yellow perch, bluegill, adult channel catfish, smallmouth buffalo and bigmouth buffalo, both the treatment and control groups were recaptured at over 95%.
(2) For yellow perch, bluegill, and adult channel catfish, survival of the turbine was very nearly 100%. For smallmouth buffalo and bigmouth buffalo, survival of the turbine was 100%.
(3) The desired ability to estimate survival of the turbine was exceeded.
(4) None of the small- or large-sized fish examined displayed turbine blade injuries.
(5) No direct or indirect evidence of predation was found.
(6) The evidence suggests a mortality of 193-to-636 fish per year due to entrainment of the fish by the water in the turbine’s flow. Mortality of game fish by entrainment in the HGE hydrokinetic turbine is estimated at 4-to-12 white bass, 1-to-5 channel catfish, and 0-to-2 largemouth bass per year per turbine.

There was no incidence of turbine blade-inflicted injuries. One yellow perch was injured by the chain-driven, energy-transfer mechanism in the turbine but the study identification tags likely caused the injury.

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The tags were not thought to affect the study’s findings.

Tagging and tag-removal could cause injury but had “minimal cumulative effects.”

Lab studies suggest fish could be harmed by colliding with the turbine if water speed was great enough but that is unlikely in the HGE turbine’s vicinity.

The design of the HGE turbines, the study concluded, was conducive to minimizing harm to the fish in several ways: (1) More than 3 blades could create dangers; (2) A smaller blade runner diameter might be more threatening to the fish; (3) Gaps at the turbine blade tip and turbine hub pose little risk; (4) The absence of an operational head and significant pressure changes prevent collisions.

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Only a longer-term study could determine if fish behavior might change in response to the turbine’s presence and create greater dangers.

A study with wider parameters would also reveal if impacts of the turbine such as stress or loss of equilibrium might expose them to greater predation.

A second HGE hydrokinetic turbine will be installed adjacent to the study turbine at the Mississippi Lock and Dam No. 2 Project. The study results suggest it will not introduce any greater risk. Because the fish survival in the study was ~100% and fish were not injured passing through the turbine blades, the second HGE hydrokinetic turbine should have little if any affect on entrained fish.

HGE would like to install "sets" of turbines... (click to enlarge)

Conclusions:
(1) Empirical study assumptions were valid, survival estimate precision was acceptable and results can therefore be assumed reliable.
(2) Small fish survival and large fish survival were 99%.
(3) No turbine blade passage injuries.
(4) Contact with the turbine and barge should not cause lethal injuries at the expected water velocities of 5.67 ft/sec to 9.68 ft/sec, well below the laboratory estimate of 20 ft/sec velocity necessary to cause harm.
(5) The HGE hydrokinetic turbine design protects fish from injuries in gaps at the turbine blade tip or hub and (because there is no operational head) from pressure related injuries.
(6) The HGE hydrokinetic turbine’s low number of runner blades (3) and a relatively large runner diameter (144 in) are characteristic of low impact turbines.
(7) Predation was not a factor at the HGE hydrokinetic turbine site. Predation activity was not directly observed, or indirectly assumed. The HGE hydrokinetic turbine minimized or eliminated factors that reduce a fish’s ability to avoid predators (e.g., stress, loss of equilibrium, pressure changes, severe turbulence, shear stress, cavitation).
(8) There was no evidence of danger from entrainment by the HGE hydrokinetic turbine and a second unit is not expected to change that.
(9) The species composition and size of fish in the natural environment is not precisely known but the very nearly 100% fish safety shown in the study results, encompassing a full range of fish sizes and types, indicate the HGE hydrokinetic turbine should have little if any affect on entrained fish.

This is a small but landmark moment in the birthing of the hydrokinetic energy industry. There is cause for celebration. And a lot more work to be done. Many say hydrokinetics are where the wind industry was in the 1980s.

But wave, tidal and current energies have many things going for them now that wind did not have back then, beginning with this good earth's urgent need for emissions-free, domestic and distributed sources of New Energy and ending with a populace that knows the score. In between, there are politicians who don't get it, but there is a ballot box for teaching them.

...and, eventually, long arrays of turbines. (click to enlarge)

QUOTES
- From the study’s conclusions: “Based on the results of this evaluation, the HGE hydrokinetic unit has little if any considerable impact on the fish populations in the vicinity of the Mississippi Lock and Dam No. 2 Hydroelectric Project.”