Raising the game

20 June 2008



Houston, Texas-based Hydro Green Energy (HGE) is one of a growing number of players in the field of hydrokinetic power production in the US . IWP&DC discovers more about the company’s plans to convert non-hydro dams into low impact hydro facilities


Hydro Green Energy (HGE) is a power project developer and equipment manufacturer that designs, builds and operates hydrokinetic energy systems. The company presently holds four preliminary permits from the Federal Energy Regulatory Commission (FERC) for the conversion of non-hydro dams into low impact, conventional hydro power facilities. These are located in the US state of Mississippi, where Hydro Green’s Chairman and CEO, Wayne F Krouse, was born and raised.

HGE has three years to assess the projects under its permits, and the company’s hydrokinetic power equipment will be deployed downstream from the hydro facilities. All four projects are owned and operated by the US Army Corps of Engineers and cover the functions of flood control, fish and wildlife enhancement, augmentation of low flow, water quality control and recreation. The project sites are:

• Mississippi 1: Located at the existing Sardis dam at Sardis Lake on the Tallahatchie River. Sardis dam is approximately 80km south of Memphis, Tennessee. The dam has an average height of 30m and is 66 years old. The lake covers approximately 398km2.

• Mississippi 2: Located at the existing 20m high Enid dam at Enid Lake on the Yacona tributary of the Tallahatchie River.

• Mississippi 3: At the existing Grenada dam at Grenada Lake about 16km from Grenada, Mississippi in Grenada County on the Yaloshuba River. Grenada dam is approximately 160km south of Memphis, Tennessee.

• Mississippi 5: The project site is located at the existing Arkabutla dam on the Yazoo River. Arkabutla dam is approximately 32km south of Memphis, Tennessee.

The initial project feasibility studies have been completed for the Mississippi dams and HGE will soon begin to design the power generating facilities. By the end of 2008, the company must submit a Notice of Intent to FERC, which is a declaration that it intends to develop the hydro power project.

While the company is presently considering a number of ways to extract power from the non-hydro dams, the initial feasibility studies have shown that three of the four projects for which it has permits are economic and worth pursuing. The facilities will be eligible to receive the federal Section 45 renewable energy production tax credit (PTC) of 1cent/kW.

Total generation from the three projects is expected to be approximately 40MW, with capacity factors at each facility in the 50-60% range. HGE is in early stage discussions with potential power buyers and hopes to have the Mississippi projects built and operating by December 2011.

Heart of the development

In April 2008, HGE closed in Series-A funding with a US$2.6M investment from the Quercus trust, a prominent US investor in the renewable energy sector. It hopes to secure its Series-B funding by the end of 2008. This would allow the company to grow its project portfolio and build a manufacturing facility in the US.

HGE’s technology platform operates in rivers, tidal areas and oceans. Its equipment (called Hydro+) can also be deployed at existing hydro power projects which bolsters the electrical output of the existing scheme using a cutting-edge, environmentally-friendly technology. The company holds a US patent (6,955,049) and international patents in over 40 countries on its core technology. Twenty-one additional hydrokinetic patents are pending in the US and internationally.

At the heart of the HGE hydrokinetic turbine, which is a dual ducted horizontal axis unit, is a turbine assembly with three blades spinning to extract kinetic energy from the water’s flow. To improve efficiency a shroud is added around the turbine blades with a diffuser. The shroud reduces loss of energy and improves turbine efficiency, while the diffuser also acts to increase available power and improve efficiency of the turbine. These both improve the flow dynamics and allow for efficiencies greater than those for the Betz coefficient.

The innovative turbine design was developed by Krouse and fine tuned by Concepts NREC, a US based turbomachinery design firm with experience of developing the US Department of Energy’s advanced, fish-friendly hydro power turbine in the late 1990s. HGE claims it is the most efficient and highest power producing hydrokinetic turbine unit in the industry. Water to wire efficiency is calculated at 70% for the c second generation design, the HKA, which significantly exceeds the Betz Limit of 59%.

A NASA-sponsored fluid dynamics study found in 2006 that HGE’s patented turbine design (the first generation unit) will produce at least 240% more power than pinwheel based turbines, which are presently deployed by other hydrokinetic developers. This finding was independently confirmed in 2007 by both Concepts NREC and Hatch Energy, an international energy engineering and consulting firm with over 80 years of experience in the hydro power industry.

First Hydro+ project

HGE is currently moving forward on a path to power generation in September 2008 at its first Hydro+ project in Hastings, Minnesota. The 3.6m diameter hydrokinetic turbine being fabricated for the Hastings project has a coefficient performance of 0.60 at 2m/sec, which stays relatively constant over the nominal operating range of the turbine. The Hastings turbine is capable of extracting 38kW of power at a river flow rate of roughly 2m/sec. With increased velocities, the same unit can produce as much as 300kW.

HGE says that installation of its Hydro+ projects is relatively straightforward. The issue requiring the most thought and discussion during the Hastings design was over how best to secure the hydrokinetic units in the tailrace with anchors and tethers.

Much thought and discussion also took place over a nine-month period for the stakeholder consultations necessary for the licence application for the Minnesota facility. The City of Hastings and HGE conducted a three-stage consultation process with several federal and state agencies. HGE believes this will result in a licence application that FERC will approve in a timely fashion.

Extensive data will be gathered on fish survivability and water quality once the units are installed at Hastings. Even though baseline samples collected to date did not show any zebra mussel invasion in the project area, HGE and the City of Hastings assembled a zebra mussel control plan. All environmental data will be made public and be reviewed by the stakeholders to determine whether additional consultations need to take place after the units have been in operation. This is as agreed via the adaptive management approach to licensing that was taken by Hastings and HGE. If any unexpected impacts occur, the City and Hydro Green Energy can shut down its project in a matter of minutes and would then work with stakeholders to identify problems and implement timely solutions within days.

Tidal interests

In terms of its hydrokinetic power plans, HGE is primarily focused on river projects at this point in time, both Hydro+ projects and run-of-river hydrokinetic projects where the company’s equipment will be installed and operated without any existing hydro power facilities near the hydrokinetic units. Plans are underway for small and large projects in Alaska, Mississippi, Louisiana and New York. Hydro Green Energy is also in pursuit of a number of international projects.

In addition, from data the company has reviewed so far, the tidal projects it is pursuing are located in waters with excellent energy potential. Preparations are underway to study these sites in greater detail this summer with subcontractors.

The turbine to be deployed in the tidal setting will be a modified version of the model presently fabricated for river projects. The modification, which is under development, will allow for the asymmetrical ducted unit to pivot so that it fully captures all tidal flows at maximum operational efficiency.

For more information, please contact Hydro Green Energy on tel: +1 877 556 6566, email: [email protected] or visit www.hgenergy.com



Hydro Green Energy's response to FERC's white paper on pilot hydrokinetic licensing

Hydro Green Energy fully applauds FERC for its interest in hydrokinetic technologies and for the creative and thoughtful policy work it has done to date to advance the hydrokinetic power industry. FERC has shown leadership and a real commitment to seeing that projects are placed in the water sooner, rather than later, while at the same time ensuring that much thought is given to environmental issues.
Unfortunately, some federal resource agencies have not shared FERC’s enthusiasm for new technologies, as well as FERC’s understanding that hydrokinetic technologies hold much promise as a new source of clean energy that can play a key role in reducing climate change and improve quality of life. These agencies possess the ability to diminish FERC’s efforts to temporarily shorten the licensing process for hydrokinetic technologies while more data is gathered. We hope these agencies will play a thoughtful and creative role as the industry moves forward.
Hydro Green Energy will utilise the pilot licensing process on a number of its projects and believes that the pilot process will serve as an important stepping stone for it to advance proposed projects. We believe the pilot process will at some point in time outlive its usefulness, but when that time comes, it will be appropriate to either create an entirely new licensing process solely for hydrokinetic technologies or to largely exempt the hydrokinetic technologies from the current conventional hydro power licensing process. Creating that new process or adopting an exemption will be much easier to accomplish, we believe, because of what will be learned by all stakeholders through their various pilot licensing experiences.



Hastings dam Hastings dam
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