Riverine Hydrokinetic Technology: A Review

Student: Long Pham

Mar. 2014

CLASS REE516: ENERGY ENGINEERING II

•An emerging class of renewable energy that harnesses the kinetic energy of moving water

•Traditional hydroelectric requires large dams/reservoirs to create significantly high water head

•Hydrokinetic Technology can be installed in any rivers, streams, waterway with very low water head

What is it?

Sir Adam Beck Hydroelectric Generating Stations. Niagara Falls, Ontario, CanadaSource: Ontario Power Generation

Source: New Energy Inc. website: http://www.newenergycorp.ca

1,977 MW

• Water movements occurs naturally all over the planet: Ocean waves, tidal currents, rivers, streams, etc. The mid-west region of the United States alone has more than 6000 miles of rivers. Most of them remain untapped for electricity generation. Water movements are highly predictable and usually located right where we need them

• Hydrokinetic technology allows us to harness the energy from all kinds of water movements. Without building large dams / reservoirs that may alter the river systems, occupy the surrounding land and challenge the local wildlife.

• Add 13,000 MW of new generation capacity to the United State by 2025 (from EPRI [1])

Why it is so interesting?

Source: http://vdinh.weebly.com/unit-8-ecology.html

Source: New Energy Inc. website: http://www.newenergycorp.ca

• Single person portable, rapidly deployable electrical power generation for front line and disaster relief forces

• Able to generate 600W of continuous power over the widest range of operating conditions to power basic encampment equipment: computing devices, targeting systems, communication devices, etc.

• Can be setup in arrays to achieve power output 20kW,

• Bottom mounted to make it totally invisible. • A supplement to the U.S. Marines’ Ground

Renewable Expeditionary Energy System (GREENS) - a 300 W photovoltaic battery system.

Attractive Applications

Bourne Energy’s Militarized Backpack Power Plant. Source: Bourne Energy www.bourneenergy.com

Attractive Applications

Photo courtesy of D.Light Design Inc. (www.dlightdesign.com)

Attractive Applications

Sir Adam Beck Hydroelectric Generating Stations. Niagara Falls, Ontario, CanadaSource: Ontario Power Generation

The stations divert water from the Niagara and Welland Rivers above Niagara Falls which produce up to 1,997 MW capacity

Inspiration from: Integrated coal gasification combined-cycle technology (IGCC)“Install hydrokinetic turbines behind large dams to establish combine-cycle hydroelectric power systems to harvest additional power in the magnitude of MWs from the energy remaining in the water discharging from dams” [2]

• The theoretical limit for power coefficient Cp is for non-ducted turbines. (Betz limit)

• For ducted turbines:▫ Radkey and Hibbs (1981) reported ducted

Horizontal Axis Hydrokinetic Turbines can have power coefficient ranging from 0.66 to 1.69, well beyond Betz limit [4].

▫ Gaden (2007) used computational fluid dynamic simulation to study the effect of a duct to the flowing fluid [3]. He found that Betz limit could be surpassed by eight times!

▫ Mohammed et al. (2014) analyzed the duct effect on a horizontal axis hydrokinetic turbine using a Panel Method program. They found maximum Cp = 0.94 [5]

• Duct augmentation is an effective way to increase turbine’s efficiency.

Turbines’ ducted effect31

2capture p theory pP C P C Av

Duct effects on fluid flow a) Non-ducted, b) Ducted, c) Computational fluid dynamic simulation [11].

•Turbines suitable for these very low head applications are different from those used in conventional hydroelectric plants, like the Francis, propeller, Kaplan, or Pelton turbines

• In recent years, various concepts have been developed to harvest the energy of free-flowing water. However, methods employing a rotational turbine are more economically feasible for real-world deployments and commercialization.

•Similar to wind turbines, there are many different hydrokinetic turbine designs. They are broadly grouped into two categories based on the orientation of the axis of rotation

Classification of Hydrokinetic turbines

• Turbines having the rotational axis parallel or inclined to the flowing direction of water

• Feature rotors that resemble aircraft propellers• Lifting force • Advantages:

▫ Higher efficiency than cross flow turbines. ▫ No torque ripple, self-start capable

• Disadvantages:▫ Higher manufacturing and transportation cost

requirements for water sealed components the airfoil shape of the blades blade size usually big

▫ Disk shape of the rotor: Difficult for turbines to be stacked together In small, narrow rivers

Axial Flow Hydrokinetic Turbine

• Turbines having the rotational axis perpendicular to the incoming water current

• Two basic types of vertical axis turbine designs: based on Darrieus design (Fig. 6 a, b, c, d) and based on Savonius design (Fig. 6e).

• Darrieus: Lifting force; Savonius: dragging force• Advantages:

▫ Cylindrical rotor shape: Make use of space more efficiently Low cost duct augmentation Suitable for small, shallow rivers: diameter bigger than depth

which allows them to sweep a bigger area in shallow river streams, increasing the possible power production per turbine

▫ Lower manufacturing, transportation and maintenance: Don’t need expensive hydrofoil shape blades Smaller and simpler parts Generator can be placed from above the water surface with

direct connection to the rotor . • Drawbacks: Torque ripple, inability to self-start, and lower

efficiency

Cross Flow Hydrokinetic Turbine

• Hydrokinetic energy is highly predictable• Hydrokinetic resources are abundant, untapped, and located close to population• Hydrokinetic technology is environmental friendly• Same drawback as other renewable technologies: low efficiency

• In all of the hydrokinetic Research Development & Demonstrations (RD&D) found in the literature, the electrical and control design are simplistic and error prone, which significantly reduces the overall stability and efficiency of hydrokinetic turbines.

• A low cost, high efficiency, sensorless power electronics converter could be of significant interest to the emerging hydrokinetic technology, especially the small-scale deployments of this technology

Conclusion

Reference

Thank you!