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Site Selection for Low- and No-Head Hydroelectric Pilot Plants

By Andrew Provo
Nov 15, 2018

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According to the 2014 Oak Ridge National Laboratory study on untapped hydro-power potential, there is nearly 65 GW of untapped power in America’s waterways. The vast majority of this power remains undeveloped for many reasons, both environmental and commercial. One major impediment to the realization of this potential is the significant infrastructure required to install a conventional hydroelectric facility. The commercial and environmental cost of dam construction often makes the development of small-scale (50 kW–500 kW) hydroelectric installations untenable.

In order to tap the enormous potential of hydroelectric power available in America’s waterways, solutions with low initial and recurring costs must be developed. While Concepts NREC and others have developed systems that are functionally successful, it is of critical importance that the commercial viability of these systems be held in equal importance with their technical merit. It is these solutions that will allow for harnessing of this underutilized resource and add to the distributed nature of our power generation system. Common “water-to-wire” cost targets for installed plants are typically in the $2,000/kW to $2,500/kW range and of this value, the turbine-generator unit (TGU) cost is often only a fraction.

In order to understand the potential magnitude of the installation and facilities cost, we can look at the results of an International Renewable Energy Agency (IRENA) cost breakdown of traditional hydro-power projects.

  • Reservoir - 26%
  • Tunneling  - 14%
  • Power House - 14%
  • Equipment - 16%
  • Engineering - 7%
  • Owner Cost - 23%

As shown above, the equipment cost is only 16% of the overall project. While low/no-head hydro solutions can mitigate a number of these cost categories, it still illustrates how critical it is to factor in the effects of potential installation costs during the unit design. The best imaginable TGU design, from an engineering perspective, can easily fail, commercially, if these implementation costs are not carefully considered and addressed as early as possible in a program.

Additionally, one must consider the environmental and permitting impacts on the commercial viability of the system.  Often, full FERC permitting requires detailed and expensive ecological studies to be commissioned.  Therefore, in order to give a program the highest chances of success, one should look for potential test and installation opportunities that may avoid the costly infrastructure and commissioning costs.

In the case of prototype testing, it is recommended that units be tested at as close to full scale as possible in an existing test facility. There are many such facilities nationwide and the testing of a newly designed system in a closed environment with infrastructure provisions already in place will greatly reduce the monetary costs of valuable test data. Additionally, testing in a closed environment will also mitigate the PR cost of any issues surrounding the implementation of the prototype design, which can be equally important.

With testing complete, the program can then move to pilot installation sites. The ideal site will offer the lowest installation cost, while still validating the viability of the unit. Examples of two such sites that have been used successfully in the past are given below:

Waste Water Treatment Plants: Waste water treatment plants are attractive applications of low/no-head hydro-turbines because they offer fluid streams that are readily accessible without major investment, and relatively minor environmental permitting requirements. The New York State Energy Research and Development Authority (NYSERDA) funded the development of a hydro-turbine to extract energy from the effluent stream of a wastewater treatment plant. While this turbine was not determined to be ideal for the application, the treatment plan was shown to be a good proving ground for these technologies.

Electric Generating Stations: With thermal efficiencies of 30% to 50%, the amount of waste heat from these plants is staggering, and large volumes of water are needed for cooling.  Outflow from power-plants is attractive for low/no-head hydro-power applications because they also provide a low-cost source of water flow, and less demanding environmental permitting requirements. One study showed that the recovery of electricity from a European power-plant would be economical, even at very low electricity costs. Similarly, a system was installed at Samcheonpo power-plant in South Korea. And, the US Energy Efficiency Administration has identified 716 large power-plants that use “once through” cooling systems that offer good potential for low-head hydro-turbine applications.

By mitigating the test and installation costs of the prototype and pilot units, one can greatly increase the odds of creating a commercially successful product. Proving the viability of the technology, while avoiding a financial or public relations black eye, is key to securing the funding necessary to launch a no/low-head hydroelectric system at a commercial scale.

Tags: Turbines, Engineering

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