A range of federal initiatives are underway to support the full spectrum of hydropower generation in the US from conventional and pumped storage to marine and hydrokinetics as greater focus and resource is spent on renewables and energy security. The spectrum of possibilities is also wide ranging, from new to refurbishment, and from small hydro to R&D initiative support.

A major alignment of federal resources took place last year when a Memorandum of Understanding (MoU) to advance hydropower was signed by three national organisations – DoE, DoI (primarily through the Bureau of Reclamation – USBR) and The Department of the Army (via the Army Corps of Engineers – USACE).

Coming together to sign the MoU, in March 2010, the organisations aim to increase hydro production and reduce environmental impacts at their existing facilities. Small hydro development will be a prime focus for the effort, which will also see refurbishment and uprating of older equipment as well as first-time generation capacity at non-powered dams and constructed waterways.

The range of the MoU stretches from underpinning the common approach by more enhanced water resource management in the widest sense, including basin-scale assessments, to identifying specific federal facilities and land for initiatives to be undertaken, and provide for a push on R&D investment, such as advancing and promoting fish-friendly and low head turbines. Energy efficiency and sustainability are further important features in the MoU.

Funding rounds

In April, DoE and DoI announced US$26.6M in R&D funding for advanced conventional hydropower and pumped storage projects. Letters of intent were sought by May ahead of full applications to be submitted early this month. The funding is for projects over 3-4 years, and is the latest round in a series of R&D support programme in hydropower, which have until the latest have given more prominence to helping advancement of technology for marine, tidal and hydrokinetic opportunities.

This time, however, not only did pumped storage feature at all but it was given the biggest share of the pot, US$11.875M, albeit to assist R&D projects already in the pipeline. Submissions for projects tied with wind and/or solar, have significant economic value in dynamic grid support services and be able to start construction in 2014, will receive greater weighting in bid analysis. Grid storage and stability needs are recognised as having major importance as the push proceeds on support for arrays of clean energies and their variable outputs.

Energy Secretary Steven Chu said: “Deploying advanced hydropower, including using water to store energy, will help meet peak electricity demands and provide additional clean energy sources for America’s future.”

The latest funding pot had one other large share and it is devoted to supporting, specifically, low head small hydro. This focus is to assist the economic exploitation of hydro potential in existing federal systems, and is the focus of DoE. One of the smaller shares of the pot is aligned on the low head emphasis, and will see USBR undertake tests at non-powered sites.

However, the scale of the latest available funding does not cast a light on the size of the potential hydro resource that could be pursued at USBR’s own facilities alone, which it recently presented in a major report.

USBR

A year after the MoU was signed, the DoI released a report on the hydropower potential at 70 of USBR’s facilities that said an extra 1,008 GWh of electricity could be generated annually. In total, the sites have hydro power potential of approximately 226MW, and there is a wide spread of possible sizes and relative costs to develop.

Issued in March this year, the report described studying 530 sites in the west of the US, with the hydraulic structures ranging from dams and diversion conduits to canals and tunnels. However, the agency wouldn’t have the only possibility of undertaking developments at the potential hydro sites. There is potential for non-federal organisations to secure 40-year concessions to produce power.

In reporting its findings, the agency also released the Hydropower Assessment Tool that it employed for the analyses, which focused on basics of flow and head. It can be downloaded from USBR’s website, at www.usbr.gov/power.

The shortlist of sites were selected as offering the highest benefit-to-cost (B-C) ratio, allowing for federal and state ‘green’ incentives.

Sites

The sites with, by far, the largest hydro potential are:

• Sixth Water Flow Control in Utah, offering 25.8MW (114.4GWh) and a B-C ratio of a fraction over 3.0;

• Twin Buttes Dam in Texas, which could give 23.1MW (97.5GWh) on a B-C ratio of 2.61;

• Horseshoe Dam in Arizona, which offers 13.8MW (59.8GWh) at with a B-C ratio of almost 3.0;

• Pueblo Dam in Colorado, where the analysis suggests 13MW (55.6GWh) at with B-C ratio of 2.34; and,

• Upper Diamond Fork Flow Control Structure in Utah with 12.2MW (52.2GWh) on a B-C ratio of 2.36.

Many sites, though, are single digit megawatts or smaller, such as Soldier Creek Dam (444kW, 2.9GWh) in Utah, Vandalia Diversion Dam (326kW, 1.91GWh) in Montana, and Gila Gravity Main Canal Headworks (223kW, 1.55GWh) in Arizona.

The highest B-C ratio is 3.5, and is boasted by Bartlett Dam in Arizona, offering 7.5MW (36.88GWh). Other high ratios include 3.05 at Yellowtail Afterbay Dam, which could give 9.2MW (68.3GWh), almost 2.0 at Prosser Creek Dam in California, which could provide 872kW (3.8GWh), and 1.9 for Arthur R. Bowman Dam in Oregon, which could provide 3.3MW (18.3GWh).

Not all sites offer ratios greater than unity, however – 27 sites of the 70 have B-C ratios of less than 1.0, mainly in Colorado and Montana which also enjoy a number of positive ratio possibilities as the states have many potential sites in relation to others. The two states also have the sites with the lowest B-C ration offerings – 0.75 at St Mary Canal (Drop 5) in Montana, which offers 1.9MW (7.6GWh), and 0.79 at Paonia Dam in Colorado, which has potential for 1.6MW (5.8GWh).

States

In the USBR studies, the states offering the most hydro potential are:

• Utah – 53MW (220.2GWh) over seven sites;

• Colorado – 46.6MW (222.3GWh) over 20 sites;

• Montana – 33.3MW (168.1GWh) over 10 sites. The state has the best spread of hydro potential among projects, all but one being in the megawatt range, including Gibson Dam which offers 8.5MW (30.8GWh) on a B-C ratio of 1.32;

• Texas – one site (Twin Buttes Dam) with 23.1MW (97.5GWh), which alone keeps the state high in the state ranking;

• Arizona –22.7MW (103.6GWh) over four sites, including Horseshoe and Bartlett dams, and all with positive B-C ratios, even the smallest in the group, and on the list of 70 – Gila Gravity Main Canal Headworks;

• Washington – 15.6MW (54.4GWh) over six sites, three of which are below unity for the B-C ratio;

• Oregon – 11.9MW (48.3GWh) over six sites, the biggest site being nearly 4MW (15.6GWh) at Wickiup Dam although it and four others have B-C ratios below unity;

• New Mexico – 6.7MW (28.3GWh) over three sites, two of which are close to unity in the B-C ratio;

• California – five sites, almost all over unity for the B-C ratio but small, totalling 3.93MW (15.3GWh); and,

• Wyoming, Idaho, Nebraska, Nevada and South Dakota – between them there is less than 7MW over eight sites, and many close to unity for B-C ratios. almost 3.9MW (24.9GWh) over three sites.

Full spectrum hydro

There is scope and need across the board in hydro to gain useful support from federal organisations in support of national energy objectives.

While, in terms of scale, the total contribution from the likes of new or extra capacity at existing USBR sites will not tip the balance, projects at such sites would be part of a wider strategic undertaking.

At new sites, especially off the coasts for marine and tidal schemes, the projects are still in early stages of development overall and their R&D is running concurrently with them. So far, the plans for installed power are not significantly different from the federal exploitation of existing facilities onshore, but in the medium- to long-term it would be expected to far surpass. To get there, though, first needs federal lift.

However, potentially of wider importance for hydropower is the Government recognition of the benefit the sector can play to supporting the greater effort to develop other types of renewables, such as wind, and do so through pumped storage. It is that leverage which will help to significantly boost the share of the energy asset base of the US held by clean power resources.

Possibly, therefore, it can be anticipated that broad federal support for the hydro sector will continue, helping to squeeze more from presently tapped resources, exploit vast new potential off the coasts and pursue new pumped storage options to help support the grid. Without dynamic stability of the transmission network then the marginal benefits won from each extra megawatt of conventional and new hydro, and other clean energy resources, will not be fully delivered when built.