An Evaluation of the U.S. Department of Energy's Marine and Hydrokinetic Resource Assessments (2013) / Chapter Skim
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1 Introduction
1 Introduction
Pages 13-26
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From page 13... ...
; as of December 2012, FERC had issued 4 licenses and 84 preliminary permits while an additional 42 projects are in the pre-filing stage for a license.1 Though permit activity is not a reliable predictor of the future development of MHK resources because developers apply for permits before completing project plans and financing, it does indicate increased interest in MHK resource development. However, most of these permits are for developments along the Mississippi River, and the actual deployment of all MHK resources is extremely small.
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From page 14... ...
of the potential MHK resource are based on limited, possibly inaccurate data and assumptions related to the total resource and the fraction that might prove extractable. DOE contracted with five assessment groups to conduct separate estimates of the extractable energy from five categories of MHK resources: waves, tidal currents, ocean currents, marine temperature gradients (also known as ocean thermal energy conversion [OTEC]
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A CONCEPTUAL FRAMEWORK FOR MHK RESOURCE ASSESSMENT The nation's MHK community currently lacks a well-defined, consistent resource terminology. The committee observed that each of the assessment groups employed different terminology to describe similar results.
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In order to develop its approach to the SOT and to review individual resource assessments within a single context, the committee created a conceptual framework (Figure 1-1) of the overall MHK resource assessment.
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This allowed the committee and those who read its reports to visualize the processes used to develop the assessment results requested by DOE. This framework establishes three terms -- the theoretical resource, technical resource, and practical resource -- to clarify the overall resource assessment process as described by each assessment group and to allow for a comparison of different methods, terminology, and processes among the five assessment groups.
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From page 18... ...
Tides, ocean currents, and riverine/in-stream 2 Current power Power of horizontal currents flowing through a W/m Horizontal kinetic energy density vertical plane of unit area. flux (power density)
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From page 19... ...
; ΔT, temperature difference between warm and cold water for OTEC plant (°C) ; PL, pipe loss/fractional energy loss to cold water pumping (~0.2-0.3)
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In particular, for tidal currents, ocean currents, and marine thermal gradients, the theoretical resource cannot be estimated without taking into account the far-field back effect. Here, the back effect refers to the reduced potential of the resource due to feedbacks from the presence of a device or device array.
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From page 21... ...
During presentations from DOE and the assessment groups and ensuing discussion with the committee, it became clear that each group offers a different interpretation of what types of constraints would need to be included among its extraction filters. However, it is clear to the committee that estimating the technical resource from the theoretical resource requires filters that represent the general physical and technological constraints associated with energy-extraction devices.
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From page 22... ...
BOX 1-2 The Theoretical, Technical, and Practical Resource MHK resource assessments are going to be of interest to a variety of par ties, including electric utilities, project developers, and public officials. However, the orders-of-magnitude differences between theoretical, technical, and practical resources need to be stressed, especially because some resource assessments have been publicized in terms of a national or regional single-number estimate.
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From page 23... ...
After discussion with both DOE and the assessment groups, the committee concluded that the groups had interpreted "maximum practicably extractable energy" to mean the technical resource and that DOE did not expect the assessment effort to incorporate site-specific information needed to quantify the practical resource. While a determination of the practical resource is beyond the scope of the tasks assigned by DOE, the committee sees the constraints represented by the socioeconomic and environmental filters as being among the most important considerations influencing future MHK investments.
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From page 24... ...
Although such estimates provide a broad order-of-magnitude idea of potential energy resources, many extraction filters are needed to determine the technical resource, and at this time the assessment groups can rigorously evaluate only a few of these filters. Most of the extraction filters require assumptions about which particular MHK technologies will be used and what their technical specifications will be; moreover, the technologies are likely to vary by resource and location -- for instance, wave energy off the coast of Oregon
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From page 25... ...
, others are currently hosted on platforms operated by individual assessment groups. Given that one of DOE's objectives is to compare the various MHK resources with one another and with other renewable energy resources, the lack of coordination and consistency between the assessment groups was counterproductive.
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From page 26... ...
For this report, the committee reviewed final assessment reports for the waves, tides, and OTEC assessment groups and a July 2012 draft final report from the iverine assessment group.6 No final report was available for review from r the ocean currents resource assessment group; its report is expected to be complete by June 2013. Instead, the committee based its evaluation on presentations from and discussions with the assessment group.
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