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268 Renewable Energy Devices and Systems with Simulations in MATLAB and ANSYS ®
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and market structure to focus on the large potential of MHK to also contribute to the pool of renew-
able energy generation.
This chapter covers the broad spectrum of MHK generation. The state-of-the-art power take-off meth-
ods is discussed. The types of electrical generators and the options for implementation are presented.

11.1 INTRODUCTION
Marine and hydrokinetic (MHK) renewable energy has gained great interest in recent years because
of its potential to provide a significant contribution to the electricity supply around the world. For
example, studies have shown that the United States has a large theoretical MHK energy resource from
the movements of tides, ocean and river currents, and waves; the total magnitude of the theoretical
MHK resource is on the order of U.S. electricity demand (Figure 11.1). In particular, the U.S. West
Coast, Hawaii, and Alaska have wave resources that are among the strongest. The magnitudes and
locations of the MHK energy resources given based on a series of resource assessment studies [3–7]
are plotted in Figure 11.1, and the total available resource from different types of MHK technologies
is listed in Table 11.1. Note that the wave resource data were collected for a water depth of 200 m, and
the 2012 U.S. electricity generation was estimated at 4054 TW-h/year [1, 2].

The ocean wave, ocean current, tidal current, and
river current resource in the United States
(terawatt-hours per year [TW-h/year])

590 1146*
8 240
21

80 200
<1
1570 130
416
FIGURE 11.1 The theoretical MHK resources in the United States. (Courtesy of NREL, Denver, CO.)

TABLE 11.1
Total Available Resources and Equivalent Percentages
of U.S. Electricity Generation in 2012
Total Resource Equivalent % of
(TW-h/Year) 2012 Generation
Ocean wave (blue) 2640 65
Ocean current (red) 200 5
Tidal current (green) 445 11
River current 1381 34