369
Power and Energy Directly from Water
energy. Stream-based hydrokinetic energy is not as much researched as wave energy,
although it is suggested that these resources can provide electricity needs of 23 million
homes [34–47,61–65] (Bertsch, 2012, pers. comm.; Dixon et al., 2008, pers. comm.). *,†
In lower southwest where wind energy has low potential, stream hydrokinetic energy
can be a very valuable resource. Waves and ocean currents can provide a continuous
power [34,61–65] (Bertsch, 2012, pers. comm.), which is not possible for solar, wind,
and tidal stream energy. ‡ Since the kinetic energy from a stream is proportional to the
cube of the speed of the current, site location is very important.
The hydrokinetic energy projects are renewable and emission free. The United States
can avoid emitting 250 million metric tons of carbon dioxide per year if hydrokinetic
energy represented 9% of the US energy consumption [34,61–65] (Bertsch, 2012, pers.
comm.). § Electric Power Research Institute (EPRI) estimates that hydrokinetic resources
can provide about 10% of today’s electric consumption in the United States [44] (Dixon
et al., 2008, pers. comm.). The sources of hydrokinetic energy are generally predictable and unaffected by weather variability. Wave patterns can be accurately forecast
several days in advance [34,61–65] (Bertsch, 2012, pers. comm.) and tides will always
reoccur every 12 h 25 min because they are connected to the moon’s gravitational pull
(Bertsch, 2012, pers. comm.). ¶ Both wave and tidal energy can provide base load power,
eliminating the needs for backup sources [34–65] (Bertsch, 2012, pers. comm.). **,†† River
currents, however, fluctuate seasonally and are susceptible to wet and dry years, and this
makes them difficult to predict from year to year [36].
13.3.2 hydrokineTiC verSuS hydroeleCTriC energy: PoTenTiAlS And iSSueS
Unlike hydroelectric energy projects, hydrokinetic energy projects have little or
no effects on the local aesthetics [36–40] (Bertsch, 2012, pers. comm.; Dixon
et al., 2008, pers. comm.). ‡‡ They are generally underwater or a little removed
* Hydrokinetic energy was included as an eligible renewable energy resource by the Energy Policy Act
of 2005. Various funding authorizations for research and development were also included in this Act as
well as the Energy Independence and Security Act of 2007.
† Bertsch, D.J., Juris Doctoral candidate, The University of South Dakota School of Law, 2011; Congress
defined hydrokinetic energy as “electrical energy from waves, tides, and currents in oceans, estuaries, and tidal areas; free flowing water in rivers, lakes, and streams, or man-made channels; and differentials in ocean temperature (ocean thermal energy conversion),” The Energy Independence and
Security Act of 2007, 42 USC §17211 (2006).
‡ Ibid.
§ Ibid.
¶ Ibid.
** Hydrokinetic energy was included as an eligible renewable energy resource by the Energy Policy Act
of 2005. Various funding authorizations for research and development were also included in this Act as
well as the Energy Independence and Security Act of 2007.
†† Bertsch, D.J., Juris Doctoral candidate, The University of South Dakota School of Law, 2011; Congress
defined hydrokinetic energy as “electrical energy from waves, tides, and currents in oceans, estuaries, and tidal areas; free flowing water in rivers, lakes, and streams, or man-made channels; and differentials in ocean temperature (ocean thermal energy conversion),” The Energy Independence and
Security Act of 2007, 42 USC §17211 (2006).
‡‡ Hydrokinetic energy was included as an eligible renewable energy resource by the Energy Policy Act
of 2005. Various funding authorizations for research and development were also included in this Act as
well as the Energy Independence and Security Act of 2007.