Ocean Wave Energy

Reinier Eenkema van Dijk
December 7, 2016

Submitted as coursework for PH240, Stanford University, Fall 2016

Introduction

Fig. 1: Different Wave Energy Converter Concepts. (Source: Wikimedia Commons)

Ocean Waves are formed in areas where consistent breeze over the surface of the ocean, transfers energy through friction. The amount of energy contained in ocean waves, is enormous. The Electric Power Research Institute (EPRI) estimates that the total wave resource potential along the outer continental shelf is 2,640 TWh/yr (a breakdown of which can be seen in Table 1). [1] However, there are significant challenges associated with harnessing ocean wave energy that ensure that it is far behind other renewable energy sources.

Challenges

Building in the ocean is significantly more expensive than building on land. Saltwater is a naturally corrosive material that ensures materials degrade quicker, resulting in high maintenance expenses. [2]

Coastal Region	EPRI 2004 Estimate	Present Estimate Outer Shelf
West Coast (WA, OR, CA)	440 TWh/yr	590 TWh/yr (34% greater)
East Coast (ME through NC)	100 TWh/yr	200 TWh/yr (82% greater)
East Coast (SC through FL)	Not Estimated	40 TWh/yr
Gulf of Mexico	Not Estimated	80 TWh/yr
Hawaii	300 TWh/yr	130 TWh/yr (Not Comparable)
Puerto Rico	Not Estimated	30 TWh/yr
Total	2100 TWh/yr	2640 TWh/yr (26% greater)

Table 1:Wave Energy Potential Along the US Coast. [1]

Additionally, permitting for an ocean wave energy farm is much more difficult to obtain. Often there are adverse effects on marine wildlife that occur during the construction phase of the project. Depending on whether pile driving is necessary for the foundation of the wave energy converter, significant avoidance behavior can be induced in marine mammals as well as tissue damage in fish. [3]

Advantages

Besides the obvious renewable nature of wave farms, there are numerous advantages that may give it a leg up over other renewable resources.

Proximity - Many cities are located on ocean fronts, meaning that wave farms could be placed in close proximity to these cities, ensuring cheaper energy
Reliability - The consistency of wave energy is more ensures more reliable energy information than wind or solar.

Conclusion

Serious challenges still exist regarding the implementation of Ocean Wave Energy; major companies still disagree about the right implementation. According to Drew et al., "Over 1000 different wave energy conversion techniques have been patented in Japan, North America and Europe." [4] Some of the basic design implementations can be seen in Fig. 1.

© Reinier Eenkema van Dijk. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

References

[1] P. Jacobson, "Mapping and Assessment of United States Ocean Wave Energy Resource," Electric Power Research Institute, 1024637, December 2011.

[2] P. A. Lynn, Electricity from Wave and Tide: An Introduction to Marine Energy (Wiley, 2013).

[3] L. Bergström et al., "Effects of Offshore Wind Farms on Marine Wildlife - A Generalized Impact Assessment," Environ. Res. Lett. 9, 034012 (2014).

[4] B. Drew, A. R. Plummer, and M. N. Sahinkaya, "A Review of Wave Energy Converter Technology," J. Power Energy 223, 887 (2009).