Electricity from Wave and Tide: An Introduction to Marine Energy
Paul A. Lynn
Format: PDF / Kindle (mobi) / ePub
A concise yet technically authoritative overview of modern marine energy devices with the goal of sustainable electricity generation
With 165 full-colour illustrations and photographs of devices at an advanced stage, the book provides inspiring case studies of today’s most promising marine energy devices and developments, including full-scale grid-connected prototypes tested in sea conditions. It also covers the European Marine Energy Centre (EMEC) in Orkney, Scotland, where many of the devices are assessed.
- global resources – drawing energy from the World’s waves and tides
- history of wave and tidal stream systems
- theoretical background to modern developments
- conversion of marine energy into grid electricity
- modern wave energy converters and tidal stream energy converters
This book is aimed at a wide readership including professionals, policy makers and employees in the energy sector needing an introduction to marine energy. Its descriptive style and technical level will also appeal to students of renewable energy, and the growing number of people who wish to understand how marine devices can contribute to carbon-free electricity generation in the 21st century.
with a wide variety of machines, some stranger than others; in the case of tides, with tidal mills and barrages and, more recently, turbines that tap the kinetic energy of tidal streams. In this chapter we introduce the physics of ocean waves and tidal streams as a prelude to explaining the principles underlying some of today’s most promising developments. 2.1 Ocean waves 2.1.1 Linear waves The theory of linear waves, often referred to as Airy waves, was originally devised by the English
pitching occurs whenever the ﬂoat length equals an integral number of wavelengths: l = N λ, N = 1, 2, 3 (2.12) Figure 2.16c shows a pure heaving condition with one and a half wavelengths occurring within the device length, giving an ‘extra’ crest. There is now a net vertical force, but no tendency to pitch. In general, heaving occurs whenever the ﬂoat length is much smaller than a wavelength (in which case it effectively ‘samples’ the height of each passing wave), or when it equals an odd
the hydrofoil, fairly near the hub, as shown in Figure 2.37. The stream ﬂows horizontally from left to right and, viewed from the stream direction, the rotor is turning clockwise. Clearly, in this view the blade has a very different orientation from that of an aircraft wing in level ﬂight, and this can be confusing. So let us start by emphasising that, viewed from the stream direction, the blade presents its 5 Hub 8 Stream direction α 1 Rotation 3 6 2 4 Figure 2.37 Flow speeds and forces
that at Billia Croo, and the data continuously available via EMEC’s centralised SCADA system. The provision of robust and reliable cabling, rated to transmit the power generated by megawatt devices, is a major requirement at both test sites. Cable-laying may sound straightforward, but in practice it involves heavy equipment and considerable expertise, especially in Orkney’s challenging conditions. Figures 2.49, 2.50 and 2.51 give some idea of the scale of operations. On reaching shore, the 11 kV
energy available to tidal devices. Interactions with wildlife. Acoustic noise from tidal devices may adversely affect certain species of sea mammals, ﬁsh and diving seabirds, so it is important to measure a site’s background noise, establishing a baseline for comparison with device-generated noise. Obtaining accurate measurements can be challenging in areas of high tidal ﬂow, since there is a lot of noise associated with water ﬂowing past measuring equipment, which can artiﬁcially add to the