Continuing from our discussion previously, I will move on to talk about another energy resource; our oceans!
Ocean energy is derived from the use of seawater’s motive power, chemical and heat potential. Electricity can be generated from the ocean through the ocean’s current, tidal current and waves, and salinity and thermal gradients (Lewis et al. 2011)
As it is driven by renewable energy sources (waves, tides…), ocean energy is beneficial in reducing a reliance on our carbon-driven economy. If fully utilise, ocean waves is estimated to meet about 40% of the world’s demand for energy (Maehlum 2013)!!! At present, only tidal range technology is considered to be the commercially available and practicable form of harnessing ocean energy. Tidal range energy can be harnessed by building a dam/barrage across the entrance of an estuary (shown below).
During high tide, the sluice gates will open to fill up the estuary. Once the high water mark is reached, the gates will close. The gates will open up again when the tide recedes allowing the stored water to flow out. The flowing water will pass through the barrage’s turbines as it flows out, generating electricity in the process (Helston 2012).
A successful example is the La Rance Barrage in Brittany, France. It generates about 600GWh of electricity annually, sufficient to power a town of 300,000 people (Hamawii 2012).
While we have discussed a few alternative energy sources in a positive light, the vast limitations faced in their uses stem from the lack of a competent central grid system that can efficiently harness the energy contributions from the varied sources simultaneously. The video below exemplifies how such a grid system employed in the UK is coming to good effect:
The choice of energy alternatives, as we can see, offer a good variety for nations who are unable to utilise nuclear power at the present moment. Hopefully, with the use of these renewable sources (& an effective grid system), countries can advance towards a greener economy less reliant on conventional fossil fuel sources, ultimately building a cleaner environment for all to live in.
- Electrical and Mechanical Services Department n.d., How a tidal barrage works, Available from: <http://re.emsd.gov.hk/english/other/marine/marine_tech.html>. [01 April 2015].
- Hamawii, S 2012, La Rance Tidal Barrage, Tethys, Available from: <http://tethys.pnnl.gov/sites/default/files/sites/Annex%20IV%20Metadata%20-%20La%20Rance.pdf>. [01 April 2015].
- Helston, C 2012, Tidal, Available from: <http://www.energybc.ca/profiles/tidal.html>. [01 April 2015].
- Lewis, A, Estefen, S, Huckerby, J, Musial, W, Pontes, T, Torres-Martinez, J, Edenhofer, O, Pichs-Madruga, R, Sokona, Y, Seyboth, K, Matschoss, P, Kadner, S, Zwickel, T, Eickemeier, P, Hansen, G, Schlömer, S & von Stechow, C 2011, IPCC special report on renewable energy sources and climate change mitigation: Ocean energy, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
- Maehlum, MA 2013, How does ocean wave power work? Available from: <http://energyinformative.org/wave-energy>. [01 April 2015].