Last Updated: Apr 2012
According to the International Maritime Organization's (IMO) second greenhouse gas study, renewable energy has the potential to reduce carbon dioxide (CO2) emissions from shipping by 1-10% per tonne-mile.
A ship's average annual fuel costs can be reduced by 10 to 35% by using a system such as the SkySails kite and on wind ships under optimal wind conditions, fuel consumption can temporarily be cut by up to 50%.
While the announcement that SkySails laid off a large part of its work force in February 2012 caused some concern, there continues to be interest in the technology.
In April, 2012, the University of Tokyo (UT) announced that it has designed a system of large, retractable sails measuring 64 feet wide by 164 feet high, which studies indicate can reduce annual fuel use on ships by up to 30%.
Initial wind tunnel tests on the wind engine indicated that the Greenwave Wind Engines are capable of providing at least 13% of the thrust required to propel a ship, saving 900 tonnes of fuel per year. The system can be retrofitted making them ideal for both new ships and the existing fleet.
The IMO reports that renewable energy is technically feasible only as a partial source of replacement power due to the variable intensity and the peake power of wind and sunlight. Solar and wind are intermittent energy sources, and therefore must be stored.
Kites have the advantage of not needing masts, they do not need a large area to store them and can be retrofitted to existing ships.
The greatest challenge for the US solar market according to the Solar Energy Industries Association (SEIA) is scaling up production and distribution of solar energy technology to drive the price down to be on par with traditional fossil fuel sources.
Current solar-cell technology would on average, only be sufficient to cover a fraction of the auxiliary power even if the complete deck area was covered by photovoltaic cells (ref: IMO).
The Skysails system works best on ships with an average speed no higher than 16 knots. Due to this speed restriction, only tankers (crude oil, product, chemical, LPG, LNG, other) and bulk carriers are being considered as potential users.
Current experience on board large vessels is limited but is growing, therefore modelling results are difficult to verify. Nevertheless, wind-assisted power appears to have potential for fuel-saving in the medium and long term.
A report released in February 2011, entitled The Energy Report by the WWF, found that all the energy we need could be provided from renewable sources by the year 2050. http://www.sustainableshipping.com/news/i100367/WWF_report_Global_renewable_energy_by_2050
Reports in June 2011 said that China will be leading the renewable industry drive. According to a report by Pew Charitable Trusts, in 2009 China dedicated approximately $34.6 billion to wind power, solar energy and other forms of renewable energy, nearly doubling America’s $18.6 billion.
In 2010, the Chinese government poured $120 billion into renewable energy while the US invested $20 billion, according to numbers cited at a Fortune panel.