As in most engineering nowadays, attention is swinging from massive infrastructure to fixing the device itself. In water power, massive dams and tidal barrages are questioned because of their pollution such as methane from flooded vegetation and creation of a poisonous lake in one case, massive disruption to humans and wildlife and other issues. Tidal barrages produce very expensive electricity. Attention now turns to wave and tidal stream power using effectively no infrastructure - just devices attached to the sea or river floor or an existing jetty. David and Goliath.
It is popularly argued that tidal stream power is ahead of wave: some say by ten years. However, a new study by IDTechEx, Wave, Tidal and Hydro Power 1W-10MW 2018-2038 questions this. Of 28 projects examined, 18 were wave power. 3kW open tide devices are on sale for navigation buoys and powering subsea equipment. However, in wave power one supplier took a 10MW order and another claimed a 100MW order in the last few months alone. These are not for the superbly engineered 1-2MW giant "propellers" of tidal stream leaders. They are built of ordinary-looking 80-600kW units but there is a strength in addressing a wider power range from single units to those farms. Wave devices are beneficial as a tiny artificial reef or invisible to marine life and minimally dangerous to divers and subsea vehicles. Unlike the situation with open tidal power, some wave devices can replace diesel gensets and even tiny versions in lifejackets and floater lights have been designed.
Another megatrend is minimising and eliminating batteries as detailed in the IDTechEx report Battery Elimination in Electronics and Electrical Engineering 2018-2028. With open water power it is popularly taught that only tidal power is totally predictable with minimal intermittency but Seabased of Sweden, with the 100MW deal in Ghana and several lesser installations, claims that it has identified many places where waves are effectively continuous and no battery is needed. Its robust linear generator, the Seabased WEC S2.7, is designed to efficiently extract power from swell waves only 1-3 meters high, which are prevalent in the tropics. Their device makes good electricity in the smallest swell when wind turbines are still. Partly, it is due to seawater being over 800 times as dense as air.
Some argue that the cost of open tide electricity is less than that of wave electricity but neither is anywhere near the plummeting cost of solar electricity on land so beating it for mainstream electricity production in the next decade is a triumph of hope over reality. Creative marketing is the order of the day. With the right equipment such as boat-based tidal power and most wave power, you can beat diesel gensets in remote places suffering a whopping $1000/MWh. Diesel gets banned or severely restricted and having no fuel supply line from distant places is increasingly valued: look at the collapse in diesel car sales and the boom in electric cars.
Aquaculture is going offshore into the bigger waves and there is rapid proliferation of electricity-gobbling ocean floor mining robots, autonomous underwater vehicles, oil and gas subsea equipment and much more. Their operators do not compare with grid prices: there is no grid. Even on land, "grid defection" is becoming popular as users value the predictability, 100% zero emission and empowerment of their own electricity supplies. Almost all of the largest cities are on the sea or a large river. Bali, Indonesia chose Wello wave power from Finland largely because it is invisible, in stark contrast to wind and solar power unacceptable to tourists.
"The cost of energy generated with Wello Penguin is already very competitive compared to offshore wind energy, and in serial production we aim for a further 50% cost reduction", Heikki Paakkinen, CEO declares, "The potential market for the Wello Penguin in Indonesia alone is worth over a billion euros. However, the solution is viable globally on almost any ocean coast. Wello has also entered into a representation agreement for the Indonesian market with GEU which appraises Indonesia's ocean wave energy potential at more than 17 GW.
Wave power is often plug-and-play, it has deskilled service and repair, it can be used in deeper ocean, with common well-tested materials and it is easily integrated as a solution such as for mobile desalination. It is wrong to argue that it is behind open tidal power as it is first to commercialise in a big way.
Nonetheless, in Wave, Tidal and Hydro Power 1W-10MW 2018-2038, IDTechEx concludes that wave and tidal are largely addressing different markets. Raghu Das CEO of IDTechEx says,
"We find it very significant that some open tidal generators are made to capture strong near-surface tides, even river flow, and be rapidly redeployable and easily serviced. Creative marketing is more prevalent in tidal power now, with opportunities created with complete solutions such as the EC-OG module with battery, sensors, acoustic communications etc. dropped easily onto the sea floor as a unit and rapidly redeployed. There will certainly be billion dollar businesses appearing in tidal stream power too. The large units from Atlantis MeyGen and Scotrenewables in the UK are very impressive and they use less material than equivalent offshore wind units which are certainly not invisible. Expect baseload for much tidal and wave power in place of large banks of batteries for the chronic intermittency of wind and solar and their high material cost and maintenance when at sea. Competing with the malign effects of nuclear should not be too tough either. Indeed, nuclear is banned in a lot of countries now. Wind and wave power have been through a harrowing period of disillusion due to poor technology and engineering led projects but they are out of that. Now is the time to invest and indeed to use the rapidly expanding variety of devices coming onto the market."
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Top image source: Wello Oy, Wikimedia