Magnificent Tidal Energy Project To Double As New City Park – CleanTechnica

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Tidal energy is a massive, virtually infinite clean power resource just sitting out there, waiting to be tapped. The wait has been a long one, partly because the most efficient tidal energy systems involve expensive new infrastructure. If only someone could figure out a way to combine tidal energy with some other useful infrastructure to help defray the cost, like a new pedestrian and cycling bridge over a river, or a flood control system. Oh, wait…

A Slow Start For Tidal Energy

Tidal energy leverages the natural, steady, constant motion of ocean tides to generate electricity. The International Renewable Energy Agency estimates that the global amount of technically recoverable, zero emission electricity from tidal motion could add up to 1,000 gigawatts, and that’s just counting locations near coastlines.

Compared to wind and solar energy, though, tidal energy has been slow out of the box. Part of the industry is focused on tidal energy devices that can be be tethered in place to harvest clean kilowatts without the need for extensive infrastructure. These devices have to overcome some stiff challenges, including corrosion risks, durability, and power take-off issues, but some are closing in on market-ability (see lots more CleanTechnica tide-power coverage here).

On the other end of the scale are “barrage” tidal energy systems that funnel water through turbines situated in a dam or dam-like structure. These are considered to be more efficient than tethered devices, but the infrastructure factor can involve significant changes to landscapes and habitats.

That helps to explain why barrage systems are so rare today. The concept dates back to the 1920s, but the only barrage system to go into operation in the 20th century is located at the La Rance Power Station in France. It was constructed as a retrofit to an existing dam.

The Sihwa Lake Tidal Energy Case Study

The 21st century is off to a slow start as well. The only other tidal energy barrage in operation is the Sihwa Lake Tidal Power Station in Korea. It went into operation in 2011 and it is also a retrofit to an existing facility. However, this project is particularly interesting because the facility in question was already serving multiple purposes, and the International Hydropower Association has spotted an opportunity to promote similar projects elsewhere.

“Sihwa Lake is a 43.8 km² artificial lake constructed as a land reclamation project by the South Korean government in 1994, using a 12.7 km long seawall at Gyeonggi Bay,” the IHA explained in a 2016 case study.  “It was created to provide reclaimed land for the nearby metropolitan area, flood mitigation, and secure irrigation water by converting the costal (sic) reservoir to fresh water.”

IHA notes that the tidal energy facility has resolved a serious water quality issue that bedeviled the lake. “In 1998, the chemical oxygen level in Sihwa Lake was 17ppm, but has since been reduced to 2ppm, resulting in an improved habitat for all species of fish,” they observe.

“This site has become a very popular site for learning about lively ecosystems, with over 146 bird species including stork and mallard, and some 23 million birds living in and around the lake,” IHA reports.

Korea & Liverpool Collaborate On Tidal Energy

The IHA anticipated that success of Sihwa Lake would lead to similar projects in Korea. So far that has failed to materialize, but urban planners over at Liverpool City Region in the UK caught wind of the idea. They are running with the ball. Assisting in the effort is the developer of the Sihwa Lake project, the Korean firm K-Water.

Last year, Liverpool Mayor Steve Rotheram and K-Water Vice President Jeong Kyeongyun signed a Memorandum of Agreement to push the new Mersey Tidal Power Project off the drawing board and into the waters of the River Mersey, with K-Water providing insights and lessons learned from the Sihwa Lake project.

If you’re wondering why Liverpool, that’s a good question. BBC News cites Dr Judith Wolf, of the National Oceanography Centre, who notes that the city’s high tidal range makes it good location for harvesting tidal energy efficiently.

“We can predict how the energy will come from the ocean to the River Mersey for a long time into the future,” Wolf also told BBC News.

Make That A Magnificent Tidal Energy Project

The signing of the MOU followed a two-year technical assessment period, and Liverpool is not letting the grass grow under its feet. Last week the city announced that formal planning for the Mersey Tidal Power project has begun. They also released a series of renderings that envision the project as a beautiful new green space linking communities in Liverpool and the Wirral peninsula with a new route over the river, limited to cycling and walking.

In addition to the transportation and recreation angles, Liverpool is also promoting the project as a hedge against climate-related flooding.

“It opens the possibility of a first-ever cycling and pedestrian route over the river between Liverpool and Wirral and could also provide a defence against future flooding risks associated with climate change,” the city explained in a press statement.

“A barrage could also help manage long-term environment issues related to climate change, including managing the effects of sea level rise on the Mersey,” they emphasized.

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Tidal Energy Is Coming For Your Fossil Fuels…

The big question, of course, is who will pay for a massive new urban infrastructure project. Liverpool Mayor Rotheram is not shy about putting the hard sell on the UK government for a financial assist.

“Beyond the banks of the River Mersey, this is a national infrastructure asset that could position the UK as a global leader in the renewables race and help to turbocharge our net zero ambitions,” he said.

…And Your Nukes, Too

The public planning part of the process kicks off on March 15. There are years to go before approvals are issued and the financing is in place, but it already looks like momentum is building for additional projects in the UK.

Last year, New Civil Engineer took a deep dive into the topic of tide power in the UK. They listed seven tidal barrage and lagoon proposals in the works for the west coast of the UK in addition to the Liverpool project: Swansea Bay Lagoon, Wyre Barrage, Mostyn Docks, Severn Barrage, West Somerset Lagoon, North Wales Lagoon and Morecambe Bay and Duddon Estuary Barrage.

“If all were constructed, they would have a combined capacity of around 20GW,” noted NCE reporter Rob Hakimian.

That sounds like competition with nuclear energy is brewing. In that regard, Hakimian draws out the difference between tidal stream and tidal range projects. Tidal stream devices are designed for smaller-scale electricity generation. They simply run on the hydrokinetic energy of an ambient current.

In contrast, tidal range projects, like that proposed for Liverpool, deploy hydropower turbines that run on pressure built up in a barrage or lagoon. They can scale up to a level comparable to nuclear power plants.

Hakimian cites Cardiff University professor and consultant Roger Falconer, who underscores the potential for tidal energy to make nuclear power plants irrelevant in England, outperforming them on cost, construction time, lifespan, acreage required to build, and of course, waste disposal issues.

“Falconer points out the other advantages of tidal over nuclear,” Hakimian emphasizes. “You don’t have the legacy of hundreds of years of nuclear waste to dispose of in a container in an underground cofferdam. And it will protect the coast from floods and sea level rise. And in some cases you could have a road on top.”

Hakimian’s article sparked a lively discussion by NCE readers. If you have anything to add, drop us a note in the CleanTechnica comment thread.

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Image: A new tidal energy project would harness the power of tidal range in the River Mersey, link riverside communities in Liverpool and the Wirral Peninsula, and serve as a climate change management system, too (courtesy of Liverpool City Region).