Solar Panels Floating on Water Will Power Japan’s Homes

Solar Panels Floating on Water Will Power Japan’s Homes
More solar power plants are being built on water, but is this such a good idea?
By Bryan Lufkin, for National Geographic
PUBLISHED FRI JAN 16 12:07:00 EST 2015

Picture of a similar floating solar plant

Floating solar arrays take advantage of open water where land space is constrained.
Nowadays, bodies of water aren’t necessarily something to build around—they’re something to build on. They sport not just landfills and man-made beaches but also, in a nascent global trend, massive solar power plants.

Clean energy companies are turning to lakes, wetlands, ponds, and canals as building grounds for sunlight-slurping photovoltaic panels. So far, floating solar structures have been announced in, among other countries, the United Kingdom, Australia, India, and Italy.

The biggest floating plant, in terms of output, will soon be placed atop the reservoir of Japan’s Yamakura Dam in Chiba prefecture, just east of Tokyo. When completed in March 2016, it will cover 180,000 square meters, hold 50,000 photovoltaic solar panels, and power nearly 5,000 households. It will also offset nearly 8,000 tons of carbon dioxide emissions annually. (Since the EPA estimates a typical car releases 4.7 tons of CO2 annually, that’s about 1,700 cars’ worth of emissions.)

The Yamakura Dam project is a collaboration by Kyocera (a Kyoto-headquartered electronics manufacturer), Ciel et Terre (a French company that designs, finances, and operates photovoltaic installations), and Century Tokyo Leasing Corporation.

So, why build solar panels on water instead of just building them on land? Placing the panels on a lake or reservoir frees up surrounding land for agricultural use, conservation, or other development. With these benefits, though, come challenges. (See related story: “How Green Are Those Solar Panels, Really?”)

Solar Enters New Territory

“Overall, this is a very interesting idea. If successful, it will bring a huge impact,” says Yang Yang, a professor of engineering at the University of California, Los Angeles who specializes in photovoltaic solar panels. “However, I do have concerns of its safety against storms and other natural disasters, not to mention corrosion.”

Unlike a solar installation on the ground or mounted on a rooftop, floating solar energy plants present relatively new difficulties. For one thing, everything needs to be waterproofed, including the panels and wiring. Plus, a giant, artificial contraption can’t just be dropped into a local water supply without certain precautions, such as adherence to regulations on water quality—a relevant concern, particularly if the structure starts to weather away.

“That is one reason we chose Ciel et Terre’s floating platforms, which are 100 percent recyclable and made of high-density polyethylene that can withstand ultraviolet rays and corrosion,” says Ichiro Ikeda, general manager of Kyocera’s solar energy marketing division.

Another obstacle? Japan’s omnipresent threat of natural disasters. In addition to typhoons, the country is a global hot spot for earthquakes, landslides, and tidal waves.

Picture of a similar floating solar plant
The planned floating solar array for Japan would sit atop the Yamakura Dam, east of Tokyo.
To make sure the platforms could withstand the whims of Mother Nature, Ciel et Terre’s research and development team brought in the big guns: a wind tunnel at Onera, the French aerospace lab. The company’s patented Hydrelio system—those polyethylene “frames” that cradle the solar panels—was subjected to very high wind conditions that matched hurricane speeds. The system resisted winds of up to 118 miles per hour.

Why Japan Could Be the Perfect Spot

Given its weather, why build floating solar panels in the storm-filled, Ring of Fire-hugging Land of the Rising Sun? The reason: Many nations could benefit from floating solar power. And Japan is their poster child.

The largely mountainous archipelago of Japan suffers from a lack of usable land, meaning there’s less room for anything to be built, let alone a large-scale solar plant. However, the nation is rich in reservoirs, since it has a sprawling rice industry to irrigate, so more solar energy companies in Japan are favoring liquid over land for construction sites. Suddenly, inaccessible terrain becomes accessible.

Kyocera’s Ikeda says available land in Japan is especially hard to come by these days, as the number of ground-based solar plants in the country has skyrocketed in the past few years. (See related story: “Japan Solar Energy Soars, But Grid Needs to Catch Up.”)

But, he added, “the country has many reservoirs for agricultural and flood-control purposes. There is great potential in carrying out solar power generation on these water surfaces.”

In Japan’s case, Ciel et Terre says that the region’s frequent seismic fits aren’t cause for concern, either. In fact, they illustrate another benefit that floating solar panels have over their terrestrial counterparts, the company says.

“Earthquakes have no impacts on the floating photovoltaic system, which has no foundation and an adequate anchoring system that ensures its stability,” says Eva Pauly, international business manager at Ciel et Terre. “That’s a big advantage in a country like Japan.”

Solar’s Potential Ecological Impact

Floating solar panel manufacturers hope their creations replace more controversial energy sources.

“Japan needs new, independent, renewable energy sources after the Fukushima disaster,” says Pauly. “The country needs more independent sources of electricity after shutting down the nuclear power and relying heavily on imported liquid gas.”

This up-and-coming aquatic alternative impacts organisms living in the water, though. The structure stymies sunlight penetration, slowly making the water cooler and darker. This can halt algae growth, for example, which Ciel et Terre project manager Lise Mesnager says “could be either positive or negative.” If there’s too much algae in the water, the shadow-casting floating panels might be beneficial; if the water harbors endangered species, they could harm them.

“It is really important for the operator to have a good idea of what kind of species can be found in the water body,” Mesnager says.

Since companies must follow local environmental rules, these solar plants are usually in the center of the water, away from banks rich with flora and fauna. Plus, companies might prefer building in man-made reservoirs instead of natural ones, as the chances of harming the area’s biodiversity are smaller.
Could the Future Include Salt Water?

More than three-quarters of our planet is ocean, which might present alternative energy companies a blank canvas on which to dot more buoyant energy farms. But moving floating panels to the open sea is still in the future. Kyocera’s Ikeda says it would bring up a whole new realm of issues, from waves to changing water levels, which could lead to damage and disrupted operations.

Ciel et Terre is experimenting with salt water-friendly systems in Thailand, but ocean-based plants might be impractical, as offshore installations are costly, and it’s more logical to produce electricity closer to where it’ll be used.

For now, companies are aiming to build floating energy sources that conserve limited space, are cheaper than solar panels on terra firma, and are, above all, efficient. Ciel et Terre says that since its frames keep Kyocera’s solar panels cool, the floating plant could generate up to 20 percent more energy than a typical ground system does.

The Yamakura Dam project might be the world’s biggest floating solar plant, but it wasn’t the first-and it almost certainly won’t be the last.

The story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.
Comment on This Story

Energy From The Ocean

Ian Rosenblatt

CEO OceanFuels

At the Global Energy Conference,
Barcelona 2012

I am not a technologist, nor scientist, but an entrepreneur with a passion for imagination and innovation, and desire to find solutions to the ever growing problems we are encountering in the world today.

The ‘food versus fuels’ debate is familiar to most of us. It is widely recognized and reported that the demand for alternative fuels needs to be balanced by the problems associated with the supply of raw material feedstock.

Corn and sugar cane are two of the major feed-stocks for the bio-ethanol industry, but not only does large-scale production of corn and sugar damage the environment by the use of harmful pesticides, it uses another valuable resources: enormous quantities of water. For instance, it is estimated that the production of corn in the USA uses 135 billion US gallons of water a day.

Investment continues in other second generation biofuel resources such as Jatropha, Myscanthus Grasses, and Camelina, so called new energy crops. The argument being that they are grown on dry, arid lands that cannot sustain agricultural crop production for human consumption.

But with world population rising at an alarming rate, 7 billion forecast this year, 9bn by 2050 (as an aside a recent report indicated that the world will reach saturation point when we hit 15bn people) it’s inconceivable that further development in water recyling technology will not find a solution to turn these poor quality soils into land suitable for agricultural production.

In fact It was reported recently that a commercial airline is testing new jet fuel using Camelina as the raw material feedstock. Given that this only yields around 1,500 litres per hectare, and a Jumbo Jet uses a 49,000 litres for a one way trip across the Atlantic, how sustainable is that?

So I fail to comprehend the argument for using land resources in the long term as an alternative to meeting our fuel demands

Away from land based crops, we then have to consider the millions if not billions of dollars invested in an attempt to develop biofuels from algae grown in photo bioreactors. None of which to date have achieved any degree of commercial success

So the challenge is this:

  1. To find a feed-stock which is abundant and carbohydrate-rich. This crop needs to be sustainable, no-agricultural inputs (pesticides, fertiliser, land, water), and not be part of the human or animal food chain.
  2. To develop a biomass-to-ethanol conversion process that dramatically improves yields and has valuable by products that can reduce the cost of production per litre.

The answer is simple, use the Oceans,

They cover 70% of the World, they grow algae naturally. Indeed most of the oil we are getting out of the ground today comes from algae that lived millions of years ago.

Algae is the best source of oil we know.

Using algae from the Oceans is nothing new. Its been going on for generations its used in cosmetics, food, and many other related industries.

The question is how to ‘farm’ algae in the Ocean in a sustainable and economical way?

Ocean-Fuel have developed and patented an ocean-based cultivation system that can efficiently, cost effectively, and sustainably grow specific seaweeds varieties for conversion to ethanol, and deliver revenues per hectare far surpassing anything currently grown using land resources.Ocean Fuels cultivation system allows multiple seaweed species to be grown on specially designed growth platforms in the ocean.This platform enables the various species to achieve optimal growth at different times of the year therefore we have multiple harvests

As an alternative to land-based biomass, seaweed-based biomass is a sustainable crop which contributes to the environment in a positive way by sustaining or creating marine habitats, by increasing biodiversity, and by absorbing and removing nitrates and phosphates found in inshore waters.

One hectare of Ocean using the grid system will yield nearly 700 tons of wet seaweed, which dried gives us around 200 tons. On a like for like basis the average yield per hectare for corn is around 12 tonnes yielding 3,500 litres of ethanol versus 35,000 litres from macroalgae!

However the most important factor that must be taken into consideration is the value of the by products.

Around half of the 200 tons will be converted to biofuel, but the rest have a high value as fish oil, pigment, and minerals, with the jewel in the crown being pure protein which has a sales value around 10 times more than can be achieved from the sale of the biofuel.This gives us a financial model that allows the biofuels to be sold at competitive prices without the need for direct subsidies from the tax payer, and most importantly gives us the ability to make a competitive return on our investment.

So to summarise, we can be pretty certain that the world demand for energy will increase and that a significant portion of that demand for growth will be for energy transportation.

The question then, is can the planet support this?

What is our biomass potential and how do we optimize this?

Ocean Fuels vision enables that to happen.

Its low cost, low carbon, sustainable and scalable with ample biomass potential to enable biofuels to be a meaningful part of transport energy without impacting on the worlds need for food.

Cultivation & Yields

OceanFuel is the first company in the world to have developed a cost effective cultivation system, and their scientists have identified species of seaweed that photosynthesise high levels of carbohydrates. This makes the seaweed biomass suitable as substrate for microbial conversion into ethanol. OceanFuel’s cultivation system allows different species to grow on a specially designed ‘growth platform’ in the ocean.

This multi-level ‘column’ enables the different species of seaweed to achieve optimal growth at different times of the year, thereby allowing harvesting of raw material three or four times a year from the same platform. A mechanical ROV harvester has been developed for this purpose with Underwater Contractors Spain, SL a, Spanish Marine engineering company. This allows mechanical harvesting and pumping the seaweed biomass into a well-boat all operated from a boat without the need of divers.

On a like-for-like basis, cultivating one hectare of seaweed in the ocean using OceanFuel’s system will yield the equivalent amount of biomass as that of corn grown on 10+ hectares of land (see the table 1 opposite).

After 2 years of development Oceanfuel can extract the protein from the biomass with an amino acid profile equal or better than fish meal and 90% pure. We have agreements with several feed producers to sell this at fishmeal prices with the advantage of a fixed price.

After protein extraction, oil and pigments are removed and used for aquaculture in-feed solutions and or health food applications. Agreements are in place with fish and shrimp feed manufactures to buy this as an alternative to colorants and expensive oils.

The resulting carbohydrate slurry is further separated into a water-soluble fraction and a solids fraction.


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