Tag Archives: Hydro

Energy Island and Other Ways to Store Energy with Water

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The latest issue of the IEEE’s Spectrum magazine contains a most interesting article:

“4 New Ways to Store Renewable Energy With Water”

The introduction outlines the problem:

In the United States, 97 percent of utility-scale storage in 2014 was in pumped-storage hydroelectric plants, according to research by Oak Ridge National Laboratory, in Tennessee.

In traditional pumped hydro, a dam separates a lower reservoir from an upper reservoir. When a utility company needs to store energy, the system pumps water from the bottom to the top. It generates electricity when water flows back down through a turbine. In 2015, Citibank estimated that the cost of power from pumped hydroelectric was about 5 percent of the cost of grid-scale battery-stored electricity. The problem is that there are many places that consume high amounts of power but don’t have geological opportunities to build conventional pumped-storage plants.

Now here at V2G UK we’re obviously of the opinion that the Li-ion batteries of a future electrified transport fleet are going to provide a lot of distributed energy storage. Alternative forms of energy storage are going to be needed too though, and the lower the cost of such storage the better! The IEEE goes on to consider four novel storage technologies that utilise water. A commodity of which we have plentiful supplies in and around the South West peninsula!

In a variation of the concept of a tidal lagoon being proposed over the Bristol Channel in Swansea is DNV’s “Energy Island“. Instead of relying on tides to fill the lagoon,:

For now, this energy island is only in the concept stage. DNV GL, based in Norway, is running a business case analysis with partners in the Netherlands and discussing plans to build a large-scale system.

In DNV GL’s energy island concept, a dike encloses a 10- by 6-kilometer section of the North Sea off the Dutch coast. To store electricity, the system pumps interior water up and out to sea. Letting water flow through a turbine on its way back generates electricity.

Unlike with traditional pumped storage, the inner lake can be built out in the sea as long as the seafloor has a sufficiently large layer of clay to prevent the ocean from seeping back in. There would also be some trade-off between more energy storage gained from a deeper ocean and increased construction cost.

Next an energy storage system that is undergoing trials – Stored Energy in the Sea (StEnSEA for short), which:

Is a hollow concrete sphere with a built-in pump turbine. It sits on the seafloor and, in its discharged state, is filled with water. To store energy, the system uses electricity to pump water out into the sea. When discharging, the pump works in reverse, generating electricity as water refills the sphere.

In November, Fraunhofer IWES installed a 3-meter-wide pilot sphere in southern Germany’s Lake Konstanz at a depth of around 100 meters. Following a year-long feasibility study, the team is now developing the concept for a 5-megawatt, 20-megawatt-hour full-scale system.

Next up is Canadian startup Hydrostor which aims to store compressed air in bags underwater:

Hydrostor’s system consists of weighted-down balloon like bags that are placed underwater and connected to a system on the shore. To store energy, it uses electricity to compress the air and fill the underwater bags. (A heat exchanger and underwater bath capture heat lost during compression to help preserve efficiency.) When electricity is needed, the air flows back out of the bag into a machine that expands it to drive a turbine. [See “Stashing Energy in Underwater Bags,” IEEE Spectrum, August 2014.]

Hydrostor commissioned a 660-kilowatt pilot plant with undisclosed storage capacity in November 2015 at Toronto Island, and the company is currently optimizing the performance. It could be followed by a 1-MW, 6-MWh storage system in Aruba later this year.

Finally there is the combination of a wind farm with built-in pumped hydro storage from Naturspeicher:

Wind turbines are built on the top of a hill with a pair of water storage reservoirs at their bases that raise them by an extra 40 meters above a typical turbine. A man-made lake sits at the bottom of the hill; energy is stored when the water is pumped up into the reservoirs, and electricity is produced when the water falls back down to the lake.

Naturspeicher plans to have a wind farm on line by the end of 2017 in the hills of the Swabian-Franconian Forest, in Germany, with pumped storage following by late 2018. It expects the system, when completed, to store 70 MWh and deliver up to 16 MW.

I wonder if any of these “low cost” energy storage systems will find their way over to South West England at some point in the not too distant future?

Renewable Energy is the Work of Generations of Engineers?

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Fresh from bemoaning the lack of grid-scale energy storage to support all the large scale solar PV parks currently being proposed here in not so sunny South West England, the latest edition of the IEEE Spectrum magazine landed on my doormat this morning.  In all the circumstances it would have been very handy if it had arrived this time last week, since it contains all sorts of statistics and arguments derived therefrom that support my position on that locally contentious issue!

In an article entitled “A Skeptic Looks at Alternative Energy” Vaclav Smil, a distinguished professor in the department of environment and geography at the University of Manitoba, bemoans (amongst other things) solar PV subsidies here in Northern Europe:

In June 2004 the editor of an energy journal called to ask me to comment on a just-announced plan to build the world’s largest photovoltaic electric generating plant. Where would it be, I asked—Arizona? Spain? North Africa? No, it was to be spread among three locations in rural Bavaria, southeast of Nuremberg.

I said there must be some mistake. I grew up not far from that place, just across the border with the Czech Republic, and I will never forget those seemingly endless days of summer spent inside while it rained incessantly. Bavaria is like Seattle in the United States or Sichuan province in China. You don’t want to put a solar plant in Bavaria, but that is exactly where the Germans put it. It happened for the best reason there is in politics: money. Welcome to the world of new renewable energies, where the subsidies rule—and consumers pay.

After laying his cards on the table at the outset Vaclav then lays into a wide range of renewable energy subsidies, making only two exceptions:

Without these subsidies, renewable energy plants other than hydroelectric and geothermal ones can’t yet compete with conventional generators. There are several reasons, starting with relatively low capacity factors—the most electricity a plant can actually produce divided by what it would produce if it could be run full time. The capacity factor of a typical nuclear power plant is more than 90 percent; for a coal-fired generating plant it’s about 65 to 70 percent. A photovoltaic installation can get close to 20 percent—in sunny Spain—and a wind turbine, well placed on dry land, from 25 to 30 percent. Put it offshore and it may even reach 40 percent. To convert to either of the latter two technologies, you must also figure in the need to string entirely new transmission lines to places where sun and wind abound, as well as the need to manage a more variable system load, due to the intermittent nature of the power.

I couldn’t have put it better myself, and I couldn’t have fitted it all into 5 minutes last Monday  either. If you have any interest in learning how to discern the difference between Green Energy and GreenWash I heartily recommend you read the article in full. Several times if necessary, until Vaclav’s message makes sense to you. To summarise, here’s his closing remark:

It is impossible to displace [the world’s fossil-fuel-based energy system] in a decade or two—or five, for that matter. Replacing it with an equally extensive and reliable alternative based on renewable energy flows is a task that will require decades of expensive commitment. It is the work of generations of engineers.

As if all that wasn’t enough, here’s a 45 minute video in which Bill Gates presents his views on energy policy in general, and Vaclav Smil in particular:

Finally here’s David MacKay’s “brilliant book” that Bill refers to around 18 minutes into his presentation. Sustainable energy, without the hot air.