Battery Storage

Storing electricity is not an easy task, Moreover, electricity market structures work against storage economics. The cost of producing, storing and releasing electricity will always exceed the cost of producing and using it immediately. Market prices for electricity seldom compensate for the extra cost of storage, certainly not at the level of individual generating units. Even so, development of battery storage is all the rage. Flow batteries are touted as one of the cheapest ways to store electricity.

A high storage capacity at relatively low cost gives flow batteries a competitive edge, claim its backers. In a power system with weak connections where renewable energy is responsible for meeting most of demand, financially viable battery storage may eventually be needed, as well as for off-grid use, they explain.

Scientists from Aarhus University in Denmark have developed a new vanadium battery, which can scale power and capacity independently of each other. This means the battery can provide high power without being large and bulky. The combination could also be interesting for homeowners producing their own solar energy.

“Vanadium redox-flow batteries are not flammable as lithium-ion batteries and they are significantly more economic. They can also be recharged far more times than lithium-ion batteries—about ten thousand times without losing capacity,” states Anders Benthien at Aarhus University School of Engineering. The price is dropping, too, he adds and is now within reach of €200 per kW. Given that a typical household is served by 7 - 10 kW, the investment is in the region of €2000, he adds. Benthien expects the new battery’s return on investment to be less than ten years for a single homeowner with solar panels.

A Pinch of salt

A new Danish company called SaltPower wants to generate electricity through osmosis using geothermal water and other high salinity water sources. “Imagine a membrane only permeable by water but not salt. On one side you have saltwater, on the other side freshwater. The two waters will strive for equal measures of salinity, so the saltwater side will suck the fresh water through the membrane. The resulting osmotic pressure creates a flow that can generate electricity through turbines,” says Henrik Tækker Madsen, an assistant professor at Aalborg University and project manager at SaltPower.

SaltPower just opened its first pilot plant at a geothermal generation site in Sønderborg, Denmark. It will be testing the technology for a year. The company expects to add SaltPower to other geothermal heating facilities in Denmark and abroad. In this way it uses geothermal water for both heat and electricity. Jørgen Mads Clausen, chairman of Danfoss, an engineering company, was inspired by the concept that led to SaltPower after visiting a geothermal heating plant: “Here, the brine has a salinity of sixteen per cent. Seawater has around four per cent. A Norwegian company had tried using a similar osmosis technology with seawater [with a salt concentration of 3,5 %], but it wasn’t profitable. Due to the high salinity of the geothermal water I expected it to have a higher driving force but I am actually surprised by how much energy it generates. Unlike solar and wind power it never stops producing and there will be enough of this water for the next one thousand years,” he says. They expect a production price of around €0.012/kWh for a 1 MW facility, accessing geothermal water with 16% salinity.

Ocean tankers on methanol
Some 50,000 merchant ships carry over 90% of all international trade, most of them using bunker fuel to get around. The fuel is low on price but high on sulphur and other air pollutants. To meet increasingly stringent emissions regulations and hedge the risk of fuel price volatility, seven new ocean-going tankers will now be operating on methanol as an alternative to diesel. The vessels use a ME-LGI two-stroke dual-fuel engine developed by MAN Diesel & Turbo in Copenhagen. This first-of-its-kind engine can run on methanol, heavy fuel oil and marine diesel oil. Tests show that using methanol as a marine fuel reduces NOx emissions by 30%, SOx by 99.9% and particulates by more than 50% compared to diesel. It is the first time that tankers have been run on methanol. In 2015 Stena Line launched the world’s first methanol powered ferry, the Stena Germanica.

Satellite mapping the future

Rising sea levels usually take centre stage when mapping urban climate vulnerability. But flooding can also result from sinking land, an aspect often overlooked. This is about to change.

By combining satellite mapping of local land deformation with data about subsurface geology, sewerage, sea water level, groundwater table and precipitation patterns, it is now possible to predict changes much more precisely. A new study conducted in the Danish coastal town Thyborøn shows how this can be done and how it is possible to create a 3D-map that envisages risky areas. Knowing what might happen makes it possible to avoid the risk of sewage flowing the wrong way and it also helps local authorities and other stakeholders plan climate change adaptation decades in advance in both coastal and urban areas. Thyborøn is expected to subside by two to seven millimetres a year, which will increase the risk of flooding.

The study uses satellite data from the European Space Agency’s Sentinel Copernicus Services database to map the land deformation. The data is free and available to everybody.