Batteries may be getting plenty of attention in the mainstream media, what with Tesla’s Elon Musk and Atlassian’s Mike Cannon-Brookes tweeting each other in enthusiasm about South Australia’s plan for 100MW of storage, but that doesn’t mean the technology is mature.
The lifetime claims for many of the variations of chemistry used is untested, for a start, because the batteries haven’t been installed anywhere long enough, and the little problem of what to do with large residential and commercial batteries when they die attracts scant attention.
When the priority is to solve a problem as big as intermittency of renewable energy supply, and the solution is storage – and the clock’s ticking down to another hot summer – it’s not so much about picking a battery that will still look like the best technological solution in a decade or so. It’s about picking a battery that can be built in time and works out as good value.
“It’s a very significant problem,” says Robert Riebolge, chief network analyst of Adelaide-based energy storage company 1414 Degrees.
Riebolge (pictured) anticipates “quite huge” chemical storage installations are being designed to supply “fairly small” amounts of output. “When you think of having to supply gigawatts around the NEM you can imagine the consequences that will have,” he says.
He cites estimates of battery lifetimes of five years, 10 years, “we just don’t know what that cycle is, but we do know there will be a cycle of battery replacement and that … will start to create fairly significant environmental consequences in the next five to 10 years.
“Just think of these mountains of tyres from cars and the way in which they are disposed. These chemical batteries will be a worse problem than anything tyres will produce.”
Clear way forward
Storage is “quite clearly” the solution to the intermittency and the energy crisis Australia is facing, Riebolge says, but the way in which the market is constructed and the regulatory system is set up doesn’t really allow for its easy introduction.
The Australian Energy Market Commission, Australian Energy Market Operator and Clean Energy Regulator are all looking at rule changes that will facilitate the introduction of storage, and if these rule changes work as they are supposed to work it will open up the market for storage, he says. “And there is an opportunity for any type of storage to make a presence in the market.”
As for South Australia’s plan for a 100MW battery before the end of the year, Riebolge says it probably could work, depending on what sort of event one has in terms of peak demand, where there may be demand for load shedding. “If it’s only held back for that, then it could work.”
But given the intermittency of renewables and the share of generation they make up in South Australia it could well be that on a particular event day of peak demand there is no sun or wind, “and consequently 80MW wouldn’t go anywhere near trying to do away with a load-shedding event – especially, of course, if the interconnector with Victoria is non-operational or down for maintenance at that time.”
The retirement of coal-fired plants in South Australia and Hazelwood in Victoria have removed about 1,000MW of capacity from the market, he says, and small installations of 200-300MW are not going to solve that issue.
“To deal with that there has to be a transition period which may need some gas turbines of some description, but you’ll need a buildout of storage to be able to remove the entire intermittency of the installed capacity of wind and solar and then you need a buildout of wind and solar that can essentially meet the entire demand and meet the renewable energy targets that the particular regions of the NEM are looking at,” he says.
“It then becomes a question of what is the most economical and least environmentally damaging type of storage, and this is where our system really comes to the fore. It is an order of magnitude less costly than most other forms of storage currently available and it has no environmental consequences at all.”
Heat transfer
The solution Riebolge refers to is represented by 1414 Degrees’ single prototype of its patented thermal energy storage system (TESS), built in the Tonsley Park Innovation Precinct in Adelaide.
Inside the unit elements heat silica in receptacles to its melting point, 1414 degrees Celsius, where it has “a large energy capacity associated with every unit of silica,” he says. The elements require energy to become heated, of course, and renewables would fit the bill.
The heat energy is stored until demand requires it be turned into electricity via an energy recovery system such as a gas turbine or other type of turbine. With the silicon in molten state there is plenty of heat to go around, and it becomes a valuable by-product.
“You keep it at 1414 degrees and it has a latent store, which is a very significant amount of energy that silica stores at that molten latent phase, compared to other materials such as salt or any other material that has a latent heat characteristic,” Riebolge says. “You’ve got to keep it at that temperature to have the energy available for release when you need it.”
The silicon stays in the container for its 20-year lifecycle and decommissioning incurs no environmental cost.
The prototype has been running since September last year, with recoveries of almost 50% conversion of energy in to energy out. Riebolge says most energy recovery systems perform in the order of 30-35%.
“It’s significant value is that it provides a storage mechanism which has all the attributes of storage, like locational balancing, peak shaving, peak shifting, frequency control, voltage regulation, etc, etc, so it’s very important from that perspective. But the fundamental benefit of this type of storage is that it charges and discharges simultaneously, so it can be paired with any intermittent resource, such as wind or solar, or preferably a combination of wind, solar and biomass, and it converts that technology configuration from an intermittent resource to a load-following resource. It matches the demand profile almost exactly.”
The prototype is a 250kW energy recovery system with about a 1-2MWh storage coupled to it. A commercial demonstrator to be installed this year will be about a 10MWh thermal store coupled to an energy recovery system of about 2-4MW, which will fit inside a 40-foot shipping container.
Capacity can be added or reduced simply by adding or removing modules. “You size this according to the characteristics and demand profile of the particular customer you’re dealing with.”
The by-product of heat isn’t a problem, Riebolge says. There is enormous demand for it, particularly in industrial installations such as food processing and hydroponic farms, and it’s becoming more so because of the cost of gas, which it displaces. In the northern hemisphere, particularly Denmark, Scandinavia and the UK, the demand for heat extends to extensive district heating infrastructure. “And this just plugs straight into the district heating infrastructure and you’ve got an 80-90% recovery rate. Instead of burning fossil fuels for the heating infrastructure you simply take it from wind, solar, biomass or whatever other renewables are available at that site.”
If there is no demand for the heat, it can be used to generate electricity by using a secondary energy recovery system such as a gas turbine, steam turbine or jet engine. “Instead of using gas you would use the heat from the heat store, which would obtain its energy initially from a renewable source such as solar or wind. You turn a gas turbine which is powered by gas into a gas turbine which is powered by wind or solar, which is an exceedingly exciting development that we’re looking at closely now.”
If demand is for electricity only, units would be ideally placed close to substations. “In South Australia there are about 400 substations. If you place one of these devices in each one of those substations you’ve essentially solved the intermittency problem.”
Over the past 10 years 1414 Degrees has invested more than $3 million with the assistance of AusIndustry grants. For five years it has funded research by the University of Adelaide engineering faculty into silicon energy capture and recovery.
Cat in the bag
The 250kW prototype isn’t big enough to test the efficiency of channelling the heat into a 50-80MW gas turbine, and Riebolge suggests a trial may have to wait for TESS systems around 200-300MW.
There are plans to float the business in the middle of the year with the ambition to raise about $10 million to spend on a commercial demonstration unit – a 10MWh thermal installation coupled to a 3-4MW turbine. “That will give us some very, very good data as to the commerciality of the system.”
The company did not put in an expression of interest for the South Australian battery tender, he says, because it was not prepared to disclose intellectual property. In fact the company is so secretive about its hot little powerhouse it wouldn’t even supply a photograph of the prototype to EcoGeneration.
Other than an efficient storage system the future of energy supply relies on adoption of a smart grid, where devices communicate in the cloud with generation so that demand is matched to supply in real time. “That technology is there now,” Riebolge says. “What is missing, of course, is the regulatory framework and market mechanisms to allow that to happen.”
With some smart planning, the transition from legacy networks to smart networks should be relatively painless. 1414 Degrees is ready, he says, armed with proprietary electronics that calculate when to dispatch electricity based on weather forecasting data. Schneider provided electronics for the prototype and is working with the company on the commercial demonstrators.
“We would want to keep quite a tight lead on the IP of course, so we’d in the first instance probably construct these devices under our own supervision, so that would be in Australia.”