Heat is energy, but often it is wasted. The noise, heat and vibrations created in a car’s engine are superfluous to its purpose – turning the wheels – but plenty of petrol is used up generating these useless by-products.
In a world where it’s a sin to waste energy, everyone is looking for ways to put all surplus resources to use. With solar energy the idea is to match excess daytime generation to massive hydrogen plants or pumped hydro sites, but there are plenty of industries with other types of energy to harness. What should they do?
That was the case for SA Water, which was using biogas produced at its Glenelg Wastewater Treatment Plant to power reciprocating engines on site but knew there had to be a way to get better value from something it couldn’t store and would never run out of.
Luckily the utility shares Adelaide with 1414 Degrees, an ASX-listed company developing a technology where energy is stored in molten silicon (which changes into liquid state at 1414°C). The company’s “thermal energy storage system” (TESS) had been tested using electricity, but could it take SA Water’s biogas? It was a challenge 1414 Degrees was willing to take, and in late April the tap was turned on to supply a pilot unit at the Glenelg facility.
So far so good, says 1414 Degrees executive chairman Dr Kevin Moriarty. “We can get an 85% conversion, so it’s better than what [SA Water’s engines] produce.”
SA Water saw it was getting good prices for its generated electricity but wanted to time-shift generation to be better aligned with peak pricing. “Our system allows them to do that,” Moriarty says. “It gives them much greater flexibility, rather than just burning gas in the engines as it’s produced and having no control over the price that they are selling the electricity at.”
Pilot programs are important when your technology involves molten rock. “We can’t prove this stuff in a workshop because you need to be supplying electricity and heat in an active commercial situation,” Moriarty says. “It’s too big a scale and we don’t have any heat use in our workshop.”
When 1414 Degrees took out its first patent more than 10 years ago the idea was for it to work a bit like a concentrated solar plant, where heliostat mirrors focus sunlight to heat a vat of silicon. Plans have changed a bit since then. “You don’t want to be pumping molten silicon around,” he says.
The emphasis shifted in 2012 to charging with electricity and recovering heat for industrial use and to generate electricity. “It means the silicon is sitting still – all it has to do is cycle through its molten state – which makes it vastly easier to manage.” Its other project, a 10MWh electrically charged TESS, was commissioned late last year and a second one is being built, “with a few improvements”.
Moriarty says some energy is lost through radiation, as a function of insulation, but most of the heat is available to be used. This means the unit can be charged and discharged at the same time, unlike more common forms of energy storage technology.
Things will really make sense, Moriarty says, when 1414 units are connected to the grid and are allowed to provide grid-stability services. The company wants to run a revenue-generating storage system at 10MWh, then scale that device up to 40MWh and then move into hundreds of megawatt-hours and into GWh territory. “This is not going to happen overnight, but we certainly can start to connect to the grid.”
The company is talking to a NSW-based retailer to help it service its renewables assets and is seeking heat-users in retailer’s local area. “There is twice as much energy use for heat as there is for electricity,” Moriarty says. “We haven’t had to do any marketing. We’ve had industries calling, and some of them are very big. They are all eager to free up gas and coal.”
Heat-users don’t have to worry about supplying energy onsite to heat the silicon, he says, as PPAs are so cheap that 1414 can locate wherever there are heat-users and provide grid security services. “It opens up multiple revenue streams for us,” he says. “If you’ve got a system like us you can do PPAs with solar or wind … and so you get vastly more flexibility.”
The gas at the site can’t be stored as it will degrade any type of storage tank, Moriarty says. “The gas isn’t clean at all; it comes with sulphuric acid and all sorts of nasties.”