The revolutionary redox system that produces and stores energy in the home
Imagine having a fridge-sized box in your home that not only generates and stores electricity on-site, but heats and cools the house, provides hot water and even churns out oxygen and hydrogen to use or sell. That's the vision a team from the University of Newcastle and Australian company Infratech Industries is working towards, and New Atlas spoke to two of the minds behind this potentially game-changing "Swiss army knife" of energy production.
The team calls the device a Chemical Looping Energy-on-Demand System (CLES), and it's based on an original invention by Professor Behdad Moghtaderi of the University of Newcastle. Infratech, spearheaded by CEO Rajesh Nellore, has been involved almost from the start, helping out with the technical development of the system as well as plans to commercialize it.
An industrial-scale reference plant was unveiled in Newcastle, Australia in early April, designed for a hospital, retirement village or a similar-sized commercial building. The CLES wouldn't just supply the facility with electricity, but also help out with the heating, cooling and hot water, and produce oxygen and hydrogen that can either be used on-site or sold.
In short, the CLES acts like a combination of a generator and a battery: it can use natural gas to generate electricity to power a building, or take electrical energy from the grid or renewable sources and store it for later use. The system is based around a reduction-oxidation (redox) reaction, with a canister of a specially-blended particle mixture that cyclically gains and loses electrons. When those particles oxidize, they heat up, creating steam that drives a turbine to generate electricity. Then, when they reduce again, they release oxygen that can then be collected.
"Reduction is an endothermic process, so you basically consume energy to get it done, whereas oxidation is an exothermic process, you actually produce a lot of heat from the reaction," Moghtaderi tells us. "So by managing this cycle, we provide energy to the reduction step using an energy source, which could be natural gas, could be off-peak electricity, or could be electricity from renewables like solar or wind."
Along with power and oxygen, the excess heat that the CLES device produces can be captured and used to directly heat a building, provide hot water or, with the help of a separate attachment, be used for cooling. And to top it off, if needed the process can be tweaked to create harvestable hydrogen.
The particle mixture at the heart of the system is hidden behind a veil of IP secrecy, but the team says that the particles it contains are "naturally occurring," so they're readily available and reasonably cheap. The inventors say they buy them for under AUD150 (US$112) a ton, and only a small quantity of them are needed in a system at a time. They'll be packed inside a cartridge, designed to run through the redox cycles many times over. Cartridge changes will be a necessary evil, but each one is estimated to last between six months and two years, and the team assures us that refills will be priced competitively.
In earning its Swiss army knife title from its developers, the CLES can be run in two different modes. An energy storage mode works like a big battery where energy can be fed into the system from the grid or renewable sources like solar panels, and stored until it's needed. That could protect the building from outages, take advantage of lower off-peak electricity charges, or simply let its occupants store solar energy for night-time use.
"You could operate it like a typical energy storage system, which means during off-peak hours it would charge the particles, and the particles would discharge during the peak hours," explains Nellore. "So you get all the products, including electricity, oxygen, hot water, heating, cooling, during the day. It's the same principle as when you have solar power and a battery."
The second mode is what the team calls Energy on Demand. On this setting, the unit would be constantly fed energy from natural gas to keep the redox cycle running, generating enough power (along with the other outputs) to serve the building's needs. The main advantages of this mode is that it helps a facility reduce its reliance on the main grid and use natural gas instead, which is generally cheaper, more reliable and generates only about a third of the emissions.
"In distributed power generation, rather than having a massive centralized grid, you're talking about much smaller micro-grids," says Moghtaderi. "This system, in the Energy on Demand mode, has been designed for a micro-grid application. So essentially, if you deploy to a retirement village, and you hook it up to natural gas, that retirement village would be entirely independent of the national electricity network, and they can produce their own power and other utilities, 24/7."
In this mode, the CLES converts natural gas to electricity with an efficiency of about 45 percent. That's in the range (albeit towards the lower end) of efficiency ratings for industrial gas-powered turbines of this size. But, Moghtaderi says, that figure jumps to over 90 percent when you consider that the energy lost in the form of waste heat is being reclaimed, and the system is producing oxygen and hydrogen to boot.
In theory, not only could CLES save an organization or residence some money on their power bills, but savvy users could potentially sell off the oxygen and hydrogen by-products for an extra little income stream. And when the system is churning out an average of 120 kg (265 lb) of oxygen per day, that's going to build up.
But would the average person know how to break into the oxygen resale market? To simplify things a bit, the team has designed a unit that can store and pressurize the oxygen that the system produces into the same standard gas bottles that oxygen is regularly sold in. The researchers admit that this market and infrastructure hasn't really been developed yet, but they envision that eventually, with enough houses making excess oxygen, resellers might just pop around door-to-door to collect new stock.
"If this gets off the ground, in future the gas companies may not actually need a centralized facility to produce high-purity oxygen, they may rely on residential buildings to do that for them, and they just come and collect it," says Moghtaderi.
For regular use, small quantities of oxygen could be circulated through the building to freshen up the air inside. But, according to the creators, CLES produces far more oxygen than you'd be able to huff by yourself, so you're still going to have a surplus to sell. Or, in the case of a hospital or retirement village, canisters could be stored on site for use by patients and residents.
Hydrogen, by its nature, is much trickier. It's highly flammable and too dangerous for the average household to be producing and storing unchecked. But unlike oxygen, which the system produces constantly as part of its normal operation, the researchers say that the CLES will only create hydrogen when it's told to. For now, there probably isn't much need for the average household to produce their own hydrogen, but that might change in the near future, as cars powered by hydrogen fuel cells potentially become more widespread.
"Oxygen is a by-product, and it's a very valuable commodity," says Nellore. "But hydrogen would never be permissible in a residential or commercial environment. So it's only when you have fuel cell cars that need hydrogen, and you're trying to create a hydrogen infrastructure, then it would make a lot of sense to actually focus on the hydrogen by-product."
To demonstrate the CLES, the group has built a full-scale reference plant in Newcastle, Australia. About the size of a shipping container, this system is currently capable of producing about 720 kWh of juice per day, which according to the team is enough to power about 30 or 40 homes, a small hospital or retirement village, or a military field hospital. Making the system modular means that it could be scaled up to power bigger commercial buildings, but for now they're more focused on scaling down to serve individual homes.
"We're working on a miniaturized version for small residential applications," says Moghtaderi. "We're basically trying to compact everything that we've got, in terms of reactors, all the vessels, the moving machinery, everything, to the size of a small fridge. Then you can actually make use of the advantages of the system on an individual residential building."
Obviously one household won't chew through anywhere near as much power as a hospital or shopping center, so a residential unit will output about 24 kWh a day. Likewise, the budget to buy one won't stretch quite as far, and although the team is reluctant to put a number on the price tag just yet, they do say that it should be competitive with other home battery systems in both price and power.
"We believe that when we make the miniaturized version for individual houses, in terms of electrical performance, we would be as good, if not better, than Tesla systems," says Moghtaderi. "In terms of cost, our estimates show it will be about 75 percent of Tesla units."
Since the Tesla Powerwall currently goes for about US$6,000, we figure that puts the home edition of the CLES in the ballpark of about $4,500 – and the Powerwall isn't making oxygen on the side. Whatever they end up costing, the team is confident that the system will pay for itself within a year and a half.
Infratech and the University of Newcastle are planning to roll out the system, in its current larger scale form, during the second half of 2017. A demonstration of the CLES technology will be up and running in a dental hospital in Sydney around July or August, and if all goes to plan, commercial units of this size will be available for sale to similar-sized facilities by the end of the year.
Those looking to get their home off the grid will have to wait a little longer, though, with the miniaturized version about 18 months away. That said, the inventors have a rosy outlook for the future of localized energy production.
"Let's say you come home, you hook up your laptop and mobile phones to charge using your own power," says Moghtaderi. "At the same time, you recharge your hydrogen fuel cell car for the next day using the hydrogen that you yourself are generating. Meanwhile, you can inject some of the oxygen that you produce into the house and improve the freshness of the air, or alternatively you could just store it and sell it."
The system can be seen in action in the video below.