Blog

Wastewater Treatment: Turning waste to clean energy

Posted on June 5th, 2019 in News

1414 Degrees’ Thermal Energy Storage Solution (TESS) takes electrical or gas energy, stores it as latent heat in molten silicon at 1414°C and discharges it as both heat and electricity on demand, in the proportions required by consumers.

SA Water approached 1414 Degrees to develop a TESS with gas, rather than electrical input, to store energy from their wastewater treatment biogas. From here an exciting new chapter in Australia’s renewable energy story began. This is the first technology in the world to solve the issue of effectively storing biogas as thermal energy to produce heat and electricity on demand.

As the first wastewater treatment plant to use this unique thermal energy storage system, SA Water will help to showcase the GAS-TESS’ significant environmental and financial benefits.

What is biogas – and why does it matter?

Biogas is produced when organic waste, including human waste, agriculture waste, manure, plant material or food processing waste, is broken down in an anaerobic (oxygen free) environment with the help of bacteria. The process is energy-efficient and environmentally friendly; the outcome is highly versatile biogas that can be used instead of conventional fuels for heat and power, and even for running vehicles.

Globally, biogas is an increasingly important source of energy. Germany is a pioneer in this area, due to the large number of agricultural biogas plants on farms. In Germany, more than 8,000 plants produced 7.4million TOE (tonnes of oil equivalent) of biogas in 2014. In that same year, the US produced 6.3million TOE and China 7.8million TOE – whilst in contrast, Australia produced just over 300,000 TOE[1].

This seems to be a missed opportunity for Australia. We have significant agriculture and food processing industries, producing organic waste from factories, livestock farms (particularly dairies), wineries, grain and vegetable producers and the potential to generate significant quantities of biogas. Meanwhile, natural gas is in short supply and can be subject to high spot price surges.

Biogas is a highly economical source of renewable energy, and it is also a fantastic source of heat. Given up to 50% of EU annual energy consumption is for heating, naturally occurring biogas has the potential to reduce the demand of fossils fuels and hence reduce emissions. Even in Australia we use more energy for heat (primarily for industrial processing) than electricity.

The fact is around 27% of Australia’s total energy use was for electricity in 2014-15. This compares with 33.5% for heating and 39.4% for transportation – partly due to the vast distances our trucking industry handles.

Time-shifting energy use

 So, why has biogas received so little attention to date? One of the biggest issues has been storing the gas so it must be used as it’s generated.

This is one of the challenges SA Water were facing when they approached 1414 Degrees about using the TESS storage to help them time-shift their energy use.

Currently, they must use their biogas as it is produced, which is not necessarily when it is most advantageous for them to do so. Before being burnt the gas must be scrubbed to reduce wear and tear on the engines. Heat is also an integral part of the sewerage digestion process.

What wastewater treatment plants want is a stable, consistent source of heat, less maintenance and electricity when it’s needed – not simply when it’s produced – and that’s where 1414 Degrees’ GAS-TESS comes in. It burns the biogas and stores the energy – so it doesn’t need to be flared and wasted or immediately used in gas engines to generate electricity.

Because TESS has a high level of combustion, it’s also easier to manage biogas toxins – the residue that typically creates maintenance issues with generators. SA Water won’t need to ‘scrub’ the gas, saving significant time and operational costs.

Other energy storage technologies, such as batteries or pumped hydro, could store the electrical energy generated from the reciprocating engines, but not also produce the heat energy SA Water needs. Along with the GAS-TESS being low cost, the use of abundant, cheap, compact and energy dense, silicon allows large amounts of energy to be stored. 10MWh of storage is contained in a space roughly the size of a 40 foot shipping container.

This is the type of solution many other Australian industries need as well. In 2012-13, around 70% of the energy used by Australia’s manufacturing was natural gas used to produce thermal energy[2]. From district heating to food processing, and any type of production and manufacturing, every process uses electricity or burns fossil fuels like natural gas and liquified petroleum gas (LPG) to make heat.

With 1414 Degrees’ GAS-TESS, SA Water will be able to store its biogas as latent heat in molten silicon at 1414° Celsius, providing maximum energy efficiency. This heat can then pass through an energy recovery system, converting it into heat and electricity on demand.

Wastewater treatment as a clean, efficient energy solution

 SA Water is trialling 1414 Degrees’ technology to time-shift the combustion of biogas to help it meet a target of zero net cost energy from 2020 – which will lead to significant cost savings.

The data produced from this project will help better quantify the potential of biogas as a reliable and stable source of energy, and thermal energy storage’s ability to make renewables more cost-effective across many different industrial applications.

Ultimately, it will also allow for the vast sources of biowaste to be used in a more productive and sustainable way.

To watch the full site construction and learn more about the journey so far visit:

https://1414degrees.com.au/gas-tess-videos/