The cost of energy is the number one issue impacting industry. Historically, the wholesale cost accounted for 33% of a company’s average energy bill. Yet with prices continuing to soar, it currently sits at around 50%, and could rise to as much as 66% in 2023. The impact of this is amplified as market volatility is equally pronounced. 

With the advent of intermittent renewable energy and the accompanying cost of balancing the grid, the energy network has become a significant part of production costs, with organisations keen to implement solutions which are more cost effective. 

Compressed air systems are commonplace throughout heavy industry, and are highly energy intensive, a fact which has been highlighted by a number of expert studies over the years. Indeed, you only need to look at figures produced by the Carbon Trust to realise the scale of the issue. According to their research, these systems consume around 10% of all industrial electrical consumption – around 8.8 TWh annually – resulting in CO2 emissions of 3.1 million tonnes a year.  

Meeting industrial challenges 

With industrial focus on the cost of energy intensifying, the deployment of ground-breaking technologies has been seen as vital to optimise the effectiveness of compressed air systems.

Having spent many years working within the compressed air industry we were all too aware of the energy, as well as decarbonisation, challenges being faced. Using our extensive experience in compressed air, thermal process and energy networks, we saw there was a real need for a cost effective and efficient means of storing energy at the point of use. Responding to this, we sought to come up with a solution that helped store energy cost-effectively and addressed decarbonisation using a world first technology. 

Alongside our partners, over the course of four years we developed the PRISMA Liquid Air Battery (Peak Reduction by Integrated Storage and Management of Air), a system that integrates industrial energy storage with industrial compressed air. This combination creates a unique new type of energy storage system, providing flexibility and reducing the cost of standard industrial processes. The result is a step change in the way industry consumes energy. 

PRISMA contains a high efficiency air compressor coupled with a unique air liquefaction and storage vessel that holds one hundred and fifty times the amount of energy as liquid air compared to existing compressed air storage. 

Storing cold energy 

At the heart of the system is advanced liquid and thermal storage technologies that store cold energy (or "coolth", as we like to call it,) and return it for later use. During charging, the PRISMA system is supplied with ambient temperature compressed air. This air is then chilled to -150C through the packed bed coolth store to the condensation point where liquefaction begins.

In a second vessel, this saturated air passes the "latent coolth store" which contains our unique phase change material (PCM) and there the air is fully liquefied and can be stored for long periods in a vacuum insulated tank. The PCM in PRISMA is a customised material (patent pending) that has a freezing point at cryogenic temperatures – less than -150C. When freezing, this material stores eighty times more thermal energy, or in the case of PRISMA – cooling, in the freezing process than a thermal fluid that doesn’t utilise phase change. 

When required, the whole cycle runs in reverse – the liquid air passes back through the latent coolth store where it picks up the stored heat removed from the charging process and becomes gas. It then passes back through the packed bed store where it again picks up stored heat to then discharge as usable ambient temperature compressed air.  

Energy transformation 

With industrial energy users often paid by suppliers and networks to flex their demand the ability to supply operations directly from the PRISMA system is highly beneficial. 

The whole system approach transforms energy hungry compressors into energy assets that can be operated to both run a factory, and to charge the PRISMA Liquid Air Battery. A fully charged PRISMA stores 2000kg of liquified air in its vacuum insulated air receiver that then provides compressed air to a factory enabling air compressors to be turned off during times of peak expensive electricity. A single PRISMA system can discharge 12m3/min of compressed air at 8barg for over two hours. 

The PRISMA Liquid Air Battery, coupled to a compressed air system, is comparable to a battery energy storage system as air compressors can be electrically sub-metered and baselined. The baselining of air compressor energy consumption through the sub-meter means that using more energy than the baseline (charging a PRISMA system) and turning off air compressors to use less energy (discharging a PRISMA system) can be measured at the meter and ‘traded’ by an energy supply company. 

This means that unlike other technologies that reduce a client’s bill through energy efficiency, PRISMA system actually generates revenue that is paid into the client’s account. Initial analysis show that the revenue generated by PRISMA is more than 20% of the cost of energy to run the compressors. 

PRISMA essentially becomes a battery that has no-limit to the number of times it cycles. To put this into perspective, a single system will cycle liquid air equivalent to 15 million kWh during its design life – or in the terms of the distance covered by an electric vehicle, a three-million-mile battery. 

Industrial benefits 

In applications, PRISMA’S whole system approach offers many advantages. Firstly, it offers a simple plug and play system that co-locates with an existing compressed air system. Not only does this mean it can sense when there is increased pressure in the air receiver, and therefore spare capacity, but it takes this excess to charge up, holding the compressors at full load efficiency and virtually eliminating wasted energy during part-loading. It can also provide backup capacity in the event of unplanned issues with the existing system. 

Secondly, in terms of air quality, the air discharged from PRISMA is ultra clean – far beyond the requirement of class 0 by nature of the compressed air having been liquified. Taking into consideration that ultra-dry air can sometimes be undesirable, a novel system has been put in place to partially re-humidify the air at the same time regenerating the desiccant used in the charging cycle.

The innovation doesn’t stop with the technology. Our commercial model incorporates a lease model where the revenue paid back to the customer by the energy company more than covers the cost of the equipment and the maintenance.  The only additional cost to the client is the site-specific requirements for installation.

With BEIS believing that a 'full roll out of this technology could have a big impact', implementing pioneering solutions is set to be the key to success for industrial users in the face of rising energy costs. 

Simon Branch is CEO at Innovatium

www.innovatium.co.uk

Tel: 0141 428 3953