April 2020: RayGen and NIRAS announce strategic alliance

NIRAS A/S (DK), NIRAS Australia Pty Ltd (NIRAS) and RayGen Resources Pty Ltd (RayGen) have recently formalised a strategic alliance that will include the delivery of a hot and cold Pit Thermal Energy Storage (PTES) solution for RayGen’s Solar Power Plant (‘solar hydro’) technology.

The first project of this alliance will be a fully dispatchable renewable energy facility delivering 4MW of solar generation and 3MW/50MWh (17 hours) of storage. RayGen is partnering with major Australian power utility AGL on the feasibility stage of the project. RayGen recently secured $3 million AUD funding from the Australian Renewable Energy Agency (ARENA) to advance the project to financial close in 2020. The project will be located in Carwarp, Australia. 

NIRAS has acquired significant expertise in the development of pit thermal energy storage (PTES) solutions and believes that PTES are poised to become a significant contributor to the worldwide energy market. NIRAS was recently the technical consultant for the successful Dronninglund SUNSTORE 3 Hot PTES, part of the Lunderbjerg District Heating System, Denmark. During summer months, solar collectors raise the temperature of water to about 90°C. A reservoir of 61,700m3 (lid area of 91m by 91m) stores the summer heat, so the district heating company can use it for supply during winter. The facility delivers half the thermal energy consumption used by 1,300 district heating customers in Dronninglund.

NIRAS has been engaged by RayGen to develop hot and cold PTES solutions as a key part of RayGen’s project. The nominal size of these pits is each 15,000m3 (about six Olympic swimming pools).

Thermal water storage is low cost, easy-to-site and non-toxic.

A recent report commissioned by ARENA [1] found a cost of storage of water as low as 0.05c/kWhthermal

● A recent study of Dronninglund PTES found 90 per cent thermal energy retention after seasonal storage (i.e. PTES systems retain 90 per cent of the thermal energy after three to six months when charged in summer and dispatched during winter) [2]

● RayGen estimates:

o  A PTES temperature difference of 90°C (thermal potential) has a similar recoverable electricity storage density to 1,000m head pumped hydro (gravitational potential)

o  10 hours of storage with PTES adds less than 5% to the total land area of utility solar farm

NIRAS Australia Managing Director Edward Lynch said: “NIRAS is excited to partner with RayGen on its ground-breaking Solar Power Plant technology project. We have delivered world-leading solar PTES integrations internationally and are excited to bring this capability to Australia. We are working closely with RayGen on this project, which we believe has the potential to accelerate the transition to renewable energy with low cost, easy-to-site water storage.”           

RayGen CEO Richard Payne said: “We are thrilled to announce our strategic alliance with NIRAS. NIRAS has proven their thermal water storage at scale across numerous projects larger than the RayGen Power Plant Carwarp.

“Water is the perfect storage medium.”


RayGen Resources is an Australian technology company with world-leading capability in the next generation of solar power and electricity storage. RayGen’s “Solar Power Plant” consists of RayGen’s proprietary PV Ultra (solar co-generation) and Thermal Hydro (electro-thermal storage) technologies. These technologies are designed in Melbourne and are protected by six patent families. RayGen has an experienced team of 30 staff in Melbourne and Bendigo, working across engineering, manufacturing, operations and commercial functions. In 2015, its first PV Ultra project started supplying power to farms near Bendigo in Victoria and has now been operating with high performance for five years. RayGen has built and sold 1MWAC (3MWco-generation) PV Ultra projects supported by power purchase agreements. RayGen develops and manufactures its high-efficiency solar modules at its 25MWAC manufacturing facility in Melbourne. For more information, please visit


NIRAS is an international, knowledge and engineering consultancy company with over 2,100 employees located in offices in Europe, Australia, Asia and Africa. NIRAS are actively implementing projects on every continent, providing integrated sustainable solutions to building, energy, renewables, utilities, environment and infrastructurethrough, process industry, infrastructure and planning, environment, life sciences and international aid.

For more information, please visit


Will Mosley

RayGen Resources


P: +61 3 8669 0380

[1] Australian Renewable Energy Agency and ITP (ARENA 2019) 2019, Renewable energy options for industrial process heat, published November 2019, accessed 6 January 2020,

[2] PlanEnergi and EUDP (PlanEnergi 2019) 2019, Best practice for implementation and operation of large scale borehole and Pit Heat Thermal Storages based on Danish experiences, accessed 9 January 2020

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