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A PV, diesel, ESS hybrid case study: The DeGrussa solar project

by B Kiremire and M Bassingthwaighte, juwi Renewable Energies

This paper presents the diesel/solar/energy storage hybrid plant at the DeGrussa copper mine 900 km northeast

of Perth in Australia. The project history is presented, identifying key stakeholders, outlining the intent of the

project, and presenting the site to be supplied with renewable energy. An overview of the plant technical details

is then presented, followed by historical plant data illustrating the load following ability of the hybrid plant

despite variability in solar PV power, and load. Key project benefits include a reduction in diesel fuel

consumption, a reduction in plant emissions, and a diversification in the energy mix as a hedge against diesel

price volatility.

Juwi background

The juwi group was established in 1996 in Rhineland-Palatinate, Germany. The majority shareholder (63%) is a

Mannheim-based listed utility, MVV Energie AG. juwi has about 1000 employees located in offices on all continents.

Juwi’s core business is wind and solar project development as well as EPC and Operation and Maintenance services.

To date the juwi Group has completed wind projects totalling approximately 900 wind turbines with a total capacity of

2000 MW at more than 100 sites. In the solar PV segment, the juwi Group has designed and constructed more than

1,500 projects with a total capacity of around 2300 MW (with more than 100 utility scale projects). Combined, these

energy systems produce more than 7-billion kWh of clean energy per year, equalling the annual demand of around 2-

million households. In the process, the juwi Group has initiated an investment volume of around €7 billion to realize

these projects.

juwi Renewable Energies based in Cape Town, South Africa (“juwi”) is a wholly owned subsidiary of the juwi group

holding company. juwi has built and commissioned five solar plants totalling 121 MW under the renewable energy

independent power producer procurement (REIPPP) programme initiated by the South African government for utility-

scale renewable energy power generation. juwi has also been successful in developing and bidding wind projects under

the programme, and is also active in the government’s small IPP programme. In addition to this, juwi has started

constructing medium size PV projects (1 to 5 MW) that deliver cost competitive electricity to a range of commercial

and industrial end-users.

juwi South Africa has a large technically skilled and experienced team (50+ people) in South Africa. The team is

supported by the juwi head office in Wörrstadt, Germany. This ensures that all products have German engineering

mixed with local competency to ensure top quality product and delivery.

In this regards, juwi South Africa has recently built and commissioned the 86 MWp Mulilo Sonnedix Prieska PV Plant

in the Northern Cape, South Africa. The plant was commissioned in August 2016 and was delivered on time and on

budget. The plant employed 1740 people over the construction period, with the peak employment being 653. juwi

currently operates and maintains seven PV Plants in South Africa.

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Fig. 1: juwi operations world wide.

PROJECT BACKGROUND

The DeGrussa solar/diesel/energy storage hybrid plant is an off-grid plant that consists of 19 MW of diesel generation,

10,6 MWp of solar PV, and a 4 MW (6 MWp) 1,8 MWh energy storage system. The scope of the hybrid project was the

construction of the solar PV farm, the supply and installation of the energy storage system, and the configuration of a

control interface to allow the coordinated control of the solar PV farm, the energy storage system, and the existing

diesel generation plant.

Project structuring

juwi Renewable Energies approached Sandfire Resources in October 2013 to procure electricity from a 10,6 MWp

Solar PV facility which juwi proposed to install at the DeGrussa mine. juwi Renewable Energies developed the project,

and secured $20,9-million from the Australian Renewable Energy Agency (ARENA). In July 2015, at project financial

close, juwi transferred project ownership to a French renewable energy firm NEOEN who provided equity and secured

$15-million from the Clean Energy Finance Corporation (CEFC) (Sandfire Resources NL, 2016; NEOEN, 2016). juwi

Renewable Energies was responsible for the engineering procurement and construction works, and remains responsible

for the Operations and Maintenance of the plant. OTOC Limited was the surveying and infrastructure construction

company responsible for the construction of the plant (Sandfire Resources NL, 2016; juwi Renewable Energies

Australia, 2016; NEOEN, 2016). Kalgoorlie Power Systems (KPS), a wholly owned subsidiary of Pacific Energy

Limited is the power generation project developer and independent power producer responsible for the diesel power

station supplying power to the DeGrussa mine.

DeGrussa Mine

The DeGrussa copper mine, located 900 km north east of Perth, is the flagship mine of Sandfire Resources NL, a mid-

tier Australian mining and exploration company based in Perth (Sandfire Resources NL, 2016). The mine propelled

Sandfire from a junior exploration company to a leading mid-tier mining company in a three year period, beginning in

2009 with the discovery of the potential, through to 2012 upon completion of construction and commissioning of the

mine (Sandfire Resources NL, 2013; Sandfire Resources NL, 2016). The mine produced in excess of 68 000 tonnes of

contained copper and 37 000 ounces of contained gold in the 2016 financial year, and is reported to have a mineral

resource inventory of approximately 478 000 tonnes of contained copper and 625,000 ounces of contained gold with an

expected mine life of up to 2021 (Sandfire Resources NL, 2016). The mine has produced revenues in excess of $2-

billion since mining commenced in 2012, (Sandfire Resources NL, 2016).

The Sandfire leadership view the current environment of share market and commodity price volatility as an

environment in which innovation is the key to navigate the “rapidly changing sector” (Sandfire Resources NL, 2016).

Sandfire is an innovation ‘first-mover’ with the integration of a solar PV plant into its generation mix, to supply 20% of

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its energy requirements, reducing emissions by approximately 12 000 t CO2. Further they site the delivery of the project

as a ‘demonstration of the exciting opportunities emerging within the mining industry for the adoption of renewable

energy technologies at remote mine sites’ (Sandfire Resources NL, 2016).

Technical Details

Fig. 2: SLD of DeGrussa hybrid/diesel/PV/ESS plant.

The PV farm is located on a 20 hectare area adjacent to the DeGrussa mine (Sandfire Resources NL, 2016). The $40-

million project includes the hierarchical coordinated control of the diesel, solar PV and energy storage system, ensuring

the seamless integration of the different power systems (Sandfire Resources NL, 2016).

Over 34 000 solar PV modules were installed on a single-axis tracking system mounted on 4700 steel posts, and

connected to 10 x 1 MW PV inverters connected in pairs to 5 x 2,4 MVA, 0,4/12 kV transformers connected in series

via ring main units to the main plant distribution switchboard. The diesel plant comprises of 19 MW of diesel

generation capacity during normal operation, made up of multiple 1 MW and 2 MW diesel generators. The energy

storage system comprises of 4 MW maximum continuous rating ( MW peak), 1,8 MWh, high rate lithium ion batteries,

with power conversion and energy management systems. The total plant is sized to have an approximately 60%

instantaneous power penetration of installed PV compared to the load. The energy storage is used to provide power for

short durations of time so as to improve the load generation balance. The spinning reserve requirements to cover the

variations in PV power are covered by the energy storage, and diesel generators combined in such a way that batteries

respond more swiftly to deviations than the diesel generators.

The plant is controlled hierarchically, with primary controllers at each equipment level, and an overall advanced hybrid

controller overseeing the coordination of the different power systems. juwi developed an in-house SCADA system

suitable for the management of the overall hybrid plant, with data-archiving capability of up to 1 second resolution.

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Project benefits

It is projected that the project shall reduce carbon emissions by more than 12 000 t CO2/ year – a 15% reduction in

emissions based on the emission levels reported in the 2015 financial year (Clean Energy Finance Corporation, 2016),

supplying 20% of the mines energy requirements (Sandfire Resources NL, 2016) and reducing the cost of energy (Clean

Energy Finance Corporation, 2016). As stated by Oliver Yates, former CEO of the Clean Energy Finance Corporation,

“adding batteries to systems is increasingly making good economic sense” (Clean Energy Finance Corporation, 2016).

Plant performance

Fig. 3: Hybrid plant generation 2016-07-17.

Fig. 4: Hybrid plant generation 2017-06-26.

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Fig. 5: Hybrid plant generation 2017-06-27.

Fig. 6: Hybrid plant generation 2017-06-28.

The graphs above present the output of the combined plant compared to the site load. The trend of total hybrid

generation is the summation of the output of the PV plant, the energy storage system and the generators. The graphs

show that the total plant generation closely follows the site load, matching the load in conditions where there are large

variations in output PV power, and large deviations in load. The available generation capacity indicates the rated power

available based on the diesel generator units that are running. The plant is configured such that both the energy storage

system and the diesel generators provide frequency response reserve and spinning reserve but energy storage system is

configured to respond faster than the diesel generators.

As low load operation of diesel generators reduces efficiency, the key benefit of the energy storage system in this

hybrid configuration is the ability to switch off the diesel generators in the presence of high penetration solar PV,

reducing available generator capacity to levels significantly below the load, while ensuring the quality, reliability and

availability of supply.

Conclusion

The DeGrussa solar plant is a hybrid plant unique both in scale, and degree of solar PV penetration. As the cost of

energy storage decreases hybrid solutions such as these are becoming increasingly more viable. The implementation of

this plant demonstrates the coordinated control of solar PV, diesel generation, and energy storage systems for the

provision of reliable power, yielding cost reductions and diversifying the energy mix.

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References

[1] Australian Renewable Energy Agency. (2016, June 8). Mining success marks turning point for off-grid

renewables. Australia: ARENA Media Release.

[12] Clean Energy Finance Corporation. (2016, June 8). Remote power generation milestone marks turning point for

renewable energy. Clean Energy Finance Corporation Media Release.

[3] P Drager (2017, March 9). DeGrussa Solar Project knowledge sharing reports. Australia: Australian Renewable

Energy Agency.

[4] juwi Renewable Energies Australia. (2016, june 8). Largest off-grid solar project complete (DeGrussa mine).

Australia, Australia: juwi Press Release.

[5] NEOEN. (2016, January 28). Financing DeGrussa hybrid project Solar PV + Storage. Energy and Mines London

Summit. London: NEOEN.

[6] NEOEN. (2016, June 8). Neoen, owner of the DeGrussa 10.6MW Solar Station, the largest Australian off-grid

Hybrid power plant, announces project completion. Sydney: NEOEN Media Release.

[8] OTOC. (2016, June 8). Largest integrated off-grid solar and battery storage facility in Australia achieves full

generation capacity. Australia: OTOC Media Release.

[9] Pacific Energy Limited. (2016, June 8). Completion of largest hybrid solar/battery/diesel power station in

Australia. Pacific Energy.

[10] Sandfire Resources NL. (2013, August 4). Official Opening of DeGrussa Copper mine. ASX Media Release.

Perth, Australia: Sandfire Resources NL.

[11] Sandfire Resources NL (Director). (2016). DeGrussa Solar Project [Motion Picture].

[12] Sandfire Resources NL. (2016, June 8). DeGrussa Solar Project successfully commissioned - New $40M solar

power station in steady-state operations. ASX Media Release. West Perth, Australia: ASX Announcement.

[13] Sandfire Resources NL. (2016). Driving change and embracing innovation 2016 sustainability report. Perth:

Sandfire Resources NL.

[14] Sandfire Resources NL. (2016). Opportunity Redefined 2016 Annual Report. Perth: Sandfire Resources NL.

[15] L Vickery (2017, June 15). How can mining catalyse bold deployment of solar energy? DeGrussa Solar Project.

Eighth Plenary meeting of the policy dialogue on Natural Resource-based Development. Paris: Australian

Renewable Energy Agency.

Contact Greg Austin, juwi, Tel 021 831-6100, greg.austin@juwi.co.za