Combined data center and solar power station for Canberra

A study commissioned by the ACT Government and ActewAGL has found that a large-scale solar power plant is feasible in Canberra: "Solar Power Plant Pre-feasibility Study". If re-elected, the government will seek expressions of interest to build the plant. As suggested to the Chinese government in 2003, I propose the plant be built on the roofs of new data centres and warehouses in industrial parks. This will allow the land under the plant to be put to use, provide power for the data center and industrial buildings. It would also overcome environmental problems with the previously proposed data centre for Canberra.

Building Design

The complex would use a standard industrial building design, with a roof strengthened to hold the solar collectors. Most buildings would be initially used as low cost warehouses and only fited out as data centers when required. The data centers would use a proven, simplified modular design for equipment, which would be placed on a simple sealed concrete floor. The height of the warehouse building would be used to reduce air conditioning requirements with proven low cost techniques.

Data Center Customers

Scientific customers, such as ANU's supercomputer center and government agencies, could be large scale tenants to anchor the development. Some ancillary office space could also be provided.

Twinning

To allow for backup data supplies and exploit the daily solar cycle, the center could be twinned with centers in other time zones. While concentrator solar power stations can store energy, there is still a peak power supply during the day. This peak power could be most efficiently utilised by the data centre under the collectors. A center in another time zone, such as near Perth, would have a peak at a different time of day and could take over some of the processing load from Canberra, as well as providing a backup.

Sighting

The feasibility study raised the issue of the visual intrusiveness of a large field of solar collectors. If placed on top of a warehouse, in industrial parks, the collectors would be less visible. The industrial park could be designed to high environmental standards, retaining natural vegetation around the buildings to soften the visual impact, with the buildings coloured to blend in. In addition the opportunity could be taken to collect high quality water from the complex, for use in Canberra.

Solar Power Plant Pre-feasibility Study
Executive summary

This Solar Power Plant Pre-feasibility Study was undertaken for ActewAGL and the ACT Government (the joint parties) by PB. Its purpose was to investigate solar power generation technologies, identify an appropriate solar technology for the ACT, and establish the economic viability of a solar power facility.

Technology for producing electricity from solar energy is technically proven for both PV and solar thermal technologies. 354 MW solar thermal plants, using trough technology, have been operating in the USA since the 1980s and new plants of this type (between 50 MW and 70 MW) are now coming into service in the USA and Europe. Other solar thermal technologies that are not yet in commercial use are power towers, paraboidal dishes and Fresnel systems. Large multi-megawatt PV plants, to approximately 50 MW, are now in operation. Solar technology is expensive, and significant financial assistance from government is available to the developers and operators of new plants. There is significant local community and market support for solar power generation.

This study identifies a 22 MW project that uses solar thermal trough technology, similar to new overseas plants, as the best option for the ACT. This technology has been chosen because of its substantial operational record (more than 20 years), lower cost compared to other solar technologies, and use in new commercial plants in the USA and Europe.

The plant will produce enough electricity for approximately 10,000 Canberra homes and the project cost, before government assistance, is estimated at $141 million (including land and infrastructure). A site of 120 ha will be required and if engineering, planning and environmental work commenced immediately, it is envisaged that a plant could be
commissioned by 2012.

An alternative option is a large PV cell-based plant. To produce the same amount of electricity (that is, to service 10,000 homes), 75 ha of land would be required and the plant would have an electrical capacity
of 57 MW. This would be one of the largest PV plants in the world but the risks would be lower than the solar thermal plant, reflecting the more mature status of PV technology, its predictable performance and
cost. However, the total project cost of $424 million is high.
It is recommended that this pre-feasibility study be followed by a feasibility study that includes engineering studies, ongoing commercial evaluation, financial modelling and environmental and planning studies.

A staged study, extending over eighteen months, could be conducted and lead directly into procurement and construction. However, trough technology is not cost effective for a staged development at the size
of the proposed ACT plant. Even though the solar field is modular, the balance of the plant is not suitable for staged development without incurring significant additional costs. A financial evaluation of the solar thermal project, assuming 100% equity funding, a 9.5% Weighted
Average Cost of Capital (WACC) and a 20-year project life was undertaken, Key results were:

• a levelised electricity cost of $106/MWh for a net project cost of $47 million. This is for a plant cost of $2,500/kW, which is forecast for the technology in Australa, and allows grant funding of 50% of the project capital cost;
• the relatively high cost of generation is due to the high capital cost of plant itself, the high proportion of infrastructure and land (38% of project cost) and the relatively low productivity (measured by the 42% capacity factor).
• larger plant size would significantly improve the economics by spreading the infrastructure costs over a larger productive plant and capturing economies of scale of the production plant itself. For example, doubling the plant to 44 MW would lower electricity cost by about 25%;
• 57% grant funding was required to reduce the levelised electricity cost to $95/MWh which is the expected Power Purchase Agreement (PPA) electricity selling price;
• higher solar radiation levels such as at Mildura would lower levelised electricity cost by about $50/MWh, or 17% (before rebates); and

Government grants and subsidies have been fundamental to the facilitation of the growth of solar energy generation around the world. The requirement for government support also applies to this project. This
project would appear to fit well with current Australian and ACT Government policies (such as the move toward zero/low carbon emissions and renewable generation) and it supports ActewAGL regulatory
requirements for renewable energy.

The Sun is a reliable but intermittent and diffuse source of energy. There is strong daily and seasonal variation and availability, and it may be limited by cloud cover. To extend power generation beyond periods of sunlight and to allow a steady supply of heat, two approaches to solar thermal plant energy storage were proposed:

• storage of heat at the plant and use of this heat when direct sunlight is not available. This would give an extra four to six hours operation without the Sun shining; and
• use of natural gas as an auxiliary fuel to supply heat as an alternative. If this is supplied by the waste heat from a cogeneration plant, an additional 47 MW could be generated by a gas turbine. The use of gas auxiliary fuel does not affect the eligibility of solar generation as renewable or green energy under the current regulatory arrangements, but may have some impact on community perceptions.

The solar thermal plant would occupy a significant area and unless it is well-shielded, it is likely to be a prominent visual feature. It would combine the physical features of the large solar field with a small
thermal power station, possibly with a gas boiler or small gas turbine for back-up. While the solar technology itself is considered to be relatively benign, it is likely to require consideration environmental issues, that are similar to those raised by a small gas-fired power station with the additional issues raised by the large land area and visual amenity.
Formal evaluations of potential sites for the solar facility will occur only if the project is found to be viable and progresses to a more detailed study, at which time such sites would undergo a rigorous environmental and planning assessment.

From: Executive Summary, "Solar Power Plant Pre-feasibility Study", Parsons Brinckerhoff Australia, (PB 2158583A-RPT001-Qpc, 2 September 2008