Hybrid wind and solar farms likely to deliver significant cost savings

A total of at least 1GW of large-scale solar could be added to existing Australian wind farms, boosting renewable energy development, generation, and and smoothing its delivery to the grid, according to a new report from the Australian Renewable Energy Agency investigation the benefits of solar and wind “co-location.”

Based on data from 10 existing wind farms around Australia, the report – released on Monday and previewed last Thursday at the Wind Wind Industry Forum in Melbourne – found that major savings could be achieved for developers using co-location, particularly in the grid connection infrastructure.

“It is well known that the development costs and timescales for renewable projects in Australia can be significant barriers for renewable projects, placing pressure on the upfront investment requirements of developers,” the report said. “By co-locating wind and solar farms, synergistic gains can be achieved to help reduce overall cost.”

It’s not a completely new idea – already, numerous developers in Australia are either adding solar to existing wind projects or seriously considering it.

Chinese wind giant Goldwind, for example, announced plans in February to add up to 12MW of solar at its jointly owned Gullen Range wind farm in the NSW Southern Tablelands. CWP is looking to combine wind and solar in a major project near Glen Innes in northern NSW, and the biggest hybrid plant of all – the 1,200MW Kennedy wind and solar project has been proposed for north Queensland.

The ARENA report – based on research conducted by AECOM – confirmed “significant potential” for wind and solar co-location at “numerous locations where the two renewable resources are highly complementary,” both for existing wind farm sites and for greenfield projects.

It found that the greatest brownfield co-location opportunities were currently in Western Australia and South Australia, thanks to a good solar resource, a complementary generation profile and higher wholesale market prices. The best greenfield opportunities were also found in South Australia and Western Australia, as well as parts of Queensland and small parts of New South Wales.

Of the 10 wind farms analysed, the report found that 414MW of solar capacity could be co-located without exceeding 5 per cent curtailment. AECOM also analysed the financial merit for solar plants at each existing wind farm site by indexes that represent the costs and revenues of each site relative to a benchmark site. (see Figure 1 below).

The report estimated total cost savings of co-location to be between 3-13 per cent for capital expenditure and 3-16 per cent on operational expenses. On top of this, there was significant potential for a boost to revenues, with more energy being produced at a more consistent rate.

But one of the more important benefits of solar and wind co-location, highlighted at last week’s conference, is its potential to aid grid integration for renewable energy as more and more wind farms are added to national networks.

“Given the intermittent nature of renewable technologies, pairing resources in regions dominated by one particularly technology will likely have a “firming” effect,” the report says. “This reduction in the overall facility’s degree of intermittency results in an improved capacity factor at the connection point and can mitigate associated network constraints in regions dominated by a single generation type.”

As AECOM principal engineer Joep Vaessen noted at the Wind Industry Forum the study found that Western Australia, in particular, lent itself for co-location opportunities, with a pattern of a dip in wind generation in the middle of the day counter-balanced by the energy from the midday sun.

As you can see in the charts above, Western Australia is characterised by lower average daytime generation across all three analysed wind farms. This characteristic is particularly pronounced at Collgar and Alinta wind farms, which provides more headroom for daytime solar generation.

Similar patterns of low day-time generation were observed at the South Australian wind farms, although to a lesser extent. Wind farms in NSW and Victoria did not consistently follow this pattern.

The study’s key findings:

– Cost savings: Major savings can be obtained in the grid connection equipment and installation, operation and maintenance and development costs (including land costs, development approvals and studies). These savings are estimated at 3 to 13 percent for CAPEX and 3 to 16 percent for OPEX.

– Prospective regions: The greatest brownfield co-location opportunities are currently in Western Australia and South Australia, where there is good solar resource, a complementary generation profile and higher wholesale market prices. The best greenfield opportunities for wind-solar co-location are also found in South Australia and Western Australia, as well as parts (non-cyclonic) of Queensland and small parts of New South Wales.

– Importance of network access; Many of the greenfield sites are not close to the network, or are adjacent to weak parts of the network. While this creates a challenge for developers, there may be an opportunity for NSPs and policy makers to intervene by opening up regions of high natural wind and solar resource through new network assets.

– Co-location potential: The technical capacity of existing wind farms to accommodate co-located solar farms is estimated at over 1 GW. Growth in renewables driven by the Renewable Energy Target is expected to open up technical capacity for an additional 1.5 GW of solar PV to be co-located at new wind farms built by 2020. However, the relative financial competitiveness of these opportunities (combined with relevant policy) may limit the uptake of the full technical potential of co-location.

– Firming effect: Given the intermittent nature of renewable technologies, pairing resources in regions dominated by one particularly technology will likely have a “firming” effect. This reduction in the overall facility’s degree of intermittency results in an improved capacity factor at the connection point and can mitigate associated network constraints in regions dominated by a single generation type.