IEEE Power & Energy Magazine - September/October 2021 - 58

REZs
The concept of a REZ has gained international traction over
the past decade, and several projects have already been implemented,
such as the competitive REZs formed in Texas between
2005 and 2014. At AEMO, we set out to learn from these experiences
when creating a plan for the Australian grid. The starting
point was to agree on a definition for a REZ. While several were
already in use, they were often too specific for our purposes.
We decided on a definition that would be flexible and future
proof. A REZ is defined as " an area where clusters of large-scale
renewable energy can be developed using economies of scale. "
With a definition in mind, a selection of candidate REZs
was needed. That is, where might these REZs be located? As
outlined in the 2020 ISP, AEMO engaged the consultant DNV
GL to provide information on the resource quality for potential
REZs. A wind resource quality assessment was provided
based on mesoscale wind-flow modeling at a height of 150 m
above ground level (a typical wind turbine hub height). Global
horizontal irradiance and direct normal irradiance data from
Australia's Bureau of Meteorology were used to assess the
solar resource quality.
The results of the initial resource quality investigations
are shown in Figure 2. This analysis generally shows that
solar resources are greatest toward northern and central
Australia, and wind resources are highly locational. Based
purely on this information, it would seem logical to locate
a REZ in northern Queensland-at the top of the map-
where solar and wind resources are both rich. However,
as we quickly discovered, a successful REZ depends on
many more variables than just resource quality.
With a wealth of resource quality information, AEMO
hosted industry workshops to gather information about what
10
15
20
25
30
35
5
could make a REZ successful. Through these workshops, 10
scoring criteria were identified to inform the candidate REZ
selection. These criteria are specified (from AEMO's website) as
✔ wind resource: a measure of high wind speeds (above
6 m/s)
✔ solar resource: a measure of high solar irradiation
(above 1,600 kW/m2)
✔ demand matching: the degree to which the local resources
correlate with demand
✔ electrical network: the distance to the nearest transmission
line
✔ cadastral parcel density: an estimate of the average
property size
✔ land cover: a measure of the vegetation, water bodies,
and urbanization of areas
✔ roads: the distance to the nearest road
✔ terrain complexity: a measure of terrain slope
✔ population density: the population within the area
✔ protected areas: exclusion areas where development
is restricted.
The results of this criteria-weighted resource scoring are
shown in Figure 3. With wind and solar resource weightings
reduced to just 35% and 30% of the total score for each
map, the resulting graphic highlights new areas that could be
ideal REZs. The results of this analysis and the weightings
assigned to each criterion were benchmarked against active
feasibility studies to ensure that a successful REZ would
generally align with investor interests.
When conducting this analysis, we were limited to the data
available for macroscale modeling. Notably, some important
data remain unquantified, including social license, environmental
impacts, native title, and alignment with government initiatives
for regional growth. While it is
paramount for these considerations
to be assessed before committing to
individual projects, it simply wasn't
feasible at this early stage in the process.
An individual candidate REZ
might span tens or even hundreds of
thousands of square kilometers, and
there are limitless ways of realizing
the infrastructure needed to unlock
its potential.
Based on the 10 scoring criteria,
Black Coal
Fast Change
Brown Coal
Step Change
Gas
Central Estimate
Slow Change
figure 1. The reduction in fossil-fueled generation capacity. (Source: AEMO; used
with permission.)
58
ieee power & energy magazine
35 candidate REZs were defined
geographically, as shown in Figure
4. The generation and storage
icons in this figure broadly indicate
the forms of developer interest that
might be expected if a REZ were
implemented. These initial candidate
REZs were subject to revision
and will continue to be evolved.
They have already been adjusted
several times based on consultation
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IEEE Power & Energy Magazine - September/October 2021

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