100% Renewable ACT

The ACT Government has a target for 100% renewable electricity by 2020. Most of that renewable energy is coming from wind farms in South Australia, Victoria and NSW, while a smaller fraction is coming from solar farms within the ACT. The electricity from all these wind and solar farms gets fed into the national grid, and no-one really knows where the electricity goes or what fraction is consumed within the ACT. However, the basic idea is that averaged out over a year, the amount of generation coming from the wind and solar farms will match the amount of electricity used by the ACT.

The generation from wind and solar is quite variable. Sometimes there is a lot more renewable electricity than the ACT is using, while at other times there is a lot less, as can be seen in this following chart showing a fortnight of generation (wind=green, solar=orange) and demand (black line). But averaged out over the year, they should approximately match.

There is only a comparatively small amount of electricity storage on the national electricity grid, and as a result, nearly all electricity must be used at the same time as it is generated. Thus, as a result of the variability of the wind and solar generation, it is clear that sometimes ACT demand is being supplied by electricity that was not generated by the wind and solar farms. It is also clear that sometimes the wind and solar generation is greater than ACT demand, and some fraction is therefore supplying users outside of the ACT.

This website aims to answer various questions about the ability of this wind and solar generation to meet the ACT demand. Using 12 months of data from Nov 2018 to October 2019 it is possible to assert the following:

Wind and solar generated 93% of the ACT's net demand over the period.
75% of the ACT's electricity could theoretically have been supplied directly from the wind and solar generation (ie. without the need of any storage)
the remaining 25% would need to have been sourced from other generators on the grid
18% of the wind and solar generation was, at the time it was generated, in excess of the ACT's need, and instead was used by users in other states. It had the effect of greening their electricity supply.
94% of the time wind and solar generation exceeded 100 MW, which corresponds to the average demand requirements of about 125,000 ACT homes.
80% of the time wind and solar generation exceeded 50% of ACT Demand
44% of the time wind and solar generation exceeded 100% of ACT demand.

Moreover, information from the ACT Government to the end of June 2019 also reveals that the cost of the scheme was

$17.50 per MWh, with a breakdown of $6/MWh for the wind projects and $106/MWh for the solar projects
In the 12 months to the end of June 2019, the average cost has been $9 per MWh ($4/MWh for wind and $94/MWh for solar)

Read on if you want to learn more about the ACT target, and how the above values were calculated.

Explanation of the 100% renewable electricity goal.

The ACT Government has a target for 100% renewable electricity by 2020. It plans to achieve this through a few different routes:

It has signed contracts with large-scale wind and solar farms with predicted generation representing approximately 3/4 of the ACT's demand.
Approximately 5% of ACT electricity is expected to come from rooftop solar within the ACT.
The remaining ~20% is to be sourced from the ACT's share of the national renewable target with a small residual from GreenPower purchases.

The contracts with large-scale wind and solar farms work in the following way. The ACT guarantees the wind and solar farms will receive a given price for every MWh of electricity that they generate, through a contract for difference (CfD) scheme. The guaranteed price is shown the table below. In return, the ACT gets the renewable certificates (LGCs) from the projects, which are then cancelled in order prove the generation to be additional to the National Renewable Energy Target. These LGCs are what are used to justify the claim to being powered by renewables.

The contracted wind farms are located in South Australia, Victoria and NSW, and the solar farms are in the ACT. All electricity generated is fed into the national electricity grid. It does not go directly to ACT consumers. The output of the wind and solar farms is also quite variable, and does not correlate with the ACT's demand. Both of these points have led to criticisms that the ACT claim of 100% renewable is not valid. This website aims to provide some facts regarding the second point, by investigating how the variability of the wind and solar generation relates to ACT demand.

It should be noted that the 100% renewable target is for 2020. While most contracts between the wind and solar farms and the ACT Government have commenced, the final contract does not until October 2019. However all the wind and solar farms have been generating at full capacity and exporting to the grid since November 2018, and the analysis in this website assumes all generation has been contracted since this date. More details about the projects are provided in the following table.

Monthly Results

The figure above summarises the monthly results. The green and yellow columns indicate the average power delivered by wind and solar during the month respectively, while the solid black line shows average ACT demand. The red dotted line shows the ratio of the average power delivered by the wind and solar to demand. Thus, in some months the wind and solar farms supplied more electricity than was needed by the ACT. In other months it supplied significantly less. In particular, demand is much higher during the winter months in the ACT, and renewable supply tended to be much lower than demand during this season.

The blue dotted line shows the fraction of ACT demand that theoretically could have been supplied directly (without storage) by the wind and solar during the month. In other words, when looking at the fortnightly chart at the top of this page, the blue dotted line represents the fraction of the area under the black demand line that is covered by renewable generation. It is equal to the red dotted line minus the fraction of renewable generation that was excess to ACT's needs at the time it was generated.

Renewable generation Probability of Exceedance charts

The blue curve in the following chart indicates the fraction of the time that the wind and solar farm generation exceeded various generation levels, based on the 30 minute generation data. From the chart, it can be seen that about 94% of the time, wind and solar generation exceeded 100 MW, which is the average demand requirements of about 125,000 ACT homes. About 44% of the time, renewable generation exceeded 320 MW, which is approximately the average demand requirements of the ACT. The second chart is similar, except it shows the probability that the wind and solar generation exceeded various percentage levels of ACT demand. It shows that 80% of the time renewable generation exceeded 50% of ACT demand, and 44% of the time it exceeded 100% of ACT demand.

Fortnightly charts

Each of the following charts show the renewable generation over a fortnight at a 30 minute resolution. The green tinged areas represent wind generation, while the orange/yellow tinged areas represent solar generation. See the explanation notes at the end of this report for more information about how all these quantities were calculated.

Detailed Explanation Notes

Green areas in the fortnightly charts represent generation from wind farms: Coonooer Bridge (Vic), Ararat (Vic), Crookwell (NSW), Hornsdale 1, 2 & 3 (SA) and Sapphire (NSW). Data is obtained from AEMO. The ACT has contracted only part of Ararat (33%) and Sapphire (37%) wind farms, so the AEMO data from these projects has been scaled by these percentages. There is also a green component indicated by LRET wind, which indicates an estimate of ACT's share of wind generation on the NEM due to the LRET and the residual GreenPower purchases. It is obtained by scaling total NEM wind by a slowly diminishing percentage, as explained in the final dot point below.
The yellow area represents generation from utility solar: Royalla, Williamsdale, Mugga Lane and Majura, all within the ACT. AEMO data is only available for Royalla and Mugga Lane, and total utility data has been estimated by adding the Royalla and Mugga Lane data and then scaling by 143%, representing the ratio of total utility solar capacity to the capacity of Royalla and Mugga Lane. There is also a dark orange component indicated by LRET PV, which indicates an estimate of ACT's share of utility solar generation on the NEM due to the LRET and residual GreenPower purchases. It is obtained by scaling total NEM solar by a slowly diminishing percentage, as explained in the final dot point below.
The brownish area represents generation from rooftop solar within the ACT. It is estimated by scaling NSW rooftop generation as obtained from AEMO by 4.9%, which is approximately equal to the ratio of the installed capacity of rooftop PV in the ACT to that in NSW, as indicated by the Clean Energy Regulator.
ACT demand up to July 2019 was obtained from Evoenergy. This substation data has units of MVA, which you would expect to be 11% larger than the corresponding MW values. However the substation data excludes data delivered via the high voltage network which comprises about 12% of ACT demand. Cross-checking with data submitted by Evoenergy to the AER suggests that the substation MVA data agrees very well with annual total demand (mean =0.2%, stdev=1.4%), and thus this data has been used to estimate ACT demand. Data after July 2019 is not available till mid 2020, so in the meantime it has been estimated by scaling NSW demand by a matrix of scale coefficients. The matrix is a function of time of day and month, has an average value of 4.0%, a maximum value of 5.1% for 7am in August and a minimum value of 3.0% for midnight in February. This matrix of scale coefficients relates demand in the ACT to demand from NSW, and was calculated using the ratio of ACT to NSW demand from the 2018-2019 financial year. Rooftop PV is then added, as it is excluded from both NSW and ACT demand data sets. NSW data is obtained from AEMO.
Crookwell wind farm only reached full capacity in November 2018. That is why this analysis starts in this month. I intend to update this web-page on a semi-regular basis, hopefully monthly.
The contract between the ACT Government and the Hornsdale 3 wind farm does not commence till October 2019. The wind farm has, however, been providing generation into the grid for a couple of years, and this analysis has assumed that it is contributing to the ACT target during the entire period. Its contribution represents ~12% of ACT demand.
The analysis does not consider the impact of loss factors. Note that LGCs are calculated by multiplying generation by the marginal loss factor (MLF) of each generator. A more detailed analysis including loss factors would be required to calculate if the ACT had obtained sufficient LGCs in order to satisfy its claim to be 100% renewable.
The LRET + Greenpower components have been calculated by scaling NEM renewables by a slowly diminishing percentage, starting at 3.6% in Nov 2018, decreasing to 2.5% by the end of October 2019. This percentage represents the fraction of NEM renewable generation that would be required to meet approximately 20% of ACT demand over a year. Since NEM renewables are increasing each year, but ACT demand has remained fairly constant over the last decade, the scaling percentage decreases over time. The renewable power percentage is expected to be approximately 20% in 2020, and this analysis has assumed that the GreenPower residual will be relatively small.

Costs:

Quarterly data on the costs of the Contract for Difference (CfD) scheme can be obtained from the ACT Government here, though it often has a lag of several months. The table above shows the CfD price for each project. Each project sells their electricity on the wholesale market. If they sell it for less than the CfD price, then they get topped up to the CFD price. If the project sells their electricity for more than the CfD price, then they have to refund the difference. In return for guaranteeing the price, the ACT Government gets to keep the Renewable Energy Certificates. In simple terms the CfD scheme can be thought of as an economic way of purchasing renewable certificates directly from the renewable generator. The following image shows the cost paid to each generator per MWh of generation over the last couple of years. This cost represents the cost of the certificates to the ACT. It is clear that the cost of the scheme from solar generation is comparatively high, around $100 per MWh, while the cost from wind is usually less than $20/MWh. As more wind generation enters the scheme, the weighted average cost has come down substantially. During many quarters, the cost of the scheme from some wind projects has been negative! Some key highlights of the cost data are:

Since the inception of the scheme, the average cost has been $17.50 per MWh ($106/MWh for solar, $6/MWh for wind)
In the 12 months to the end of June 2019, the average cost has been $9 per MWh ($94/MWh for solar, $4/MWh for wind, -$12.50/MWh for Coonooer!)
In the quarter ending March 2019, the total cost of the scheme was -$4.3 million, or -$11/MWh! The scheme was saving money rather than costing money.

Disclaimer: This website has been created by David Osmond, who has worked in the renewables industry for nearly 20 years. David has worked at Windlab since 2003, and Windlab developed one of the wind farms which won a contract with the ACT Government for supply of renewable energy, Coonooer Bridge Wind Farm. The work presented here is his own, and is not endorsed by Windlab.

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