'Stat Chat' on A Tale of Two Datasets
SEAI takes a closer look at the datasets highlighting data centre demand and renewable energy generation in Ireland.
The Energy Statistics Team at SEAI collects data from many sources — it runs 650 direct surveys of energy suppliers every year and draws on dozens of datasets from public bodies like the Central Statistics Office (CSO) and Environmental Protection Agency (EPA). Comparing and blending data from different public bodies offers insights and learnings that wouldn’t be apparent from any one agency’s standalone analysis.
Recently, the CSO released new data on electricity demand from Irish data centres that showed growth in both the absolute value and percentage-share of electricity use in that sector.
The CSO analysis is based on a bottom-up summation of metered electricity use and can be rightly regarded as setting a new “gold standard” for evaluating data centre demand.
The CSO analysis is based on a bottom-up summation of metered electricity use and can be rightly regarded as setting a new “gold standard” for evaluating data centre demand.
Reporting on Ireland’s renewable energy portfolio
Similarly, SEAI sets the standard for reporting on Ireland’s renewable energy portfolio. For the specific case of renewable electricity, SEAI tracks both the electricity exported to the national grid from windfarms, solar farms, hydro-electric plants, and combustion of renewable biomass, as well as “behind the meter” generation and consumption from rooftop solar panels, onsite wind turbines, etc.
The availability of these two high-quality datasets — data centre demand and renewable generation — is very timely. Forecasts in the Median demand scenario by EirGrid suggest 23% of all Irish electricity demand in 2030 may be due to data centres, and this has sparked (no pun intended!) very significant public and policy discussions. For example, the Commission for Regulation of Utilities (CRU) recently publishing new rules around data centre connections to the Irish grid. The forecasted increases in data centre demand take place during a period when Ireland is working to achieve an 80% renewable electricity target, a 51% reduction in its carbon emissions, and reduce overall energy demand through efficiency measures — all increasing the scrutiny on the sustainability of large energy users.
Stepping back from these 2030 future forecasts and looking at the measured data available to date from the CSO and SEAI, we see that Ireland has added renewable electricity generation at approximately three times the pace that data centre demand has increased, during the five years from 2015 to 2020.
Renewable electricity generation
From 2015 to 2020 Ireland added an average of 1121 GWh of renewable electricity generation, mostly from wind generation. In the same period, the average increase in data centre demand was 357 GWh. Note that the negative value for additional renewable generation observed in 2016 was due to reduced wind and rainfall compared to the previous year — the total renewable generation in 2015 and 2016 was 7862 GWh and 7513 GWh, respectively. As highlighted in that year’s Energy in Ireland report, 400 MW of additional wind capacity was added in the last three months of 2016, so the full benefit of that investment and increase in renewable generation was not captured until the next calendar year.
| Year | Change in Renewable Generation (GWh) | Change in Datacentre Demand (GWh) | Total Renewable Generation (GWh) | Total Datacentre Demand (GWh) |
|---|---|---|---|---|
| 2015 | - | - | 7862 | 1236 |
| 2016 | -349 | 241 | 7513 | 1477 |
| 2017 | 1369 | 278 | 8882 | 1755 |
| 2018 | 1322 | 417 | 10204 | 2172 |
| 2019 | 1585 | 306 | 11789 | 2478 |
| 2020 | 1680 | 541 | 13469 | 3019 |
This type of “absolute value” comparison is the best approach when looking at numbers from two distinct datasets – this approach is robust and helps preserve the maximum context from the values in both datasets.
By way of contrast, we’ve observed several online articles and discussions that have focussed instead on “relative value” comparisons. This type of analysis can easily lead to mistaken conclusions, because it removes key context from the data.
For example, the relative value increases in 2020 for data centre demand (+541 GWh / 2478 GWh) and renewable electricity generation (+1680 GWh / 11789 GWh) are +22% and +14% for 2020, respectively. This can easily, but incorrectly, be taken to show that that data centre demand (+22%) outpaced added renewable generation (+14%). However, the opposite is true — renewable electricity generation had grown at approximately three times the pace of data centre demand over the previous five years.
| Change in Renewables Generation | Change in Data Centre Demand | |
| 2016 | -349 | 241 |
| 2017 | 1369 | 278 |
| 2018 | 1322 | 417 |
| 2019 | 1585 | 306 |
| 2020 | 1680 | 541 |
The mistake being made here is that the relative value increases from two different datasets cannot (or at least, should not) be directly compared. The normalisation that takes places in the relative value analysis acts to remove a key context — that the absolute value of renewable generation was approximately four and half times larger than data centre demand in 2020 (i.e. 13469 GWh / 3019 GWh = 4.46).
Essentially, a poorly expressed relative value analysis can suggest a false equivalence between similar percentage-changes in both large values (e.g. renewable electricity generation) and smaller values (e.g. data centre demand).
Care must be taken when comparing different datasets
This 'stat chat blog' is not aimed at dismissing or undermining the energy analysis being carried out by third parties. The enabling of informed debate with public data is a key mission of both SEAI and the CSO — we genuinely welcome our data being used to facilitate evidence-based discussions. This blog post is just a timely example of how care must be taken when comparing different datasets to ensure that the full context of the data comes through. If in doubt, then please feel free to contact the Energy Statistics Team at SEAI — we’ll be happy to help.
Also, as the famous saying goes, “past performance is no guarantee of future results”. Just because Ireland had a track record of adding renewable electricity generation at approximately three times the rate of increased data centre demand from 2015 to 2020, there’s no assurance that this trend can or will continue. Ireland has set very ambitious 2030 targets for renewable electricity and reduced carbon emissions — every sector needs to contribute to achieving their relevant emissions ceilings, to set Ireland on a pathway to turn the tide on climate change.