Power before floor area: a grid-capacity decision guide for project teams
A power purchase agreement, a battery and a network upgrade solve different problems. Before committing to a site or a delivery date, establish the electrical load you need, where it must be delivered, when it must be available and what interruptions the operation can tolerate. Then select the response. The dated data-centre examples below show why adding headline megawatts is a poor substitute for this brief.
Part 1 of 4: What the data-centre build-out is teaching construction.
Transgrid links additional Sydney data-centre connections to user-funded upgrades
Transgrid’s 26 August 2026 statement reported 20 GW of enquiries for large-load connections and insufficient unallocated Sydney transmission capacity to accommodate them. It said additional data-centre connections would depend on customer-funded network upgrades. Enquiries describe interest, not committed demand.
Transgrid's other figures, each with a different status:
- Allocated: about 1.5 GW associated with signed Western Sydney data-centre connection agreements.
- Identified: upgrades that could release up to 2 GW more capacity, including the proposed South Creek substation.
- Funding: the proponents creating the need would bear the identified upgrade costs.
- Allocation: signing connection agreements and committing upgrade funding would determine the order.
This is a dated account of one constrained network area, not a national connection rule. Ask the relevant network business for the connection conditions for your site and development stage. An indicative capacity discussion is not a guaranteed energisation date.
Paying neighbours to use less is a capacity product in a specific market
Google and Voltus announced a three-year PJM agreement in June 2026 for up to 100 MW of flexible capacity. Voltus would coordinate resources such as batteries and smart thermostats at participating premises and pay customers for their contribution. This can reduce demand at constrained times; it does not build a dedicated supply cable to Google’s site.
Voltus announced a larger agreement in October 2026. Its release uses both a 1 GW headline and an additional 1,070 MW description. Those figures are not reconciled here, and neither proves delivered capacity. For a project decision, request the contracted quantity, location, availability and measured performance.
The transferable question is whether demand can be reduced where and when the local network needs it. Ask the electrical engineer and network business whether the proposed response is recognised, controllable and dependable under the connection arrangement. An overseas capacity-market agreement does not establish an Australian approval pathway.
On-site and dedicated supply: separate the contracted from the operating
Fuel cells beside the hall. Bloom Energy’s April 2026 release distinguished an intention to procure up to 2.8 GW from 1.2 GW already contracted for Oracle. It also reported a separate operational installation delivered in 55 days, without stating its size. The release does not establish the fuel or emissions of the Oracle fleet. Before using this example in a programme, confirm fuel availability, permitted emissions, maintenance redundancy and the actual capacity deliverable at your site.
Geothermal supply. Fervo reported that its first 33 MW Cape Station block reached commercial operation on 30 September 2026. Separately, its September announcement described a 396 MW Google power purchase agreement for supply expected in 2028, subject to further project conditions. The operating plant and the future supply agreement are different commitments. A generation contract also needs a workable network delivery arrangement.
Multi-day storage. Xcel’s February 2026 announcement proposed a 300 MW, 30 GWh iron-air battery within its Google supply arrangement. It described dispatch to the grid, not dedicated backup for the data hall. The proposal required regulatory approval. Minnesota’s Attorney General subsequently challenged its cost allocation and stranded-cost protection; that is an advocate’s position, not a Commission finding. Treat this as a dated proposal, not evidence of an approved or operating asset.
Worked check: storage capacity is not an energy supply
Hypothetical example, not a project result: 30 MWh of usable delivered energy divided by a constant 10 MW load gives three hours of supply. This assumes the battery can continuously deliver 10 MW and starts with that usable energy available. It does not establish a recharge source, uninterrupted backup or a new network connection. If part of the store is reserved for backup, the same energy cannot also be committed to routine peak reduction.
Which constraint does each option actually change?
Makao’s decision framework below is engineering judgement drawn from these examples. Apply it to the site, not to the supplier’s headline. MW measures power; MWh measures energy over time. Neither alone establishes resilience.
Option | Constraint it may address | Evidence needed before relying on it |
|---|---|---|
Network upgrade | Physical transfer capacity at the connection point | Network-approved scope, funded works, capacity conditions and energisation programme. |
Flexible demand | Demand during specified network events | Location, response MW, duration, notice, dispatch obligations and network acceptance. Test operational consequences. |
On-site generation | Net import demand; resilience if designed for it | Firm output, fuel logistics, emissions, maintenance and protection. Demonstrate any islanded operating mode. |
Off-site supply contract | Procurement of electrical energy | Delivery point, timing, volume profile and network arrangements. Do not add contracted MW to site connection capacity. |
Storage | Time mismatch between supply and demand | Usable MWh, continuous MW, duration, recharge window, losses and reserved backup capacity. Do not count the same capacity twice. |
Before the next feasibility meeting, ask the electrical lead for a one-page power brief: staged peak demand and load profile; required connection date; agreed import limit; interruption tolerance; options against the matrix; unresolved dependencies; and the person responsible for each decision. Have the operator confirm which loads can genuinely stop or shift. If the concept depends on unconfirmed capacity, carry that dependency explicitly into the site and programme decision.
Once the supply and connection constraints are understood, test the cooling demand with the water-saving and heat-reuse questions because the cooling arrangement also affects the energy brief.
Sources
Dated source examples. Company announcements establish what was stated, not independently measured performance. The decision matrix is Makao’s synthesis.
Questions or corrections: contact Makao.
