Clear · ΔT > 5 °C
- Komorebi hybrid92
- Dry cooler + adiabatic88
- Dry cooler + chiller95
- Radiative panels48
The case
The application that gets picked.
Cooling performance
The interconnect approval queue decides who wins compute capacity — not GPUs. Undifferentiated 50 MW interconnect filings wait. You are not buying solar. You are buying an existing grid connection and filing a load the operator can say yes to. Texas (Pecos) is the worked example. The same two clocks exist on every grid: power out, and permission to pull power in after dark.
- CFO
- Economics
- CTO
- Cooling & generation
- Counsel
- Permitting
$150M/year on 50 MW firm. $333M/year on 111 MW firm. 154 MW flex is extra hours.
50 MW holds on the hottest design day. 54 MW is the modeled meter draw at PUE 1.08, not a site cap — versus 62.5 MW at PUE 1.25.
Use the generation permit you already have. Phase 3 is a residual plant — 50 MW inside an air permit that would refuse 54 MW of engines.
Why 50 MW holds when outdoor air is as hot as the cooling loop.
Pecos, Texas · grid-tied · existing PV interconnect · Phase 1
Comparison of three cooling solutions for 50 MW of AI compute
Two comparisons, same Pecos farm. First: an already-connected solar deed becomes a 50 MW IT host — a site with no interconnect and no 24/7 heat sink this year is 100% of nothing in IT offtake. Second: 8.5 MW less parasitic load versus PUE 1.25 at the same 50 MW IT (54 MW modeled meter draw at PUE 1.08, not a site cap). The farm stays on the grid. Reciprocating engines are not in this table; they are a later option.
| Metric | Dry cooler + chiller | Dry cooler + adiabatic | Komorebi Phase 1 | V% |
|---|---|---|---|---|
| PUE | 1.25 | ~1.18 | 1.08 | −14% |
| Overhead at the meter | 12.5 MW | ~9 MW | 4 MW | −68% |
| AI compute hosted | 50 MW | 50 MW | 50 MW | — |
| Draw from PV + grid | 62.5 MW | 59 MW | 54 MW | −14% |
| Annual cooling water | ≈ 0 | ~73 Mgal/y | ≈ 0 after fill | — |
| Plant noise at 10 m (est.) | ~80 dBA | ~70 dBA | ~55 dBA | −25 dB |
| Cooling electricity OPEX | $3.8M/y | $2.8M/y + water | $0.2M/y · pumps only | −95% |
| CAPEX per MW of AI compute | ~$1.5–2.0M / MW | ~$1.2M / MW | ~$0.6–0.9M / MW | ~−50% |
CAPEX is the cooling overlay per MW of AI hosted, screening, not a bid. Komorebi Phase 1 is 50 acres of finned tables + Ø800 foundation pipe, not the whole PV field. Cassettes ~$11M, coated Ø800 ~$21M; extra tracker steel, manifolds, pumps, glycol, I&C take the screen to ~$30–45M for 50 MW (~$0.6–0.9M/MW). Dry-cooler and adiabatic columns are mechanical yards. UPS/electrical of the hall is in the 4 MW overhead, not in this overlay. OPEX at $35/MWh. AI at $3M per MW-year is a planning offtake, not a quote.
Eight-day Pecos screen on the radiator campus: 50 MW firm served in the window, PV held at 100 MWdc, 50 acres reserved for tables. A full-year radiator-campus run is not yet the published design target. Prior whole-field radial year is not this plant. A 10 MWdc pilot — about 5 MW of firm IT — is the step that validates hot-day performance, parasitic demand, and ground-temperature behavior at commercial scale.
Plant noise is a 10 m estimate at the cooling cluster, not a property-line model. Chiller yards ~75–85 dBA (compressors + condenser fans). Adiabatic dry coolers ~64–73 dBA per unit at 10 m in manufacturer data; ~70 for a yard. Komorebi is pumps and Ø800 under radiator rows — dry coolers as backup only — ~50–60 dBA outside a pump enclosure. −25 dB is about one-sixth as loud.
Pecos, Texas temperature envelope
Monthly air temperature. Left axis °C, right axis °F. Highs ~17 °C / 63 °F in January to ~37 °C / 98 °F in June–July.
- High
- Mean
- Low
Clear vs cloudy hours
Share of time. Clearer hours help dry and radiative duty; cloud still matters in winter. NSRDB 2024.
- Clearer
- Cloudier
More compute. Naturally.
Cooling performance
Pecos, Texas · challenging weather, firm rejection
In Pecos, Texas the hard hours are not the average hour. Clouds close a purely radiative sink. A dry cooler cannot go below ambient. A chiller can, but it spends the watts you wanted for compute. Komorebi keeps a buried inventory and uses a heat pump to bank cold, so the loop still rejects when approach temperature is zero or negative and the sky is no longer a window.
Range across the year
Lower is better. Monthly cooling electrical demand to hold 50 MW of AI compute. Median marked.
Komorebi hybrid
3–5.3 MW, median 3.73.7MW
Dry cooler + adiabatic
7.3–11.4 MW, median 8.48.4MW
Dry cooler + chiller
10.2–15.6 MW, median 11.811.8MW
Radiative panels
2.9–5 MW, median 3.53.5MW
Bar is the inner half of months. Whisker is the full monthly range. Number is the median, MW.
Does the sink still work when weather turns?
Firm heat-rejection capability, 0–100. A chiller always rejects — and spends the watts you wanted for compute.
Cloudy · ΔT > 5 °C
- Komorebi hybrid86
- Dry cooler + adiabatic82
- Dry cooler + chiller93
- Radiative panels22
Clear · ΔT ≈ 0
- Komorebi hybrid78
- Dry cooler + adiabatic28
- Dry cooler + chiller90
- Radiative panels62
Cloudy · ΔT ≤ 0
- Komorebi hybrid70
- Dry cooler + adiabatic18
- Dry cooler + chiller88
- Radiative panels8
Tight band
Soil inventory and a heat pump buffer the Pecos, Texas summer peak.
Cheap on kWe
Radiative demand looks low until clouds remove the sink.
Pecos, Texas problem set
Clouds plus low or negative approach. Hours that decide available cooling — and therefore compute.
Heat-pump storage
Banked lift keeps rejection available at ΔT ≤ 0 when radiative falls off.
Left: electricity to hold the same cooling duty, in MW. Right: whether rejection remains available. Illustrative Pecos, Texas envelope — not a live plant meter.
Land · same fenceline
Same 100 MWdc fenceline. Denser PV. Ten percent of tables become the cooler.
A 2015 tracker field uses about 5 acres per MWdc. This case re-modules that fenceline with 700 Wp bifacial (~3.13 ac/MWdc, GCR 0.35). Fifty acres (~10%) convert to open-finned radiator cassettes on Alion AST 1.2. Under those rows only: a half-buried Ø800 mm pair (foundation + 70 °C loop). Remaining PV stays generation, GCCM pad, no cooling pipe. Leftover acres (~137) can take Phase 2 CSP steel on concrete rail — aperture in the ground, not a commissioned power block. TES and ORC stay Phase 2.
XOR pads — never stacked: PV = GCCM · radiator = Ø800 pair · CSP / windward = concrete rail. On 500 acres: 100 MWdc PV (~313 ac) + 50 ac radiators + ~94 MWth CSP leftover (~137 ac). CSP is not the Phase 1 cooler. Do not credit Ø800 under PV or CSP.
The ground
An optional sink. Not the whole plant.
Phase 1 cooling is the radiator reservation. Ø800 sits half-buried under those rows only. Ground coupling beyond that pipe is site-specific — soils, year-round heat balance, and more than one summer of measurement. In a warm desert, an atmospheric sink may beat the ground. Dry coolers stay as fail-safe. The ground is an optional sink, not the platform.
Pecos, Texas · 100 MWdc existing PV · 50 MW firm AI
How the 50 MW is served across a day
Komorebi Phase 1 does not create the 50 MW. It stops cooling from consuming it. On an existing 100 MWdc farm that already has 2-hour batteries, parasitics fall from 12.5 MW of compressors to 4 MW of pumps — 8.5 MW continuous, 204 MWh/day. That is the headroom at the interconnect for 50 MW of 99.9% firm AI, and it is the midday surplus that charges heat-pump cold storage instead of feeding chillers. Phase 2 recovers server heat and adds CSP into TES/ORC — better PUE, and a filing the grid operator can tell from PV and batteries alone. That thermal plant is the filing, and the plumbing Phase 3 uses. It is not booked as a second offtake. Phase 3 drops the grid by converting heat to electricity. Engines last: a residual plant, not a 54 MW yard.
Peak PV 76 MW AC. Dry coolers stall — outdoor air is nearly as hot as the ambient cooling loop, so they cannot reject 50 MW of server heat. The MPC has already run the heat pump and topped up cold storage. Midday surplus after the 50 MW load goes into cold storage first, then the batteries.
Cooling stall (what operators call approach temperature): the gap between the hot cooling loop and outdoor air. When that gap shrinks toward zero, dry coolers stop moving heat. The heat-pump cold bank covers those hours.
Phase 1 — cooling first
This chart is the +50 MW. The dashed 50 MW line is filled all day on the existing 100 MWp interconnect: PV while the array is up, 2-hour BESS after sunset, grid only overnight. Midday surplus charges heat-pump cold storage so cooling does not consume the 50 MW. Komorebi draws 54 MW at the meter; the hatched band is the 8.5 MW a chiller would add (62.5 MW) — and on this stall day dry coolers would not hold the load.
PV to load 628 MWh · BESS discharge (after sunset) 100 MWh · BESS charge 102 MWh · Grid 472 MWh
After 17:00 the bank dumps into the hall — stall, surplus gone. After 20:00 outdoor ΔT returns and the field recharges it overnight. No night compressor on the grid.
- PV to load
- PV available
- Midday surplus → cold store + BESS
- Chiller tax (8.5 MW)
- BESS discharge (after sunset)
- BESS charge
- TES / ORC
- Generators · 54 MW recip.
- Grid
- CSP to TES
- Heat Pump Cold Storage
- Generator heat to TES
- 50 MW firm
+50MW
additional firm AI
Cooling: heat pump in service — dry coolers stall
Phase 2 — AI heat recovery and CSP uplift
Phase 2 is what a PV-and-battery filing does not have. Recovered server heat (~14 MWth off the rejector) and CSP charge TES. TES/ORC runs ~6 MW through the day from that heat, and covers the late night with stored CSP — PUE 1.08 → 1.05. Marginal megawatt-hours. The value is the filing, the environmental envelope, and the smaller engine Phase 3 is then allowed to be. Heat-pump cold storage still banks midday surplus; the evening dump is shallower because the hall is already lighter.
PV to load 556 MWh · BESS discharge (after sunset) 88 MWh · BESS charge 102 MWh · TES / ORC 275 MWh · Grid 281 MWh
- PV to load
- PV available
- Midday surplus → cold store + BESS
- Chiller tax (8.5 MW)
- BESS discharge (after sunset)
- BESS charge
- TES / ORC
- Generators · 54 MW recip.
- Grid
- CSP to TES
- Heat Pump Cold Storage
- Generator heat to TES
- 50 MW firm
+14MW
CSP/ORC uplift to the 50 MW · AI heat recovered
Cooling: heat pump in service — dry coolers stall
Phase 3 — residual plant · off-grid
TES/ORC holds ~32 MW overnight from CSP, recovered heat, and exhaust, so recip shaft only covers ~22 MW. Today's midday surplus still charges the 100 MWh battery; we discharge it after sunset to displace genset MWh — stored PV is cheaper than fuel. Without TES/ORC the islanded plant is the full 54 MW Komorebi meter — 62.5 MW if the hall were chilled. That larger genset is the air, noise, and water filing that often fails. The residual plant is what permits. Growth past 50 MW is recovered heat, not a bigger stack. No grid.
PV to load 556 MWh · BESS discharge (after sunset) 38 MWh · BESS charge 102 MWh · TES / ORC 431 MWh · Generators · 54 MW recip. 175 MWh · off-grid
Midday surplus PV charges the pack today. We discharge after sunset to displace genset MWh: stored PV is cheaper than fuel, hours, and permit burden on the recip fleet.
- PV to load
- PV available
- Midday surplus → cold store + BESS
- Chiller tax (8.5 MW)
- BESS discharge (after sunset)
- BESS charge
- TES / ORC
- Generators · 54 MW recip.
- Grid
- CSP to TES
- Heat Pump Cold Storage
- Generator heat to TES
- 50 MW firm
50MW
islanded off-grid · 22 MW recip shaft after TES/ORC · 54 MW fleet without TES/ORC — the permit problem
Cooling: heat pump in service — dry coolers stall
22 June Pecos, 100 MWp conversion farm, inverter clip 76.2 MW AC. PV to the 50 MW load; surplus first into the heat-pump cold bank, then batteries. Phase 2 TES/ORC is recovered server heat (~6 MW around the clock) plus stored CSP at 27.5% ORC. Phase 3 drops the grid. TES/ORC from CSP, recovered heat, and exhaust covers most of the night; recip shaft is the residual (~22 MW this day). Without TES/ORC you would install and run the full 54 MW fleet — 62.5 MW if the hall were chilled. Heat-pump cold storage is a 30 MWth bank; it is cooling, not electrical supply to the 50 MW. A planning day, not a forecast.
The farm arrives with 2–4 hours of BESS. Charts use the 2-hour floor: 50 MW / 100 MWh. Summer charges from midday surplus after the heat pump. Winter Phases 1–2 charge overnight from cheap grid. Discharge is after sunset only — never while the array is producing. Phase 3 is islanded: summer still charges from today's surplus; winter cannot, so that discharge is carry-in from a prior sunny day. The pack is never charged from the genset.
Dotted gold is unclipped PV. Gold fill above 50 MW is surplus: first into the heat-pump cold bank (COP 3.5, 30 MWth — the steel-blue band on the electrical chart), then the 100 MWh battery. The hatched red band at 54–62.5 MW is the chiller tax — 8.5 MW you would draw every hour, and do not. Heat-pump cold storage is cooling, not electrical supply to the 50 MW.
Compared with
Heat has to go somewhere.
Four substitutions a facilities team will offer. The stall day is the test — not PUE in isolation.
Warm-water liquid cooling and dry coolers
That path can reach a similar PUE on a campus that already has power. On a stall afternoon outdoor air matches the loop. Dry coolers stop. Adiabatic buys those hours with water the permit often will not give.
More batteries
Batteries store electricity. They do not reject heat. Every MWh spent running chillers is a MWh that never reaches GPUs.
Chillers on midday surplus
Noon PV can cover a 62.5 MW chiller hall. After sunset the array is dark. On stall hours dry coolers cannot dump 50 MWth.
CDUs and liquid-to-chip
They move heat out of the rack. They still need a place to dump 50 MWth when outdoor air equals the loop. That place is the 50-acre radiator reservation.
Why the overlay beats a new plant
- Lower capex per additional MW of AI than recips or simple-cycle GTs — and no new water right or chiller-yard air permit
- Reuses the interconnect and land you already have, or makes a campus you already permit hold more IT
- The array stays PV. A 50-acre radiator reservation is the 24/7 cooling plant — then AI compute on the interconnect you already have
- If overnight service is delayed — or the air permit cannot take 54 MW of engines — Phase 2 TES/ORC is already in, so the islanded plant is ~22–28 MW, not a 54 MW engine yard