Combined study · directional only
Shaft Apex is a daylight machine: four 3,000 m collectors, a split beam, and heat that lasts days. The other half of a megalith is what highland schemes already chase in public — a headpond for the night, and a hall that gives the power a job. This page puts them on the same ridge.
Not an engineered plant. Not a site. Not affiliated with ILI Group, and not The Stoics, Balliemeanoch, or Loch na Cathrach. Those names appear later only as published scale anchors. Shaft figures are carried over from the Shaft Apex concept, which was already a sizing study.
Three layers. Switch them in the day model. Salt is the Shaft Apex heat store. The loch is new on this ridge. The hall is the load that makes storage mean something.
From Shaft Apex
Four identical yawing collectors in a square. The crown tracks azimuth. Segmented mirrors, then a CPC, then a spectral split: multi-junction cells take the electric band, and infrared goes to molten salt near 565 / 290 °C or a hot-rock bed near 600 °C. One shared power block. Paper nameplate 2.0–2.5 GW, paper year 8–10 TWh, store 40–60 GWh electric-equivalent. Wind, yaw, and cost at three kilometres still have no precedent.
Highland pumped storage, resized
Upper pond 25 million m³, gross head 500 m, machines at 1 GW. Deliverable store 27.3 GWh — about 27.3 hours at full gate — with round trip taken as 80%. That is smaller than the reported Balliemeanoch scheme (1.5 GW, 45 GWh, 58 million m³ at Loch Awe) and it is not that scheme.
A hall sized to one estate
Compute you can set from 0 to 600 MW. Almost all of that electricity comes back as low-grade heat; the study keeps 70% of it and counts eight dwellings per megawatt, so 300 MW is 2,400 homes on the terrace. The Stoics are a reported 1.5 GW network across three Scottish sites. This page borrows the pairing — firm power, heat reused, a place to live — and not the national total. Batteries stay inside the Shaft Apex fast store; they are not resized into a second pipeline.
The chart asks one question: after the sun drops, does the hall stay up? Stores start at 70%. Shafts offer the paper-day curve, capped at 2.25 GW, and anything above the cap can enter the salt. Surplus after the hall and the export pumps the loch at 80% round trip.
Three dark days, and the hall stays lit. The loch is what the shafts were missing.
The stack is only what met the line. Charging is separate: 0.00 GWh into salt, 0.00 GWh pumped. Lowest stores — loch 15%, salt 9%.
Same estate, four views. The geometry is a picture of the study, not a survey.
Middle column is this page. It inherits the shaft column and sits beside public projects only for scale.
This study2.0–2.5 GW
Shaft ApexSame figure, the source
Public anchorLarge CSP plants are reported under about 1 GW, towers well under 300 m
This study3,000 m · 5–6 million m²
Shaft ApexShaft Apex geometry
Public anchorNo operating plant is in this class
This study40–60 GWh electric-equivalent
Shaft ApexSalt 565 / 290 °C, rock near 600 °C, plus a fast battery
Public anchorTypical CSP tanks are hours, not multi-day
This study1 GW · 27.3 GWh · 25 Mm³ · 500 m
Shaft ApexNone. Shaft Apex has no upper pond.
Public anchorBalliemeanoch is reported at 1.5 GW, 45 GWh, and 58 Mm³ on Loch Awe
This studyNot these schemes
Shaft Apex—
Public anchorLoch na Cathrach, 450 MW, began with ILI and moved to Statkraft. Corrievarkie is reported at 600 MW above Loch Ericht.
This study0–600 MW on one terrace
Shaft ApexNone
Public anchorThe Stoics are reported near 1.5 GW across Fife (Cato), North Lanarkshire (Aurelius), and East Ayrshire (Rufus)
This studyLeft inside the shaft’s fast store
Shaft ApexGrid response, not a second portfolio
Public anchorILI’s public battery list is a multi-gigawatt pipeline of separate sites
Deliverable energy is ρ g V H η. Water at 1,000 kg/m³, g = 9.81, volume 25 million m³, head 500 m, round trip 0.8. That is 27.25 GWh, shown as 27.3. The clear-day shaft curve is scaled so its integral matches the 9 TWh paper year (24.7 GWh in twenty-four hours) and then clipped at 2.25 GW. None of this is a yield study.