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Holyoke plantSublime Systems—

Holyoke plant

by Sublime SystemsUS

PilotStage 3 of 5

Paused since December 2025 after losing federal funding.

Updated Dec 2025Checked 25 Sep0 updates this week

Milestones

No announced next step
  1. Pilot plant in Somerville2023Complete.
  2. DOE $87M award selectedMar 2024Complete.
  3. DOE award cancelled30 May 2025Complete.
  4. Holyoke plant pausedDec 2025Complete.
  5. Holyoke construction and start-upMissedMissed.

Most important updates

  • Dec 2025
  • 30 May 2025

Current obstacles

  • Electricity costThe process swaps fuel for electricity, so cheap clean power is key to competing on price.

Physics limits

  • Chemistry sets an energy floorFreeing calcium from rock takes the same chemical energy a kiln supplies as heat; electricity is cleaner but usually costs several times more per unit of energy than fuel.
  • Silicate rocks dissolve slowlyCalcium silicates are very stable minerals: they dissolve slowly and leave silica gel behind, which makes reactors larger and separation harder.

How it works

3 parts
A water electrolyser at London's Science Museum: Sublime's cells likewise use electricity to split water, making acid at one side and base at the other
A water electrolyser at London's Science Museum: Sublime's cells likewise use electricity to split water, making acid at one side and base at the otherPhoto: The wub · CC BY-SA 4.0 (opens commons.wikimedia.org)
Electrolyser

Electricity makes acid and base

An electrolyser splits water into an acid stream and a base stream at near room temperature, replacing the fossil-fired kiln.

Calcium

Acid frees calcium from rock

The acid dissolves calcium-bearing rock; the base then precipitates the calcium as calcium hydroxide.

Cement

Binder made without a kiln

The calcium hydroxide is combined with silica to form cement's binding compounds, sold against a performance standard.

Spec sheet

SpecHolyoke plant
Planned capacityUp to 30,000 t/yrR (reported)

R reported by the company

Update log

2 updates

Dec 2025

  • Major: PressPeople

Fri 30 May 2025

  • Major: PressRegulatory

About Sublime Systems

The team behind Holyoke plant

Sublime Systems

Electrochemical, kiln-free cement

Sublime Systems (founded 2020 by Leah Ellis and MIT's Yet-Ming Chiang) makes cement with electricity at room temperature not in a fossil-fired kiln. Its Holyoke, Massachusetts, plant was paused in late 2025 after the US government cancelled an $87M award.

  • Uses electricity to pull calcium from rock without burning limestone, avoiding both fuel and rock CO2.
  • DOE cancelled its $87M award in May 2025; Holyoke was paused in December 2025 and about two-thirds of staff were later cut.
  • Signed a deal in 2025 for Microsoft to buy its cement.

sublime-systems.com (opens sublime-systems.com)Company profile →

Founded
20206 yrs
Headquarters
United States
Status
Private
Valuation
private
Works in
MaterialsClean cement
Coverage
1 program · 2 updateslatest 1 Dec 2025checked 25 Sep
Customers
Microsoft (opens sublime-systems.com)
People
Leah EllisCo-founder & CEOYet-Ming ChiangCo-founder
Primer