Brick heat stores that charge at midday and give small factories steam all night
TL;DR Emberbank puts electrically heated brick stores next to small factory boilers. They soak up cheap solar-hour power during the day and hand back steam or hot air through the night. The factory pays per tonne of steam, not for the kit, and keeps its old boiler as backup.
Plenty of Indian process plants, from dairies to textile dyeing units, need heat round the clock and burn coal, wood or oil to get it. Cheap clean power, meanwhile, shows up in one midday block.
Since April 2024 commercial and industrial users pay 10–20% less in the state-set solar hours and 10–20% more at peak[1]. Since 2022 a plant with 100 kW of demand can also buy green power through open access, and any surplus has to be banked[2]. So what does a factory running night shifts do with midday power? Nothing, unless it has somewhere to keep the heat.
We couldn't find a public figure for India's small-factory heat demand, and that is a gap you'll have to fill before you raise money.
What it does, in regulatory terms: electrical heating equipment that produces steam or hot air. The electrical side follows normal factory wiring rules. The steam side may fall under state boiler inspection, so check with the inspectorate before the first install.
The seed pitched thermochemical storage, which keeps heat in chemical reactions. That's still lab science - a 2020 study tested samples of about 10 mg and found the material still short of the conversion needed to compete with molten salt[3]. So we switched to plain sensible heat in brick, which firms abroad already sell. One overseas maker heats refractory brick to 1100–1500°C, charges for 6–8 hours and discharges for 24[4].
Emberbank's unit is sized for one factory boiler house. Resistive heaters warm a brick stack in solar hours and a fan pushes air through it to a heat exchanger that makes steam on demand. A controller reads the tariff and the plant's steam load and charges only what tomorrow needs. The factory pays per tonne of steam, priced below what its fuel costs today.
The factory owner or plant head pays, and they'll hold your price up against the coal, briquette or oil bill. Charging per tonne of steam takes away the upfront cost that small firms just can't fund.
Start with food processors whose export buyers are asking for lower emissions, since they have a second reason to switch. There's no public price for steam-as-a-service in India, so you'll be quoting off each plant's own fuel bill.
Time-of-day tariffs gave you a dependable midday price dip from April 2024[1]. Open-access rules have let 100 kW plants buy green power since 2022[2]. Abroad, the tech has moved past pilots into big units - one US maker announced a 5 GWh project with a big biofuel producer[5], and a Finnish firm runs sand stores for Finnish heat networks[6].
We found no public figure for small-factory steam demand or boiler fuel spend in India. The signal is indirect. One overseas storage maker lists food and beverage, chemicals and paper among its target industries[5], and India has big clusters of all three.
If you want a real number then count the boilers and fuel spend in one cluster before you fund a pilot.
Overseas startups sell thermal storage in brick[4], carbon blocks[5] and sand[6], but they're sized for large plants or heat networks. We found no Indian company selling packaged electric heat storage to small factories, though our search was limited. Indian boiler makers sell fuel-fired and electric boilers and stop there.
The gap is a unit small enough for a 2–5 tonne-per-hour boiler house, sold as a service.
| Difficulty | Hard (67/100) |
| Starting capital | ₹3–6 Cr |
| Time to launch | 18–24 months |
This is real hardware at very high temperatures, and safety is not optional. The first unit will take a year to design, build and certify. Financing is the second wall, because selling steam means the equipment sits on your balance sheet and not the customer's. Each site also needs a grid connection big enough to charge fast.
Yes. This is high-temperature equipment making steam inside a factory, so safety approvals come before anything else.
Building this outside India? The categories above usually have a local equivalent, so check with your own regulator.
Don't trust AI with safety interlocks. Temperature limits and trips must be hard-wired and certified, whatever the software says.
Want to work out the AI layer for Emberbank? Talk to Yash →
Here's what can go south -
I'd only back this with a founding team that has thermal engineering and boiler experience, plus patient money behind it. Software founders, honestly, should skip it.
Prove one number first - the delivered cost per tonne of steam at one real plant, against its current fuel bill, using real tariff data.
Plan for roughly ₹3–6 Cr, because you design, build and certify real hardware and often own the units at customer sites.
If the unit makes steam under pressure, the state boiler inspectorate may need to approve it, and charging needs a larger load sanction. Confirm both in writing before you build.
Yes, firms abroad already sell this kind of storage. Pressure equipment and grid connection rules differ, so check with your local regulator.
The free Emberbank validation kit has the line-by-line capital breakdown, the effort scoring, the electrical and boiler checklist, a 14-day validation sprint with pass/fail targets, a 90-day launch plan, 10 interview questions for plant heads, and 5 assumptions to test. Download the kit →
Thinking about building Emberbank or something close to it? The make-or-break work is a steam cost per tonne that beats the plant's fuel bill and a first unit that inspectors pass, and that's the kind of thing I help founders with. If you need a hand, you know where to find me. Talk to Yash →
For illustration only. Names are fictional and ideas hypothetical; sourced facts are real but may be out of date. Nothing here is legal, financial or professional advice, and Yash Khatri is not personally liable for any use of it. Read the full disclaimer.