All work

Issue #001 Emberlith

Plant managers can price their own switch off gas, then check the machine on a datasheet drawn to scale.

Concept project · Launch Site · 2026

See it live
The Emberlith home page on desktop: the headline Store the sun in brick. Burn nothing. beside a live section through a brick heat store, with white-hot heating rods, a temperature profile and a readout underneath showing 14:30, charging on solar with steam on, 82% stored. (full size, opens in a new tab)
The Emberlith home page on a phone: the headline, a short pitch and two full-width buttons, Book a site assessment and See how it works, with the top of the brick core and its heating rods already in view below them. (full size, opens in a new tab)

The problem

Emberlith is made up. The problem isn't. Hard-tech startups build machines that run at 1,000°C, then launch a site that could be selling anything.

The hero says "innovative solutions for a sustainable future", which could sell yogurt, over a stock photo of wind turbines. The product is a box of hot brick. The buyer runs a plant with a gas bill, and nobody talks to them in tonnes of steam.

So I set myself a brief: make a thermal battery look like a consumer brand, and keep a datasheet an engineer would sign off.

The cast

The buyer
A plant manager with a gas bill, who buys steam by the tonne and heat by the MWh.
The skeptic
The engineer who has to sign off the datasheet.
The hero
Core E1: brick in a steel box, heated to 1,100°C on cheap wind and solar power.
The villain
The gas boiler, and its bill.

The plan

  1. Show the machine. The hero is a live section through the core: the rods glow while it charges, the heat creeps down the brick, and hot air runs down a duct to the steam generator. You see the product before you read a word.
  2. Speak plant manager. They buy steam by the tonne and heat by the MWh, so the calculator, a sample heat bill and the datasheet all use those units.
  3. Look expensive. It's near black, and the colors come from heat, ember red to white. Only hot things glow. The one gradient sits on the brick, the stored-heat meter and "Burn nothing."

The build

One long page, hand-built. HTML, CSS and 47 KB of plain JavaScript. No framework, no images: every visual is canvas, SVG or CSS.

The Emberlith hero on desktop: the headline Store the sun in brick. Burn nothing. on the left, and on the right a section through the core: glowing brick inside a hatched insulation band and a steel shell, four white-hot heating rods hanging from the roof, a temperature profile curving beside it with a dashed charge front, a duct running down to a steam generator, and a readout showing 14:30, charging on solar with steam on, 82% stored, 890°C. (full size, opens in a new tab)
The hero. The core charges and drains all day, on a loop.
The Emberlith home page on a 390 pixel wide phone: the headline, the pitch, a full-width orange Book a site assessment button and a See how it works button, with the top of the brick core and its heating rods already in view below them. (full size, opens in a new tab)
On a phone, the core reaches the first screen.

The core is 67 to 175 bricks on a canvas, depending on the screen, each colored by the temperature at its height. The same temperatures are drawn beside the stack as a curve, and the dashed charge front sits where it crosses 650°C, so the bend in the curve and the change in the brick line up. Steam runs from the generator into the readout's "Steam out" at 12 t/h, all day, charging or not.

It runs at 30 frames a second, and a frame's code takes about 0.3 ms, or 1.4 ms with the CPU slowed down four times. It stops when it scrolls away or the tab hides. On first load it starts up: the rods switch on one by one and the heat sweeps down to mid-afternoon before the clock starts. Reduced motion gets one still frame.

Four views of the same core through a simulated day. At 03:00 it is charging on night wind, 44% stored, with white-hot rods. At 09:00 it is delivering steam from store, 35% stored, rods dark, the heat only in the top third. At 14:30 it is charging on solar, 82% stored, nearly all the brick glowing. At 20:00 it is delivering steam from store, 61% stored. Steam out reads 12.0 tonnes an hour in all four. (full size, opens in a new tab)
One core, four times of day. The rods only glow while it charges. The steam never changes.
A day on the grid, under the headline At one in the afternoon, the grid pays you to take its power. Three lanes share one timeline: the power price swings between about minus 6 and 169 euros per MWh, with two shaded charging windows marked by an amber rule; heat in store climbs in those windows and falls slowly between them; steam to the plant is a flat line at 12 tonnes an hour. The scrubber is paused at 13:00, where the price is minus 6 euros and the core is paid to charge. (full size, opens in a new tab)
One made-up day drives the chart and the hero. Scrub it with a mouse, a finger or the arrow keys.

On a phone the chart, the calculator and the drawing run edge to edge. A sideways drag scrubs the day, a tap on a line of the key lights its callout, and the drawing sets its dimensions bigger and drops the title block it has no room for. Turned on its side, the phone gets the desktop's cover: the headline beside the core.

The calculator: sliders set to 18 tonnes of steam an hour, 7,200 running hours and 45 euros per MWh of gas give an illustrative saving of 408 thousand to 1 million euros a year, 90,700 MWh of gas and 18,140 tonnes of CO2 avoided, and two Core E1 units. Six assumptions are listed underneath. (full size, opens in a new tab)
The calculator shows its working, right under the answer.

The brick joints in the drawing are one SVG pattern, projected onto each face. That keeps the whole drawing, sheet and title block included, to 12 KB.

The Core E1 datasheet: an isometric cutaway of the steel vessel on a drawing sheet with zone marks and a title block, the brick stack exposed with heating rods running through it, dimension lines for 9.6 and 7.4 metres, a small 1.8 metre figure by the steam generator, seven numbered callouts and a key, next to tables of output, storage and charging specs. (full size, opens in a new tab)
A script draws the cutaway from the datasheet's own dimensions, so they can't disagree. The figure by the steam generator is 1.8 m tall.
  • Kiln#0C0907The warm black everything sits on
  • Ember#C42D0CThe coolest glow
  • Flame#FF7A1FHeat, and the main button
  • Amber#FFB35CLabels and focus rings
  • White heat#FFE8C4Readouts and results
Lighthouse performance, desktop
100
Lighthouse performance, mobile
99
Whole page, gzipped, fonts included
108 KB
Layout shift
0
The first screen gets its own small stylesheet; everything below the fold loads without blocking it. Measured with Lighthouse 12.8 on a plain local server with no compression. Desktop scored 100 in all three runs; mobile scored 99 in four runs out of five and 98 in the other. Accessibility and best practices: 100 on both. Turn gzip on and mobile scores 100, with the main text painted in 1.7 s on a throttled 4G phone.

Go poke around

  • Scrub the day on the grid chart, or press play.
  • Put your own plant's numbers into the calculator.
  • Point at a line of the datasheet's key to light its callout.
See Emberlith live

heyim.london/demos/emberlith/

Before / after

From "innovative solutions for a sustainable future" to "Store the sun in brick. Burn nothing."

Before
The made-up old Emberlith site: a teal and green template with a crowded eight-item menu, a stock photo carousel of wind turbines, the headline Innovative Thermal Energy Storage Solutions for a Sustainable Future, three buttons, a chat bubble and a cookie banner. (full size, opens in a new tab)
After
The new Emberlith home page: Store the sun in brick. Burn nothing. next to a live section through the brick core, and one orange Book a site assessment button. (full size, opens in a new tab)

Next issue

Issue #002 Lullops

A 3am outage, fixed on the first screen. Lighthouse 100 on desktop, 32 KB of JavaScript.

Read the case study

The Lullops home page in its dark theme: the headline Sleep through the night beside a short pitch, and below it a product window replaying a 3am incident with the bad deploy outlined in red.
The Lullops home page on a phone: the headline, the pitch, two buttons and the top of the incident replay, with the bad deploy flagged in red.

Your startup, next issue?

Send a brief. I reply within 24 hours with a plan and a price.

Start a project
All work