Greg Wilk

Turning down a Jane Street offer for @fuseenergy, for less than a quarter of the pay, was the FIRST real decision of my life.

Until then, I’d been an automaton: best school I could get into, job that paid most.

But I wanted to build something from nothing (apparently office chairs included 🪑).

Fuse had about 20 people, and I believed in @alanchanguk and @charlesorr, who’d helped build Revolut. Having done it before is the best predictor of winning again.

I’d accepted a remote role but practically moved into the office for full immersion, working every day to help get Fuse off the ground. Now I lead engineering here.

Seeing us on a billboard makes me glad I went all in with them.

I got to be the ambitious kid because of my mom.

She drove me to swimming, guitar and English lessons. I slept through most of it in the back of her car.

Last week she drove me to the airport, the first stretch of the 1,449 km back to London, where I get to work on energy abundance.

Thank you, Mom. You backed me before I knew who I wanted to be.

Thiel’s right. Regulation pushed a generation of engineers out of atoms and into software.

But walls that keep everyone out are now an opportunity.

A researcher I interviewed recently asked: what if regulation walls you in like everyone else?

Energy is a walled garden. The walls are a licence, months of industry testing before you can switch a single customer, and enough collateral to buy power long before anyone pays you for it.

Inside, the garden never runs dry. A country can’t function without energy, so supplying it has to stay profitable.

So for decades, the fat kid has sat in there eating the fruit. Nobody’s made him run.

We got over the wall in 2023, with engineers from trading firms. Three years later:
1. We supply over 450,000 homes, with operating costs already 17% below other suppliers.
2. A few weeks ago we started training our own transformer. It already forecasts tomorrow’s demand off by 1% on average. Our previous classical ML model missed by 3.5%.
3. So now we know what our customers will use. With Jules, our plug-in battery and solar system, our trading desk will decide when each home draws from the grid, co-optimised against live power prices.

The rules that kept engineers out of energy also kept the fat kid from ever having to compete. Now we’re over the wall, our costs keep falling, and we’re coming for his lunch.

The biggest mistake I've seen CTOs make is handing exceptional engineers ordinary problems, people and process. That's how those engineers leave.

How I avoid it at Fuse:

Problems
The ambition has to be big enough. We’ll have the fastest (energy supplier) expansion the world has ever seen. We’ll print countries: a product factory where tokens go in and new energy markets come out. Energy abundance. And our own inference powered by it.

People
I've spent 794 hours interviewing engineers for Fuse. I hold the bar high on every engineer. Mediocre can't slip through.

Process
In 2023 four backend engineers were split across Python and Kotlin repos. The system was split before anyone knew where the interfaces were. So I deleted Kotlin from the backend.

Remove friction to build.

1. Today, all of Fuse is one monorepo, so one engineer cuts across the whole system in one PR.

2. Our AI reviewer already approves some kinds of PR on its own, and we'll do 80% by year end. Additionally, humans will review what a change should do, not every line.

If your team grows linearly with your workload, you’re failing.

August 2022, three weeks before I joined Fuse, I finished Google’s SRE book. One line stuck: “…the number of SREs needed… scales sublinearly with the size of the system.”

Customer support is a system.

January: 30,047 chats. A person answered every one.
October: 157,554 chats. A person answered 30,565.
Our own GPUs took care of the rest. 24 billion tokens last month.

Code review is a system.

We’re letting our AI reviewer approve PRs on its own, rolling it out one kind of PR at a time. Every PR passes the basics: review comments fixed, reviewer untouched, etc. Then its kind’s own checks: a bug fix needs a test that fails without it, no weakened tests, etc.

Sublinear.