How to use the Capacity Expansion Planner
Describe a growing demand and what could meet it, then read which plants and batteries to build, how big, and in which year. Every clip on this page is the real tool, recorded while it was used.
The short version
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Describe the demand
The peak now and how fast it grows, the climate and the shape of a day, and the years to plan.
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Set the supply and the rules
What is in service and when it retires, what can be built at what cost, then a carbon price, a net-zero year and the discount rate.
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Run and read
Press Run plan. The answer says what to build first and when; the charts follow capacity, energy and cost year by year.
Nothing is uploaded. The plan is built by PSA.js, a JavaScript port of PyPSA, and solved by HiGHS, both in your browser.
The screen
Inputs on the left, the answer beside them, the charts and tables under it. Point at a part in the list to see where it is.
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Inputs
Quick Start, save and open, then four tabs: Demand, Supply, Policy and Assumptions. Run plan sits at the bottom. The chevrons fold the card to a slim Inputs rail.
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The answer
What to build first and when, in a sentence, then four figures: new capacity, present cost, LCOE and the clean share of energy.
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The charts
Capacity and when to build, Energy by source with a decision year's typical days under it, and Cost by year. Then the tables and What this assumes.
Top right, Tour replays a one minute walk through the tool, and Guide opens this page.
Quick Start
Four worked plans: a Growing grid whose coal closes, the same grid to Net zero, a Coal exit on a winter-peaking grid, and a tropical Island on diesel. One click replaces the whole plan and runs it.
On a phone, press Full screen under a clip and turn the phone sideways to read it.
Open the inputs
On a first visit the card is folded to a rail, so the answer has the room. Click Inputs to open it; it stays the way you leave it.
Pick an example
Hover a button to read what it holds. A click loads it and solves it.
- Then make it yours. Change anything over the top of an example and run it again.
Demand
How much power is needed now, how it grows, and how it moves through a day and a year.
Peak and growth
The highest hour of demand in the first year, and how much it grows each year, compounded.
Climate and profile
The Climate sets the seasons, in either hemisphere. The Profile shapes a day; drag its bars to draw your own.
Planning years
The first and last year, and how often the plan may build. Each decision year stands for the years up to the next.
- The first year is also the price year. Every cost you enter and every result is at its prices.
- Your own hours. Custom takes the profile from a CSV or Excel file: typical days, by season if you like, or a full year.
- Daily variability. Lets a weekday differ from the weekend, or each day from the next.
Supply
One card per technology: what is in service and when it retires, and whether more can be built and at what cost.
In service and to build
Each card's line sums it up: 700 MW to 2036, new at $1,000/kW.
Open a technology
Its existing capacity and retirement year, whether it can build more, its capital cost, and how it runs: a profile and capacity factor for solar and wind, a running cost and emissions for a firm plant.
Detailed
Adds fixed O&M, lifetime, cost change a year, earliest year, a cap on what may be in service, unit sizes and availability.
Add a technology
+ Add technology offers solar, wind, gas, coal, nuclear, geothermal, diesel, batteries and pumped hydro, with typical costs to start from.
- Duplicate or remove. The icons on each card's head.
- Unit sizes make the plan build in whole units, a mixed-integer problem that takes longer to solve.
Policy and run
Reliability and emissions, then Run plan to see what they change.
Reliability
Whether demand may go unserved, at the value of lost load, when that is cheaper than building for it.
Carbon price
Paid on every tonne a plant emits, in the first year, and how fast it grows.
Net-zero year
From this decision year on, no plant may emit CO2.
Run the plan
Run plan, or Ctrl Enter. Until you do, the last result stays, faded.
Assumptions
The guesses every plan rests on, and how each year is sampled.
Discount rate
Real, above inflation, or Nominal with inflation, from which the real rate is worked out.
Typical days
Each year runs over typical days, one or more a season, set by the profiles. A still, overcast peak day makes the plan hold firm capacity for the worst case.
Solver
A time limit for HiGHS, and with unit sizes an optimality gap.
The answer and the charts
The answer comes first, in words; the charts show how it gets there, year by year.
The answer
What to build first and when, the year that builds the most, what retires, and the present cost and LCOE at first-year prices.
Capacity and when to build
What is in service each year, hatched for the plants there now, with each decision year's new build on top. Decision years are in bold.
Click a year
Opens Typical days for that year: each hour's dispatch, the battery's charging and any curtailment.
Energy and cost
Where each year's energy comes from, and what each year costs: capital, fixed and running, with the levelised cost on top.
- Hover any chart to read a year or an hour; ⟳ resets its zoom.
Results by year
The figures behind the charts, a row per year.
Open the tables
Results by year opens from its chevron.
Pick a table
Capacity, New build, Energy, Costs or Years. ⬇ CSV saves the one shown.
- What this assumes. The last card lists what the plan rests on: its demand, its rates and its prices.
Shortcuts
- Ctrl Enter run the plan
Ready to plan one?
Open the tool