Prairie City 2040: write the city’s energy plan

Plan buildings, cars, the industrial park and local supply for 2040 within a budget, site a solar farm, and answer a stakeholder panel in a two-page plan summary

Capstone C3 of Energy Systems, Step by Step: on the City Planner’s engine, plan a fictional city’s buildings, cars, industrial park and local supply for 2040 within a budget, site a solar farm, report cost, CO2, substation peaks and a screening estimate of who pays, and answer a stakeholder panel.
  • Analyst to Modeler · L2–L3
  • Capstone
  • 150 min guided · 60 min lab
  • After SB3 and A18 and A15 and A13 and A19

The brief

Prairie City's council asks for its 2040 energy plan: what to change in buildings, cars, the industrial park and local supply, within $1,500 million of up-front spending.

Also: where a solar farm should go, and who gains and who pays.

  1. Hand in: a plan link and a two-page plan summary. The summary carries the sensitivity table and the panel's reactions, with your answer to each stakeholder who objects; attach the chart as an image where you can.
  2. From: the City Planner's engine, with 2040's plan on 2025's people, homes and prices and the course's synthetic weather (Prairie City is fictional; its numbers are illustrative).
  3. Done when: every check under the summary is in place (the budget, the sensitivity test and an answer to each objection among them), and the self-check reaches Proficient on every competence.

About 150 minutes: 50 to build and test plans, 20 to site the solar farm, 50 to write the summary, 30 to check it.

Modeler version: plus M12's notebook, about 60 minutes: run your plan's district levers in its last section.

Build and test your plan

Control Default plan Range
Furnaces and resistance heat switched to heat pumps 0 % 0 to 100 %, in steps of 5 %
Buildings retrofitted 0 % 0 to 100 %, in steps of 5 %
Dense core's heat from a district network 0 % 0 to 50 %, in steps of 5 %
Network's heat pump 0 MW heat 0 to 250 MW heat, in steps of 10 MW heat
Network's heat store 0 MWh 0 to 2,000 MWh, in steps of 100 MWh
Cars that are electric 1 % 1 to 100 %, in steps of 1 %
EV charging Unmanaged one of: Unmanaged, Managed
Rooftop solar added 0 MW 0 to 400 MW, in steps of 10 MW
Batteries at the substations (4 hours) 0 MW 0 to 200 MW, in steps of 10 MW
Substation upgrades Allowed one of: Allowed, Not allowed
Upgrade cost 800 $/kW 200 to 2,000 $/kW, in steps of 50 $/kW
Heat a retrofit saves 18 % 10 to 50 %, in steps of 1 %
Retrofit cost 9,000 $/home 3,000 to 25,000 $/home, in steps of 500 $/home
Network cost 12,000 $/home 5,000 to 25,000 $/home, in steps of 500 $/home
Who adopts first Every group alike one of: Every group alike, Lower incomes first, Higher incomes first
Shared costs recovered Per kWh one of: Per kWh, Fixed charge, By income
Food plants' heat below 100 °C from heat pumps 0 % 0 to 100 %, in steps of 10 %
Fertilizer plant's hydrogen from electrolysis 0 % 0 to 100 %, in steps of 10 %
Wind contract to the west 0 MW 0 to 400 MW, in steps of 10 MW
Solar farm 0 MW 0 to 150 MW, in steps of 10 MW
Solar farm's site Site A one of: Site A, Site B, Site C, Site D, Site E
Value of a contract MWh 35 $/MWh 20 to 80 $/MWh, in steps of 5 $/MWh

With JavaScript on, you change the plan, run it in your browser and copy a link to it. Without it, write the summary on the reference plan: its evidence is in the results below. Prairie City is fictional; its numbers are illustrative.

Result: 2025 as it is, then the reference plan of the exemplars (70% heat pumps, 40% electric cars, 200 MW of wind, a 100 MW solar farm at A19's site A) Value
2025: up front, 2026 to 2040 (2025 dollars) $0.0M of a $1,500.0M budget
2025: the city's yearly cost against 2025 $0.0M
2025: the city's CO₂ (location-based, operating) 2,765,433 t a year
2025: busiest hour against the limit, core · suburbs · fringe 213/250 · 192/230 · 48/60 MW
2025: energy burden, homes below 80% of area median income (screening) 6.1%
Reference plan: up front, 2026 to 2040 (2025 dollars) $1,227.9M of a $1,500.0M budget
Reference plan: the city's yearly cost against 2025 −$29.2M
Reference plan: the city's CO₂ (location-based, operating) 2,423,488 t a year
Reference plan: busiest hour against the limit, core · suburbs · fringe 250/250 · 256/230 · 60/60 MW
Reference plan: energy burden, homes below 80% of area median income (screening) 5.5%

Precomputed with HiGHS on 6 November 2026. Prairie City is fictional; its numbers are illustrative. With JavaScript on, you run your own plan.

The reference plan's evidence, for the summary without JavaScript

Who pays (screening, accounting layer, not the LP; every group adopting alike):

Household group Home energy bills Energy burden Transport: fuel and charging
0-30% of area median income $1,940 → $1,750 14.9% → 13.5% $1,219 → $903
30-50% of area median income $2,131 → $1,924 6.5% → 5.8% $2,032 → $1,506
50-80% of area median income $2,252 → $2,039 4.2% → 3.8% $2,574 → $1,908
80-100% of area median income $2,417 → $2,192 3.3% → 3.0% $2,845 → $2,109
100% of area median income or more $2,702 → $2,456 1.9% → 1.7% $3,306 → $2,450

Jobs (screening, lesson A13's coefficients): 2,947 construction job-years, 2026 to 2040 (gross), 2,358 net of displacement; ongoing at the farms 18 direct, 29 gross supported, 23 net of displacement.

The panel:

Stakeholder Reaction Why Their rule
City council Yes Within budget: $1,227.9M of $1,500.0M up front. Yes within the budget; no above it.
The electric utility Partly 26 MW of upgrades: work, but doable. Yes up to 20 MW of upgrades; partly up to 60 MW; no above.
Low-income advocates Yes Burden 6.1% → 5.5% (screening). Yes if their burden falls; partly if it rises by under 0.3 points; no above.
Climate group No Down only 12%. Yes for a 35% cut in the city's location-based CO₂ or more; partly from 15%; no below. Contracts do not count in it.
Industrial park Partly Its yearly cost +$2.2M (7%). Yes if its yearly energy and equipment cost does not rise; partly up to 10% more; no above.
Farmers and rural residents Partly 100 MW at site A, 12 km E, 8 km N of the centre, on about 542 acres of farmland. Yes with no farm; partly once a site is chosen on the map; the map's layers decide.

Sensitivity (the plan held fixed):

Input Range tested Yearly cost against 2025 What kind of number
Upgrade cost $200/kW to $2,000/kW −$29.9M to −$27.6M set for teaching
Value of a contract MWh $20/MWh to $80/MWh −$17.6M to −$63.8M set for teaching
Retrofit cost $3,000 a home to $25,000 a home −$33.5M to −$17.7M set for teaching
Network cost $5,000 a home to $25,000 a home −$29.2M to −$29.2M set for teaching
Heat a retrofit saves 10% to 50% −$28.5M to −$31.6M set for teaching
The park's gas price $3.00/Mcf to $7.00/Mcf −$28.3M to −$30.6M set for teaching from EIA prices
All together every cheaper end, then every dearer end −$72.6M to −$2.9M a joint test

The five solar sites (A19's screen, a 100 MW farm; up front: line, road and land, 2025 dollars):

Site Where Line to Up front Capacity factor
A (the plan's) 12 km E, 8 km N of the centre S4, 1.0 km $5.3M 23.8%
B 9 km E, 8 km N of the centre S4, 2.0 km $7.0M 23.7%
C 12 km W, 1 km S of the centre S3, 4.4 km $10.4M 24.1%
D 11 km E, 11 km N of the centre S4, 3.0 km $7.7M 23.6%
E 15 km W, 2 km S of the centre S3, 7.8 km $13.2M 24.1%

Contracts: the city used 771 GWh a year of the farms' 771 GWh; not deducted from the location-based CO₂. A market-based report could claim about 301,316 t for them (simplified: the grid's average rate, no residual mix).

  • Illustrative: Prairie City, its districts, substation limits, industrial park, data-center campus (a load only) and household groups; retrofit, district-heat, upgrade and industrial heat-pump costs, the value of a contract MWh, the budget and the panel's rules are set for teaching.
  • Prices: Kansas 2025 (EIA); the park's gas price set for teaching from EIA's prices.
  • Weather and load: NOAA's Wichita normals on SPP's 2025 hourly shapes (EIA-930), synthetic.
  • CO₂ and households: eGRID's 2023 SPP North rate (EPA); DOE LEAD's income bands.
  • Costs: heat pumps, rooftop solar, wind and solar farms from EIA; batteries from NREL; electrolyzers from DOE; 2025 dollars.
  • The year 2040: 2025's people, homes and prices; only the plan changes. The park and the campus take power at their own substations.
  • The siting map: A19's seeded region around Prairie City: its layers, the five best blocks for a 150 MW solar farm by A19's default weights, a least-cost line to a transmission substation, an access road and the land, in 2025 dollars (illustrative).
  • Who pays and jobs: A13's accounting layer, with its coefficients set for teaching: screening estimates, not predictions.

Write your two-page plan summary

  1. Title and plan link: the plan's link from the bench, and the date
  2. Recommendation: Three or four sentences: what Prairie City should do by 2040, and why.
  3. The plan: each choice, with its unit
  4. Results: each result, with its unit and boundary; the panel's reactions, with your answer to each stakeholder who objects; the sensitivity table
  5. Assumptions: one sentence each
  6. Sensitivity: how one result moves when one input changes, and whether the plan was held fixed
  7. Cost, CO₂ and the grid: Two or three sentences: what the plan costs against the budget, what it cuts, and where the substations need room.
  8. Who pays and who gains: Two or three sentences on the household groups, with the adoption rule you assumed.
  9. The solar farm's site: One or two sentences: which site and why, or why no farm.
  10. Sources and credit: One or two sentences: the data behind your numbers and their licences (EIA, NOAA, EPA and DOE public data; A19's simulated layers), and any conflict of interest.
  11. Limits of this analysis: what the model leaves out
Go deeper · ModelerThe Modeler version: your plan in M12's notebook

Run M12’s notebook (SciPy and HiGHS, about 60 minutes). In its last section, set your plan’s district levers (heat pumps, retrofits, district heat, cars, rooftop solar, batteries) and run it: the notebook prints the busiest hours, upgrades, CO₂ and cost of the three districts. Add those lines to your summary and say where they differ from the page, which also counts the park, the campus and the farms.

Check your summary

Weak summary · Developing

Prairie City should go green with heat pumps and wind [1]. Emissions will fall a lot [2] and everyone will save money [3]. Some people objected but the plan is the best [4].

  1. Falls short: No sizes, no shares, no budget: the council cannot check or cost it.
  2. Falls short: By how much, on what boundary, against which year?
  3. Falls short: Who? The household table is a screening estimate with an adoption rule; name the groups and the numbers.
  4. Falls short: Each objection needs an answer: what you would change, or why you would not.

Strong summary · Proficient

Recommendation: switch 70% of furnaces and resistance heat to heat pumps, retrofit 10% of buildings, make 40% of cars electric with managed charging, add 30 MW of substation batteries, move the food plants' low-temperature heat to heat pumps, and contract 200 MW of wind and a 100 MW solar farm at site A [1]. Budget and cost: $1,227.9M up front against $1,500.0M; the city's yearly cost −$29.2M against 2025 (energy bills plus equipment as yearly payments, 2025 dollars) [2]. CO₂ and the grid: the city's location-based CO₂ 2,423,488 t a year, 12% below 2025 (operating only; the contracts not deducted); 26 MW of substation upgrades, the suburbs the tightest [3]. Who pays (screening): energy burden of homes below 80% of area median income 6.1% → 5.5%, every group adopting alike; the cars' fuel and charging count as transport, outside the burden [4]. Jobs (screening): about 2,947 construction job-years to 2040 (gross), 2,358 net of displacement; at the farms 18 direct ongoing jobs, 29 gross supported, 23 net of displacement [5]. Site: site A, the best of A19's five blocks and the cheapest to connect ($5.3M), at a 23.8% capacity factor [6]. Sensitivity: the yearly cost runs from −$72.6M to −$2.9M with every input at its lower- or higher-cost end; value of a contract MWh moves it most, $20/MWh to $80/MWh; every tested input is set for teaching [7]. Panel: to the electric utility (26 MW of upgrades): I keep them, since with the plan's levers fixed they are the cheapest way to meet the suburbs' busiest hour (its dual equals the upgrade's yearly cost); to the climate group (12% cut): the wind and solar contracts do not lower the location-based CO₂ (a market-based report could claim about 301,316 t); deeper cuts need more heat pumps and retrofits, with $272.1M of the budget left; to the industrial park (+$2.2M a year, 7%): I keep the food plants' heat pumps for the gas they save, and show the park's gas price in the sensitivity table; to farmers and rural residents (site A): it is the screen's best block and the cheapest of the five to connect, $5.3M for its line, road and land, 1.0 km to S4, on about 542 acres [8]. Limits: 2025's people and prices held to 2040, one substation per district, eight representative days of synthetic weather, the household rule an assumption, the map's layers simulated [9].

  1. Works: Every lever with its size: a plan the council can cost and check.
  2. Works: Up front and yearly kept apart, on one boundary.
  3. Works: The cut with its boundary, and where the plan needs grid room.
  4. Works: The rule stated, and the estimate labelled as a screening estimate.
  5. Works: Job-years kept apart from ongoing jobs, gross apart from net.
  6. Works: The site's choice with its evidence from the map.
  7. Works: A range, the input that matters most, and what kind of number each input is.
  8. Works: Each objection answered with a reason or a change, from the run's own numbers.
  9. Works: What the plan leaves out, so the council does not over-read it.
Competence Developing Proficient (the bar for this plan summary) Strong
Consistent accounting
Look for: Cost and CO₂ on one boundary (the whole city, a year, 2025 dollars, location-based); who pays named by household group, as a screening estimate; jobs as construction job-years and ongoing jobs, gross and net.		 Costs and emissions on different boundaries. Cost and emissions on one boundary; emissions question named; who pays and who benefits named. Distributional and environmental side effects estimated with stated assumptions.
Uncertainty
Look for: The sensitivity table: each input one at a time and all together at their cheaper and dearer ends, each input classed as public data or set for teaching.		 Single numbers. Each tested input classed as public data or set for teaching; the one-at-a-time and the joint cheaper and dearer cases reported, the result as a range, and the inputs that could flip the recommendation named. Decision-relevant uncertainty identified and its value discussed.
Realism
Look for: What the plan leaves out: power flow inside districts, 2025's people and prices held to 2040, the household rule an assumption; the site's evidence from A19's simulated layers.		 Assumes announced projects exist. Evidence status of key inputs; a 'what the analysis leaves out' list. Realism checked with a practitioner or primary documents.
Integrity
Look for: The sources field filled; every stakeholder who objects answered fairly, with what you would change or why you would not.		 Licences or credit unchecked. The data's sources and licences named (public data from EIA, NOAA, EPA and DOE; A19's simulated map layers), the numbers called illustrative, any conflict of interest stated, and every stakeholder who objects answered fairly. Data and code released with documentation where allowed.
Communication
Look for: Two pages the council can act on: the recommendation first, then the evidence, the panel and the limits.		 Results without limits. A two-page plan summary with the plan link, the sensitivity table (and the chart as an image, where you can attach one) and an answer to each stakeholder who objects: the recommendation first, then the evidence (budget, cost, CO₂, the substations, who pays, jobs, the site), the panel's objections answered, the sensitivity and the limits. A briefing a decision-maker could act on without misreading.
Go deeper · ResearcherFrom this capstone to your own study

The same plan, panel and summary grow into a research project: frame a question about a city’s heat or its substations, test it with uncertainty, and report it with its limits. The research capstone (CR) and the question studio R10 take it from there.

Numbers, sources and what’s next

Inputs the plan uses

Input Value Source
Substation limits: core · suburbs · fringe 250 · 230 · 60 MW prairie-city.json: each district's 2025 busiest hour × 1.15, rounded up to the next 10 MW (17%, 20% and 25% above it; teaching)
Electricity, Kansas 2025: homes · businesses 14.44¢ · 11.19¢ per kWh Electric Power Annual, Table 2.10: Average Price of Electricity to Ultimate Customers by End-Use Sector, by State, 2025 and 2024 (EIA)
Gas, Kansas 2025: homes · businesses $14.81 · $11.90 per thousand cubic feet Natural Gas Prices, Kansas (annual) (EIA)
Grid CO₂ 862 lb per MWh, plus 5% losses EPA eGRID2023, SPP North
Heat pump COP, an illustrative curve 2.4 at −15 °C; 3.2 at 0 °C; 1 below −23 °C anchored to DOE's cold-climate challenge target, 2.4 at −15 °C (U.S. Department of Energy, 24 Sep 2021); the rest is the course's curve (lesson F3), with resistance backup assumed below −23 °C
Heat pump, per home $7,355, 15 years EIA AEO2026, residential (2022 dollars, converted)
Rooftop solar $4,738 per kW, 25 years EIA AEO2026, residential (2022 dollars, converted)
Battery, 4 hours $1,371 per kW, 15 years NREL 2025 update (2024 dollars, converted)
Retrofit: cost a home · heat saved · life $9,000 · 18% · 30 years set for teaching (illustrative): the defaults, which you change on the bench
Heat network: per home-equivalent · plant heat pump · heat store $12,000 (40 years) · $1,200 per kW of heat, COP 3 (25 years) · $3,000 per MWh (30 years) set for teaching (illustrative); 10% of the heat lost in the pipes; the gas boiler (90%) is assumed to exist already: its fuel is counted, not its construction
Substation upgrade $800 per kW, 40 years set for teaching (illustrative): the defaults, which you change on the bench
Managed charging any hours of the same day, at most a sixth of the day's charge in one hour set for teaching: cars plugged in at home or work whenever needed (an upper bound on what managed charging can do)
Yearly payments 4% real, over each item's life lesson 13's rate (NLR ATB 2025)
Gas, the industrial park $4.55 per thousand cubic feet set for teaching from EIA: Kansas's 2025 citygate price ($5.52) × its 2024 ratio of industrial to citygate price (4.29 / 5.23); EIA publishes no 2025 Kansas industrial price
Wind farm · solar farm $1,712 · $1,484 per kW, 30 years EIA AEO2026, electricity (2025 dollars; via lesson 13)
Electrolyzer $2,186 per kW, 30 years; 57.5 kWh per kg DOE Record 24005 (2022 dollars, converted)
Industrial heat pump · value of a contract MWh $900 per kW of heat · $35/MWh set for teaching (illustrative)
Budget, up front 2026 to 2040 $1,500 million set for teaching (illustrative)

Keep going

Back to the course map

Related lab: M12's notebook: Prairie City's energy hub in SciPy and HiGHS, about 60 minutes.

Built on

  • The City Planner (the engine), M12 (its linear program) and A17 (what a substation's limit stands for).
  • Open tools for city plans: PyPSA, Pyomo and, for siting, QGIS.

Sources and further reading

Spotted an error, or stuck? Write to hlli@ksu.edu. Corrections are made in place and dated here.

Text licensed CC BY 4.0, code MIT: teachers and students may reuse and adapt it, with credit to Honglin Li.