What does a city run on, and who controls what?

Follow Prairie City’s year of energy from its sources to its sectors, then see who decides each part

F9 of Energy Systems, Step by Step: follow a fictional U.S. city’s year of energy from gas, fuels, the regional grid and rooftop solar to its homes, shops, transport, industry and a data-center campus; then sort who typically decides each lever, from utility rates to building codes and equipment standards.
  • Foundations · L1
  • 15 min guided · about 10 min practice
  • After F3 and F6

Prairie City's year of energy, 2025, in GWh (1 GWh = 1 million kWh)

Prairie City is fictional; its numbers are illustrative.

Sector Takes in Useful energy Counted as lost
Buildings: homes, shops, offices and public buildings 3,994 GWh 3,586 GWh 408 GWh (10%)
Transport: cars, buses and trucks 3,517 GWh 1,059 GWh 2,458 GWh (70%)
Industry and farms (the industrial park, the farms) 1,481 GWh 552 GWh (and 591 GWh of hydrogen) 338 GWh (23%)
Data-center campus, one large load kept apart 1,076 GWh 1,076 GWh not estimated (its electricity counts as useful)

Convention: for computers, appliances and lights, the electricity delivered counts as useful; their own losses are not estimated, so a sector's loss share is not its efficiency.

  • Carriers. Electricity 3,477 GWh; Gasoline 3,167 GWh; Natural gas 2,859 GWh; Diesel 444 GWh; Propane 125 GWh.
  • Electricity. Rooftop solar makes 0.9% of it; the rest comes from the SPP grid, and 166 GWh is lost in the city's wires.

Who decides, for a Kansas city served by an investor-owned utility (typical roles)

Lever Usually decided by
The price per kWh a home pays its investor-owned electric utility The state regulator
Which power plants and contracts supply the city's electricity The utility
The substations and feeders that serve each street The utility
Rules for interstate transmission and wholesale power sales Federal rules
The least efficiency a new furnace, water heater or light bulb may have Federal rules
Safety rules for the gas mains under the streets Federal rules
The energy code new buildings in Prairie City must meet The city
A permit to put solar panels on a roof The city
Whether a home swaps its furnace for a heat pump Owners

With JavaScript on, you follow the flows step by step, sort who decides each lever, and light up each actor's part of the flows.

  • Illustrative. Prairie City is fictional; its numbers are illustrative, and its flows are built bottom-up from its homes, vehicles, industrial park and data-center campus in the course's shared city data.
  • Anchored. Fuels at their energy content (EIA); engine and EV efficiencies from DOE; the grid's hourly shapes from SPP's 2025 data.
  • Who decides. Roles for a Kansas city served by an investor-owned utility: typical, not universal, each from a dated primary source listed under Sources.

Need a refresher? F3 on carriers, services and useful energy; F6 on how power reaches a plug.

What you just did, as diagrams

Carriers to sectors
A city buys gas, fuels and electricity, and uses them in buildings, transport and industry; buildings take the most, 3,994 GWh.
Useful and lost
Engines lose most of their fuel as heat: transport turns 30% of what it takes in into motion.
A convention
For computers, appliances and lights, the electricity delivered counts as useful; their own losses are not estimated, so a sector's loss share is not its efficiency.
The power sector
Prairie City makes 0.9% of its electricity; its accounting starts where the regional grid's power enters its wires.
Who decides
For a Kansas city served by an investor-owned utility, the state regulator approves rates, federal rules set equipment standards and interstate markets, the city adopts its energy code and issues permits, and owners choose equipment.
Typical, not universal
A city that owns its utility sets its own rates; many states adopt one energy code for the whole state, and states organise their utilities differently.
Go deeper · AnalystWhere a city's count starts
  • Final energy is what the city buys at the meter or the pump; useful energy is the warmth, motion and light it gets.
  • A convention. For appliances, lights and computers the electricity delivered counts as useful, so their own losses are not estimated; for heat and vehicles, the heat or motion delivered counts.
  • The boundary. Power plants on the regional grid are outside the city: their losses appear in a regional or national count, not here.
Go deeper · AnalystWho decides, in a little more detail
  • Rates. An investor-owned utility asks its state commission to change rates; the commission reviews its costs and approves the rates and terms.
  • Supply. In states without retail competition, as in Kansas, utilities may build, own and run power plants; states with retail competition leave generation to competing suppliers.
  • The grid. A regional operator such as SPP runs the bulk grid and the wholesale market under FERC’s rules.
  • Codes. The U.S. has no national energy code: states or local governments adopt one, and local permit offices enforce it.
Go deeperWhat this lesson leaves out
  • Emissions from each flow, and how a city counts them.
  • Hours and seasons: a year's flows hide the coldest evening.
  • Costs and who pays them.
  • Rules outside the U.S., and the details of any one state's law.

Check yourself

Practice, about 10 minutes: three myths, then four questions.

Myth or fact? “Prairie City's council alone decides which power plants make its electricity.”

  • Myth
  • Fact
Answer

Myth. In Kansas the utility picks its plants and contracts, the state regulator reviews their costs and SPP runs the regional grid; the city shapes its own use, buildings and permits.

Myth or fact? “The city council sets the electricity rate every home pays.”

  • Myth
  • Fact
Answer

Myth for an investor-owned utility: in Kansas, the state's commission approves the rates. Fact where the city owns its utility.

Myth or fact? “Most of the energy a car burns moves the car.”

  • Myth
  • Fact
Answer

Myth. Prairie City's transport takes in 3,517 GWh and turns 1,059 GWh into motion; the rest leaves as heat.

Prairie City's homes buy 1,155 GWh of electricity, 1,376 GWh of gas and 99 GWh of propane; their heat pumps also draw 138 GWh of free outdoor-air heat. About what share of what they buy is gas?

  • A quarter
  • Half
  • Three quarters
Answer

About half of what they buy: 1,376.2 ÷ 2,630.0 = 52%; counting the free outdoor-air heat too, 1,376.2 ÷ 2,767.7 = 50%.

Who approves the rates of Kansas's investor-owned electric utilities?

  • The city council
  • FERC
  • The Kansas Corporation Commission
Answer

The Kansas Corporation Commission, the state regulator; FERC regulates interstate transmission and wholesale sales.

Which body regulates interstate transmission and wholesale power sales?

  • FERC
  • The state regulator
  • The utility
Answer

FERC, the Federal Energy Regulatory Commission.

Prairie City's meters take 3,311.5 GWh of electricity a year, and the wires lose 5% as much again (set for teaching). How much is lost?

  • About 17 GWh
  • About 166 GWh
  • About 1,656 GWh
Answer

3,311.5 × 0.05 = 165.6 GWh, about the flow to distribution losses in the Sankey.

Numbers, sources and what’s next

Numbers to remember

Number What it means Source
3 of every 4 U.S. electricity customers served by investor-owned utilities (72% in 2017); 1,958 publicly owned utilities served about 12,100 customers each on average. EIA, Today in Energy · 15 August 2019; data for 2017
75% · 40% Shares of U.S. electricity and of total energy that buildings use. DOE Building Technologies Office, Data and Analysis for Buildings Sector Innovation · page read 6 November 2026
more than 70 Kinds of appliances and equipment with DOE efficiency standards, about 90% of home energy use. DOE, Appliance and Equipment Standards Program · page read 6 November 2026
17 states The Southwest Power Pool, the regional grid operator for Kansas, serves members in all or part of 17 states. SPP, Fast Facts · updated October 2026

Keep going

Back to the course map

Sources and further reading

Who decides what (typical U.S. practice):

  • U.S. Department of Energy, Office of Electricity Delivery and Energy Reliability. United States Electricity Industry Primer (DOE/OE-0017). July 2015. §4.5, p. 27: state commissions regulate what are fair and reasonable rates; §4.6, p. 27: public power is generally regulated by its own local government; §4.8, p. 30: where utilities are vertically integrated, they may construct, own and operate power plants.
  • Kansas Corporation Commission. The Commission's Role. Undated; read 6 November 2026. The Utilities Division establishes and regulates rates for public utilities; the KCC does not regulate most electric cooperatives or municipalities.
  • Kansas Corporation Commission staff. Rate Study of Kansas City Power & Light and Westar Energy for the years 2008 to 2018. December 2018; read 6 November 2026. P. 2: each electric utility builds an integrated system to generate, transmit and distribute electricity in its service territory.
  • U.S. Energy Information Administration, Today in Energy. Investor-owned utilities served 72% of U.S. electricity customers in 2017. 15 August 2019; data for 2017. Three out of every four utility customers; 1,958 publicly owned utilities averaging 12,100 customers; 812 co-ops averaging 24,500.
  • U.S. Energy Information Administration, Electricity explained. How electricity is delivered to consumers. Undated; read 6 November 2026. Local electric utilities operate the distribution system that connects homes and businesses to the grid; utilities plan for future power needs.
  • Federal Energy Regulatory Commission. What FERC Does. Updated 18 June 2025. Regulates the transmission and wholesale sale of electricity in interstate commerce, and interstate natural gas pipelines; does not regulate retail sales to consumers.
  • U.S. Department of Energy. Appliance and Equipment Standards Program. Undated; read 6 November 2026. More than 70 products, about 90% of home energy use.
  • U.S. Department of Transportation, Pipeline and Hazardous Materials Safety Administration. State Effort. Updated 15 May 2026. PHMSA develops pipeline safety regulations; certified state agencies inspect intrastate pipelines, including most gas distribution systems.
  • U.S. Department of Energy. Energy Codes 101: What Are They and What is DOE's Role?. 31 May 2016. No national energy code; states or local governments adopt codes; enforcement is almost always by local permit offices.
  • U.S. Department of Energy, Building Energy Codes Program. Kansas: current energy code status. Undated; read 6 November 2026. Residential and commercial: home rule, enforced by local jurisdictions.
  • U.S. Department of Energy. 160 Communities Now Automating Solar Permitting with SolarAPP+. 20 December 2023. Jurisdictions issue permits for residential rooftop solar.
  • U.S. Department of Energy. Energy Saver: Tips on Saving Money and Energy in Your Home. 2022. Heating and cooling choices for homeowners, heat pumps on p. 16.
  • U.S. Department of Transportation. Corporate Average Fuel Economy (CAFE) Standards (no link). Updated 11 August 2014. NHTSA sets and enforces the CAFE standards.
  • Southwest Power Pool. About Us. Undated; read 6 November 2026. A regional transmission organization mandated by FERC to ensure reliable supplies of power, adequate transmission and competitive wholesale prices.
  • U.S. Energy Information Administration. Use of energy explained: Energy use in industry. Undated; read 6 November 2026. Industry's activities include manufacturing, agriculture (farming, fishing and forestry), mining and construction.

Prairie City's flows (the course's shared city data), the parts used here:

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.