Electricity
From a turning turbine to a warming kettle: discover the network that keeps supply and demand in balance.
Follow the flow.
Conceptual AC supply route. Dots indicate energy transfer, not electron motion. Real networks branch; distributed generation can reverse local flows. Circuit return paths, protection detail, losses, and parallel routes are simplified. Select a component to inspect it.
Electricity generation
A generator or solar cell converts another form of energy into electrical energy. The grid connects that conversion to useful work elsewhere.
Read the diagram as text
- Electricity generation — A generator or solar cell converts another form of energy into electrical energy. The grid connects that conversion to useful work elsewhere.
- Transformers — Transformers make it practical to connect parts of an AC system that operate at different voltages.
- Transmission networks — High-voltage connections let regions share generation, support one another, and move power over long distances.
- Substations & protection — A substation is a controlled junction where power can be transformed, measured, connected, or safely disconnected by designed equipment.
- Distribution networks — Local feeders, cables, and transformers connect the bulk electricity system to streets, buildings, and smaller generators.
- The appliance & its circuit — A kettle, lamp, motor, or computer is a load: equipment that converts electrical energy into another useful form.
Conceptual AC supply route. Dots indicate energy transfer, not electron motion. Real networks branch; distributed generation can reverse local flows. Circuit return paths, protection detail, losses, and parallel routes are simplified.
Electricity makes an everyday action depend on a wide, continuously changing system. Generators, transformers, lines, controls, and appliances work together; some energy is also produced and stored close to the people using it.
Start with a simple supply route, then explore its branches. Our diagrams show functional relationships, not a map of a real grid. Voltage levels, frequency, ownership, fuels, and network designs vary around the world.
Choose your way in.
Switch on a kettle
One small switch. A connected system.
From generation to appliance
A tour of the physical route.
When evening demand rises
What keeps a changing system balanced?
From midday solar to evening light
Follow energy through conversion, storage, and time.
Move a load, change the peak
Explore flexibility without confusing power with energy.
Meet the parts that make it work.
Electricity generation
A generator or solar cell converts another form of energy into electrical energy. The grid connects that conversion to useful work elsewhere.
Transformers
Transformers make it practical to connect parts of an AC system that operate at different voltages.
Transmission networks
High-voltage connections let regions share generation, support one another, and move power over long distances.
Substations & protection
A substation is a controlled junction where power can be transformed, measured, connected, or safely disconnected by designed equipment.
Distribution networks
Local feeders, cables, and transformers connect the bulk electricity system to streets, buildings, and smaller generators.
Meters, power & energy
A meter records energy crossing a connection. Power tells you how quickly energy is being used at a particular moment.
The appliance & its circuit
A kettle, lamp, motor, or computer is a load: equipment that converts electrical energy into another useful form.
Balancing supply & demand
Electricity supply and use must remain closely matched while equipment, weather, and demand keep changing.
Energy storage
Storage takes in energy now and makes some of it available later, within both a power limit and an energy limit.
Solar panels & inverters
Photovoltaic cells produce DC electricity. An inverter makes that output usable by an AC installation and its connected grid.
Alternating & direct current
AC reverses polarity periodically; DC keeps one polarity. Conversion equipment connects the many places where both are useful.
Frequency & inertia
Frequency describes how often AC cycles repeat. Inertia and controlled responses influence how that rhythm changes after a disturbance.
Demand response
Flexible users can adjust consumption in response to an agreed signal, helping the system balance resources and manage peaks.
Microgrids & island operation
A microgrid coordinates local loads and resources and can be designed to operate independently of the wider grid.
What if demand rises?
Change both demand and available upward response in a fictional grid. Pin one set of assumptions as A, then compare the live result B.
How do demand and available upward response change the supply margin?
Add to or remove from the 100-unit baseline supply capability. Compare the same demand with different headroom.
- Scheduled supply
- 100units
- Available headroom
- 20units
- Unmatched demand
- 0units
Demand is met by 100 baseline units plus 0 units of response. 20 of the chosen 20 units of upward headroom remain.
03 / Compare A and B
TWO INPUTS. TWO CONDITIONS.Pin the current settings as A, then change either input to test B. A stays in memory only while this page is open. Shared links include the current B inputs, never the pinned A.
No A is pinned. Enable the interactive controls, choose settings and pin them to compare.
| Setting or result | A · Not pinned | B · Current |
|---|---|---|
| Demand relative to baseline | — | 100 % |
| Available upward headroom | — | 20 units |
| Scheduled supply | — | 100 units |
| Available headroom | — | 20 units |
| Unmatched demand | — | 0 units |
Inside the modelAssumptions, limits & sources +
The balancing principle is informed by grid-operation sources; all capacities are editorial teaching values. With demand of 140 and response capability of 20, supply is capped at 120 and 20 units remain unmatched. Raising the assumed response capability to 40 covers that demand. This changes a chosen limit, not a forecast of what real equipment can deliver.
- The baseline demand and scheduled supply are both 100 arbitrary power units, not measurements from a real system.
- Available upward response is a second control, ranging from 0 to 60 units with a starting value of 20. Supply is assumed able to reduce to match demand below 100 units.
- Scheduled supply = min(demand, 100 + available upward response). Unmatched demand = max(0, demand − scheduled supply). Available headroom = 100 + available upward response − scheduled supply.
- The result is a static balance after response. Network losses, location, ramp rates, stored-energy duration and contingency reserves are omitted. Changing the response control does not explain how that capability would be obtained.
- The model does not calculate frequency, blackout probability, cost or emissions. An uncovered shortfall means the chosen illustrative resources are insufficient, not that a particular real protection action will occur.
Model references: Australian Energy Market Operator: Guide to Frequency Control Ancillary Services · U.S. Environmental Protection Agency: Electricity Delivery and its Environmental Impacts · U.S. Energy Information Administration: Electricity glossary
Keep following the connections.
Sources & further reading
Original explanations informed by these sources. Diagrams are conceptual; local systems differ.
- How electricity is generated U.S. Energy Information Administration · 2023-10-31 · Source & rights record
- Photovoltaics and electricity U.S. Energy Information Administration · Not stated · Source & rights record
- Electricity 101 U.S. Department of Energy · Not stated · Source & rights record
- Batteries, circuits, and transformers U.S. Energy Information Administration · Not stated · Source & rights record
- How electricity is delivered to consumers U.S. Energy Information Administration · Not stated · Source & rights record
- Electricity glossary U.S. Energy Information Administration · Not stated · Source & rights record
- Electricity Delivery and its Environmental Impacts U.S. Environmental Protection Agency · Not stated · Source & rights record
- Solar Integration: Distributed Energy Resources and Microgrids Basics U.S. Department of Energy · Not stated · Source & rights record
- Measuring electricity U.S. Energy Information Administration · Not stated · Source & rights record
- Guide to Frequency Control Ancillary Services Australian Energy Market Operator · 2025-09-17 · Source & rights record
- Energy storage for electricity generation U.S. Energy Information Administration · 2023-08-28 · Source & rights record
- Solar Integration: Inverters and Grid Services Basics U.S. Department of Energy · Not stated · Source & rights record
- What is inertia? National Energy System Operator (Great Britain) · Not stated · Source & rights record
- Demand Response (DR) California Public Utilities Commission · Not stated · Source & rights record