Moving energy: wires, pipes and ships
Energy is rarely used where it is found. Wires, pipes, ships and trains move it, each with its own physics, losses and costs, and the cost of moving a unit of energy 1,000 km differs more than a hundredfold between carriers. Electricity grids must balance every second, fuels carry their own storage with them, and a few narrow straits carry a large share of world trade.
Understanding Energy / Module 9Moving energy: wires, pipes and ships
Energy is rarely used where it is found. Wires, pipes, ships and trains move it, each with its own physics, losses and costs, and the cost of moving a unit of energy 1,000 km differs more than a hundredfold between carriers. Electricity grids must balance every second, fuels carry their own storage with them, and a few narrow straits carry a large share of world trade.
4 parts · 14 sections · about 50 minutes · 0 of 4 parts readBy the end you will be able to
- Explain why power lines run at hundreds of thousands of volts, using the I^2R rule
- Compare AC and HVDC transmission and say when each is the better choice
- Describe how grid operators keep supply and demand matched every second, and why grids have become a bottleneck
- Compare the energy and money cost of moving oil, gas, LNG, coal, hydrogen and heat
- Identify the main chokepoints in world energy trade and what the 2026 Hormuz crisis showed about them
Contents
- Part 1 Why electricity travels at high voltage
Electricity is the most flexible energy carrier, but it cannot be put in a box and shipped. It flows through metal, and metal resists. Much of the design of a power system, from the height of the towers to the size of the transformers, follows from one simple relation between current and heat.
- Heat in a wire grows with the square of the current
- Alternating current won because its voltage is easy to change
- Direct current returns for long distances and under the sea
- Part 2 Grids are machines that must balance every second
A power grid is usually drawn as a map of lines, but it behaves more like one huge machine. Thousands of generators spin in step, millions of loads switch on and off, and almost nothing is stored in the wires. Keeping that machine stable is a continuous job, and as wind and solar grow it is becoming harder and more expensive.
- Supply must equal demand at every instant
- Distribution holds most of the wires, money and losses
- The grid has become the bottleneck
- Part 3 Moving molecules: pipelines, tankers, LNG and coal trains
Fuels have one big advantage over electricity: they can be stored on the way. A tanker at sea or a pipeline full of oil is also an inventory. But each fuel's physical form decides how it moves. Liquids are easy, gases are bulky and must be squeezed or chilled, and solids need trains, conveyors and ships.
- Pipelines move oil cheaply as long as they stay full
- Tankers turned oil into a world market
- Gas needs either steel pipes or deep cold
- Coal moves by the trainload and the shipload
- Part 4 New carriers, the cost of distance and chokepoints
The energy transition adds new things to move, notably hydrogen and low-temperature heat, and puts more weight on wires. Comparing carriers on a common basis, cost per MWh moved 1,000 km, shows why some trades are almost free and others barely make sense. It also shows how much risk sits in a few narrow places.
- Hydrogen is easy to pipe and hard to ship
- Heat networks move warmth across a city, not a continent
- The cost of distance differs a hundredfold between carriers
- Chokepoints concentrate the risk
- Wrap-up Key terms, try it in the table, final quiz, sources