Nuclear Fusion Energy

Nuclear fusion is when two light nuclei join (fuse) to make a heavier nucleus and release energy. It powers the Sun and other stars and is being researched on Earth as a future energy source.

Nucleus Basics

A nucleus contains protons (charge +1) and neutrons (charge 0). In fusion, small nuclei combine to form a larger, more stable nucleus.

Fusion in the Sun

The Sun mainly fuses hydrogen into helium. This releases huge amounts of energy that reaches Earth as light and heat. That solar energy also drives winds and weather.

A Common Fusion Reaction (on Earth)

Scientists often study deuterium (²H) and tritium (³H), two forms of hydrogen:

$$^2_1\text{H} + ^3_1\text{H} \rightarrow ^4_2\text{He} + ^1_0\text{n} + \text{energy}$$

Energy is released because the final products have slightly less mass; the “missing” mass becomes energy by $E = mc^2$.

How Could We Use Fusion to Make Electricity?

Fusion releases energy as heat. In a power plant, that heat would make steam to turn a turbine, which spins a generator to produce electricity (similar end stage to many power stations).

What Does Fusion Need?

• Fuel: Deuterium (from water) and tritium (made from lithium). Deuterium is abundant; tritium can be bred in the reactor.
• Very high temperature: over 100 million °C, forming a hot, charged gas called plasma.
• Containment: strong magnetic fields hold the plasma away from the walls (a doughnut-shaped device called a tokamak or a stellarator), or powerful lasers compress tiny fuel pellets (inertial confinement).

Advantages

• Potentially large-scale energy with no carbon dioxide during operation.
• Fuel is widely available (deuterium in water; lithium is common).
• No chain reaction like fission; very low risk of runaway reactions.
• Produces far less long-lived radioactive waste than fission.

Disadvantages (Current Challenges)

• Not yet commercially available; experiments are still improving.
• Needs extreme temperatures and precise control, which is difficult and expensive.
• Some materials become radioactive from neutron exposure; safe handling is required.

Fusion vs Fission

• Fusion: small nuclei join (e.g., hydrogen → helium).
• Fission: a heavy nucleus splits (e.g., uranium splits into smaller nuclei).

Common Misconceptions

• Fusion reactors cannot explode like nuclear bombs; the plasma stops if conditions are not perfect.
• Fusion is not the same as “solar power,” but the Sun’s energy comes from fusion.