IELTS Listening 實戰 18 再生能源演講（Part 4 風格）

Good morning. Today's lecture surveys the four main renewable energy technologies driving the global transition away from fossil fuels — solar, wind, hydropower, and an emerging fourth, geothermal. By the end you should understand each technology's mechanism, its current contribution, and the principal barriers to scaling it further.

Let's begin with solar photovoltaics, or PV. The mechanism is straightforward: silicon-based panels convert sunlight directly into electricity through the photoelectric effect. Costs have collapsed — a typical residential panel today costs about ninety percent less than it did in 2010. As a result, solar is now the cheapest form of new electricity generation in most countries. The main barrier is intermittency — solar produces nothing at night and far less on cloudy days — which means it must be paired with storage, typically lithium-ion batteries. Storage costs are falling but remain the chief obstacle to a fully solar grid.

Moving on to onshore and offshore wind. Wind turbines convert kinetic energy from moving air into electricity via a generator. Onshore wind is now also cheaper than fossil fuels in most regions, while offshore is more expensive but has higher and more consistent output — wind speeds at sea are stronger and steadier. The UK leads the world in offshore wind, with around fourteen gigawatts installed as of 2024. The challenges are different by location: onshore wind faces planning resistance — communities object to visual impact and noise — while offshore faces engineering challenges and high construction costs.

The third technology is hydropower, the oldest of the four. It generates electricity by passing water through turbines, typically at a dam. Hydropower currently provides about fifteen percent of global electricity — more than wind and solar combined, though that ratio is shifting. The advantages are reliability and built-in storage: a reservoir is essentially a battery. The disadvantages are environmental — dams flood ecosystems, displace people, and disrupt fish migration — and geographical: only some countries have the rivers and topography to expand hydropower significantly. New large dam projects are increasingly controversial; most current growth is in smaller "run-of-river" schemes that don't require large reservoirs.

Now, the fourth and most under-discussed: geothermal energy. Geothermal taps heat from beneath the Earth's surface, either to generate electricity directly via steam turbines, or for direct heating. Iceland generates around twenty-five percent of its electricity this way, exploiting its volcanic geology. Until recently, geothermal was thought viable only in volcanically active areas. However, enhanced geothermal systems — where engineers drill deeper and inject water to create artificial reservoirs — promise to extend geothermal's reach to far more locations. The technology is still expensive, but a successful demonstration project in Utah in 2023 drew significant investor interest.

Now, let me bring these together with three cross-cutting challenges that affect all four.

First, grid integration. Renewables produce electricity differently from fossil plants — variably, and often far from where it's consumed. Building transmission lines to connect remote wind and solar farms to cities is slow and politically contested.

Second, materials supply. Solar panels need silicon and silver; wind turbines need rare earth metals; batteries need lithium and cobalt. Current mining capacity is insufficient, and much of it is geographically concentrated, raising both supply security and human-rights concerns.

Third, the just transition — ensuring that workers and communities currently dependent on fossil-fuel industries are not left behind as the transition accelerates. Studies suggest that perhaps ten million fossil-fuel jobs will need to be replaced or retrained by 2050.

In conclusion, the renewable transition is no longer constrained primarily by technology cost — solar and wind are already cheaper than fossils. The remaining barriers are largely systemic: storage, grid, materials, and labour. Next week we'll look at policy responses to each. Please read chapter twelve.

Questions 1-6 — Complete the lecture notes. Write NO MORE THAN TWO WORDS AND/OR A NUMBER.

Four Renewable Technologies

Solar PV

• Cost has fallen by approx. (1) _______ % since 2010
• Main barrier: needs (2) _______, typically lithium-ion batteries

Wind

• UK has installed about (3) _______ GW of offshore wind by 2024
• Onshore faces (4) _______ resistance from communities

Hydropower

• Provides about (5) _______ % of global electricity
• New growth mostly in (6) _______ schemes (no large reservoirs)

Questions 7-10 — Complete the summary. Write NO MORE THAN TWO WORDS.

Iceland generates around 25% of its electricity from geothermal, exploiting its (7) _______ geology. New "enhanced geothermal systems" use deeper drilling and water injection to create (8) _______ reservoirs, extending geothermal's reach. Three cross-cutting challenges remain: grid integration, materials supply, and the (9) _______ transition. Around (10) _______ million fossil-fuel jobs will need replacing or retraining by 2050.