Category: Phones

Key Takeaways

1. Wireless charging is less efficient than wired charging, wasting around 35% more energy.
2. Wired charging efficiency is about 90-95%, while wireless charging ranges from 60-80% efficiency.
3. A smartphone charged wirelessly consumes approximately 1.7 kWh more annually than one charged with a wired connection.
4. Globally, the additional energy demand from wireless charging could reach about 1.7 TWh per year, enough to power around 680,000 homes.
5. The energy wasted from wireless charging could potentially power a city like Leipzig or charge approximately 773,000 electric cars annually.

---

Every so often, I consider getting a wireless charging pad for my phone. I know I’m a bit behind the times, but there’s one question that keeps stopping me (plus, a bit of laziness to actually look into it): how much energy does wireless charging really waste?

Digging into the Numbers

So, I finally took the plunge and did some quick calculations. I began by checking the efficiency of both wired and wireless charging. The information comes from a report by the International Energy Agency called “Energy Use for Wireless Charghing.”

As per this report, charging a battery wirelessly consumes around 35 percent more energy. Other sources, like hichaintech.com, indicate that wired charging loses about 5–10 percent of energy as heat, resulting in an efficiency of around 90–95 percent. With systems like Qi and MagSafe, there are also coil losses that depend on distance, alignment, and power level, leading to overall efficiencies ranging from 60 to 80 percent, or a loss of 20–40 percent.

A Look at a Typical Smartphone

Let’s break this down using a single smartphone for context. Assuming a 15 Wh battery (approximately 4,000 mAh) that gets fully charged once daily, the numbers present as follows:

– Wired charging (90% efficiency)
– 15 Wh / 0.9 = 16.7 Wh
– Annual consumption: 16.7 Wh × 365 = 6,095 Wh = 6.1 kWh
– Annual cost: 6.1 kWh × €0.30 = €1.83

– Wireless charging (≈70% efficiency)
– 15 Wh / 0.7 = 21.4 Wh
– Annual consumption: 21.4 Wh × 365 = 7,811 Wh = 7.8 kWh
– Annual cost: 7.8 kWh × €0.30 = €2.34

For an individual, the cost difference is minimal. However, from an ecological standpoint, things start to get intriguing — there are billions of smartphones in use all around the world.

The Bigger Picture

As of recent estimates, there are about 7.3 to 7.4 billion smartphones in use globally. Back in 2021, around 1 billion of these (approximately 13.5%) supported wireless charging, according to Strategy Analytics. Today, that percentage is likely higher — perhaps between 15 to 25 percent. Not every one of those phones is charged wirelessly, but let’s assume 1 billion devices are, each using 1.7 kWh more each year (as calculated earlier).

1 billion devices × 1.7 kWh = 1.7 TWh per year (1 TWh = 1 billion kWh = 1,000,000,000 kWh)

This means the additional energy demand globally due to wireless phone charging could amount to around 1.7 TWh every year. With an average household consuming roughly 2,500 kWh annually, that’s sufficient to power about 680,000 homes for a year.

Alternatively, the energy wasted through Qi and similar wireless charging could power an entire German city like Leipzig or Hannover for a year — or charge around 773,000 electric cars (assuming each one uses 2,200 kWh per year). Generating this amount of energy would need over 200 wind turbines (each rated at 3 MW with an average utilization of 30%).