Technology and the environment

Making, running and disposing of devices: materials, data centres, e-waste and what helps.

F12.5Technology and societyGCSE15 min

Do this lesson in the simulator

Computers feel clean: no smoke, no noise. The cost is somewhere else, in the power station, the mine and the landfill. This lesson works out what a device really costs the environment, over making it, running it, and throwing it away.

Making it

Every device starts as material dug out of the ground. Phones, laptops and robots need rare earth metals and minerals such as lithium, cobalt and tantalum. Mining them uses energy and water, damages habitats, and in some places involves dangerous or child labour. Most of a phone's lifetime carbon footprint is spent before it is ever switched on.

Running it

Electricity is the running cost, and it is not only the device in your hand. Data centres, the warehouses of servers behind every website, video and cloud file, use a large and growing share of the world's electricity, much of it for cooling. Where that electricity comes from decides how much carbon it emits.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

# a class of robots and laptops, running for an afternoon
watts = 60                       # one robot and its laptop
hours = 3
devices = 15
kwh = watts * hours * devices / 1000
print("energy:", kwh, "kWh")
print("cost: £", round(kwh * 0.28, 2))          # 28p a unit
print("carbon:", round(kwh * 190), "g CO2")     # about 190 g a unit on the UK grid

Run this in the simulator

Throwing it away

E-waste, electronic waste, is the fastest growing kind of household waste in the world. Thrown away, devices leak lead, mercury and cadmium into soil and water, and the materials in them are lost. Some is shipped abroad and taken apart by hand in unsafe conditions.

The UK's WEEE regulations (Waste Electrical and Electronic Equipment) make producers pay for collecting and recycling the devices they sell, which is why shops take old electricals back.

What helps:

  • keeping devices longer: the biggest single saving, because making them costs the most;
  • repairing rather than replacing, and designing devices that can be repaired;
  • recycling properly, so the metals return to use;
  • energy-efficient hardware, sleep modes, and data centres run on renewable electricity;
  • efficient code: a program that does the same job with less work uses less power on every machine that runs it.

That last one is your job. The efficiency you measured in lesson F5.6 is an environmental question as well as a speed one.

Task: the classroom's footprint

For each device in devices (a name, its watts, and how many hours it runs a day), work out the energy for a 190-day school year across count of them. Print <name>: <kwh> kWh rounded to 1 decimal place, then at the end total: <kwh> kWh, cost: £<n> at 28p a unit rounded to 2 decimal places, and carbon: <n> kg CO2 at 190 g a unit, rounded to the nearest whole number.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

days = 190
count = 15                      # how many of each device the class has
# name, watts, hours a day
devices = [("laptop", 50, 5), ("robot charging", 8, 1), ("projector", 220, 4)]

Challenges

  1. The projector is replaced with one using 120 W. How much carbon does that save in a year?
  2. Which costs more over five years: making 15 new laptops, or running them? Look up a figure for making one.
  3. Name three things a school could do to cut the footprint of its computers.