A phone charge is nothing. Everyone's phone charge is not nothing.
This is the number nobody in our category publishes, probably because it takes some care to state honestly. Charging a phone from a bench that filled its own battery at midday removes a small amount of demand from the network in the late afternoon, which happens to be the most carbon-intense and most constrained part of the day. Multiply it by a town, then by ten boroughs, then by the country. The number that matters is not how much energy a bench gives away, it is how much of that energy genuinely replaces a charge that would otherwise have come from a socket. That share is a slider on this page rather than an assumption buried inside it.
40,587 kWh
Grid energy displaced a year at the current model settings
Estimated12.6 kW
Demand removed from the late afternoon peak window
Estimated9.9 t
CO2e avoided a year, weighted to the hours it is actually avoided in
EstimatedGrid average intensity
Verified0.207 kg/kWh
Used for off-peak displacement
Evening peak intensity
Verified0.312 kg/kWh
Used for the 4pm to 7pm window
Sessions in the peak window
Assumed34%
Bench use is heaviest as people finish the day
Cost to the person charging
Verified£0
There is no meter, so there is nothing to bill
Move the displacement share first. It is the only input that can flatter us.
If every session at a bench were counted as a saving, the answer would be meaningless, because a share of that charging only happens because the bench is there. Set the share you believe. At fifty five per cent we are saying roughly half of bench charging replaces a wall socket and the rest is new convenience. A procurement team that wants a conservative number can drag it down and still see a result.
Assumptions
Benches deployed
1,600Charging sessions per bench per day
18Energy per session
9 WhSeasonal availability
78 per cent of nameplateShare that displaces a mains charge
55 per centEnergy given away
Estimated73,794 kWh
126 Wh per bench per day
Grid energy displaced
Estimated40,587 kWh
After the displacement share is applied
Peak demand removed
Estimated12.6 kW
Averaged across the three hour evening window
Charging sessions
Estimated8,199,360
A year, across the fleet
CO2e avoided
Estimated9.9 t
8.4 t at flat grid average
Homes equivalent
Estimated15.0
Against 2,700 kWh a year per home
Generator litres avoided
Estimated13,093
If the same energy came from event diesel instead
One high street, then ten boroughs, then the country.
These four rows all use the displacement share, energy per session and seasonal availability you set above, so the story cannot be improved by quietly changing the assumptions between rows.
- Benches
- 12
- Grid energy displaced
- 372 kWh
- Peak removed
- 0.1 kW
- CO2e avoided
- 0.1 t
- Free charges a year
- 75,161
- Benches
- 60
- Grid energy displaced
- 1,691 kWh
- Peak removed
- 0.5 kW
- CO2e avoided
- 0.4 t
- Free charges a year
- 341,640
- Benches
- 1,600
- Grid energy displaced
- 40,587 kWh
- Peak removed
- 12.6 kW
- CO2e avoided
- 9.9 t
- Free charges a year
- 8,199,360
- Benches
- 34,000
- Grid energy displaced
- 766,640 kWh
- Peak removed
- 238.0 kW
- CO2e avoided
- 186.1 t
- Free charges a year
- 154,876,800
Your own habit, with the negatives left in.
The fleet model above answers the policy question. This answers the personal one. It uses the same displacement share you set, and it deliberately reports the three things that work against the saving: charges that only happen because the power is free, any journey made to reach the bench, and the winter months when the bench is rationing and cannot serve the habit at all. Household savings use a unit rate of £0.245 per kWh.
Your habit
Charges taken at a bench per week
4 a weekEnergy per charge
9 WhBenches within an easy walk
2Walk to the nearest bench
4 minShare of charge trips made by car
0 per centMonths the bench can serve at full rate
8 monthsEnergy taken from benches
Estimated1.59 kWh
A year, after winter rationing
Kept off your meter
Estimated0.88 kWh
Worth about £0.21 a year
Grid carbon avoided
Estimated0.18 kg
CO2e a year, at the grid average
Net effect
Estimated−0.18 kg
CO2e a year, after any car trips
Charges that are new demand
Estimated80
A year. Not a saving, and counted separately
Charges winter cannot serve
Estimated31
Deferred by rationing rather than assumed away
Carbon added by driving to charge
Estimated0.00 kg
Three kilometre round trip in an average car
People one nearby bench can serve
Estimated91
At your rate of use, before rationing
Reading
Net saving of 0.2 kg CO2e a year for one person. Trivial alone, which is the whole point: the same habit across a town is where the number becomes a network effect rather than a gesture.
Induced demand
Free power invites top-ups that would not otherwise happen. Those charges are real load on the bench and they are not a grid saving. The calculator shows them as a separate number rather than absorbing them.
A journey made to reach the bench
If somebody drives to charge, the trip wipes out the saving many times over. Three kilometres in an average car costs roughly the same carbon as a hundred phone charges. This is the strongest argument for siting benches where people already sit.
Winter rationing
A December bench in the north of England generates a fraction of a June bench. Charging is the first thing the priority logic sheds, so some of the habit simply cannot be served and the model defers those charges rather than pretending they happened.
Embodied carbon comes first
The bench spends its carbon at manufacture and earns it back slowly through delivered energy. The delivered-energy line is the smallest of the offset levers, and the materials and take-back lines are where the real reduction sits.
The kilowatt hours are the small part. Where and when they land is the point.
Peak demand at the most carbon-intense hours
A bench discharges from a store it filled earlier in the day, so the relief lands in the late afternoon and evening window rather than at midday. That is the part of the curve where each avoided kilowatt hour is worth the most in carbon terms.
Charge anxiety that turns into a car journey
People cut a visit short, drive home early or take a taxi because a phone is about to die. A charge point where people already sit removes that trigger. We report this as a behavioural effect, not as a carbon number, because it cannot be measured from the bench alone.
Single-point charging queues in venues
Sites currently solve this with a powered locker on a mains spur, which needs a cable, a meter and a bill. Distributed self-powered seating removes both the spur and the queue.
Diesel at events and temporary sites
Where a generator is genuinely removed from a plan rather than merely left idle, the displaced energy converts directly into litres not burned. This is the one line where the saving is large per unit.
We would rather publish the limits than have a buyer find them.
Replace generation capacity. A national fleet of benches is a distributed peak-shaving layer, not a power station, and we will not present it as one.
Move a large organisation's total footprint on its own. The material carbon story is in the material and the take-back, not in the electricity.
Work without honest displacement accounting. If every session is counted as a saving, the number is worthless, which is why the displacement share is an input on this page rather than an assumption inside it.