How to calculate electricity CO₂ emissions and intensity
Total emissions tell you how much CO₂ was produced. Emissions intensity tells you how much was produced per unit of electricity served. You need both to judge a change.
Keep the accounting boundary consistent: convert power into energy, apply the generator’s emissions factor, and divide by electricity actually served.
Calculate emissions from dispatched electricity
In PowerLab, coal produces 0.90 tonnes of CO₂ per MWh of electricity and gas produces 0.37. The other technologies have zero direct operational emissions in the model. These are illustrative factors; they do not include lifecycle emissions from construction, fuel supply or manufacturing.
CO₂ (tonnes) = energy (MWh) × emissions factor (t/MWh)
A gas plant producing 2 GW for one hour generates 2,000 MWh and emits 740 tonnes under these assumptions. Always use dispatched output rather than installed capacity. An idle plant does not emit from electricity generation in this simplified calculation.
Divide by served electricity, not unmet demand
Imagine an hour with 1 GW of coal, 2 GW of gas and 3 GW of zero-direct-emissions generation. Ignore losses and storage for this example and assume all 6 GW serves demand.
Coal emits 900 tonnes and gas emits 740 tonnes. Total emissions are 1,640 tonnes. Dividing by 6,000 MWh gives 0.2733 tonnes/MWh, or approximately 273 g/kWh.
If some electricity is lost in transmission or used for charging, it does not count as served customer demand in PowerLab’s denominator. That can raise the current-hour intensity. Unserved demand is also excluded: dividing by electricity that customers never received would make the indicator misleading.
Avoid counting storage emissions twice
When thermal generation charges storage, the associated operational CO₂ is counted in the charging hour. When the battery later discharges, those same tonnes are not counted again. Storage still incurs losses, so it needs more charging energy than it eventually returns.
Compare a full cycle rather than only the apparently clean discharge hour. Whether storage reduces total emissions depends on what charges it, which generation it replaces later, and the losses involved. The storage device alone does not guarantee a reduction.
The national result adds emissions from all generators. Regional emissions in the game are production-based: exported electricity’s emissions stay with the producing region. A local reduction can therefore reflect relocated generation rather than a national improvement.
How the game links CO₂ and GDP
Grid Operator applies a deliberately invented quarterly growth penalty using a region’s rolling local CO₂ per MWh of underlying demand. The rule subtracts 0.8 times that ratio, capped at 0.8 percentage points per game quarter.
For a rolling ratio of 0.5 t/MWh, the penalty is 0.4 percentage points. This combines with reliability, affordability, underlying growth and outage effects. A game quarter represents 24 game hours; it does not mean real GDP changes that quickly.
This is a teaching mechanic, not an empirical estimate of climate damage or local air-pollution effects. CO₂ and local air pollutants are not interchangeable measures. Use the rule to explore the game’s trade-offs, not to estimate a policy’s real economic benefit.
Reduce emissions without simply cutting service
The A cleaner grid challenge asks for at least a 30% reduction in average hourly national CO₂ over 24 settled hours. It also requires at least 99.5% of demand to be served and at least 99% of the starting average demand to remain. Emergency demand reductions are locked during the challenge.
Look for coal that can be displaced, suitable clean-generation sites and transmission bottlenecks. Use the regional profiles to check the whole day. A low-carbon midday snapshot is not enough if an evening shortfall forces more fossil generation later.
Put the idea to work.
Start A cleaner grid from the Operator Missions section. Compare the baseline with a full 24-hour result after your investments complete, and check emissions alongside demand served.
Take the CO₂ challenge →Common questions
What is the difference between emissions and emissions intensity?
Emissions are total tonnes of CO₂. Intensity divides emissions by electricity served, for example in g/kWh.
Does zero operational CO₂ mean zero environmental impact?
No. PowerLab’s operational accounting omits lifecycle and other environmental impacts.
Sources & model boundary
Examples and calculations: PowerLab’s illustrative model, checked against the local simulation. Background reading: PowerLab’s documented model assumptions.
This guide is educational. Grid Operator’s network, economics and construction are simplified game assumptions; Market Lab’s uniform-price model is a separate one-hour experiment.