Compare two fictional proposals delivering the same 4000 kWh of useful electricity per year for 10 years. A (a local renewable package) has initial embodied emissions 9000 kg CO₂e and operating emissions 0.05 kg CO₂e per delivered kWh. B (the current fuel-based supply) has initial emissions 1000 kg CO₂e and operating emissions 0.5 kg CO₂e/kWh. The supplied rates include operating losses; ignore replacement and disposal only for this first calculation. Find total emissions over the stated horizon and the equal-emissions time. Then recommend how the decision should account for this constraint: the higher upfront payment competes with classroom spending, while outages interrupt lessons. Do not assume these fictional factors describe actual products.

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Over 10 years: A 11000 kg CO₂e, B 21000 kg CO₂e. Equal-emissions time 4.4444 years. A has the lower modelled total; adoption also depends on the stated service and stakeholder constraints. Both proposals deliver the same useful service, so their operating emissions can be compared on a common boundary. Over 10 years the delivered energy is 4000 × 10 = 40000 kWh. Add initial and operating contributions. A gives 9000 + 40000 × 0.05 = 11000 kg CO₂e; B gives 1000 + 40000 × 0.5 = 21000 kg CO₂e. A starts with 8000 kg CO₂e more embodied emissions but saves 1800 kg CO₂e each year of operation. Dividing gives an equal-emissions time of 4.4444 years under the constant-rate assumptions. A carbon ranking is only one decision input: the higher upfront payment competes with classroom spending, while outages interrupt lessons. Discuss who receives the benefits, who pays upfront, and whether either proposal reliably delivers the promised service before choosing. Make the recommendation conditional on verified service life, repair and replacement needs, disposal and representative operating factors. The stated calculation intentionally omits those effects, so it cannot establish the full life-cycle impact or guarantee that the ranking survives changed assumptions.

Electricity for a village school

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