(Bloomberg) — The vast Illinois factory floor that will produce electric delivery vans for Amazon.com Inc. is starting to fill up. Battery and chassis assembly here. Tire storage there. A titanic, three-story metal press.

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Sometime next year, the plant’s workers will complete the first van. A decade later, if all goes according to plan, van No. 100,000 will roll off the line, completing the biggest electric vehicle purchase in history. By the time Amazon has all these zero-emission vehicles on the road, around 2030, it will eliminate an estimated 4 million metric tons of CO2 now belched out each year by gasoline-powered vans and trucks.

That would wipe out a small company’s entire contribution to the emissions warming the planet. But for the largest online retailer, the savings represent roughly 8% of its carbon footprint. How Amazon hopes to tackle the other 92%—as well as any other emissions