As oil headed in the direction of $200 a barrel this week, VMware claimed that its virtualization widgetry has saved users 39 billion kWh since 1998, more power than it takes to heal and cool Denmark a year.

It calculates the savings at $4.4 billion.

Users can now consolidate 10 or more physical machines on a single server and reduce power consumption and cost by 80%-90%, VMware said.

By its calculations, every server virtualized saves about 7,000 kWh or four tons of CO2 emissions a year. Virtualized PCs can cut costs by 35%, it said, and hosting doubles the lifecycle of desktops and thin clients, reducing the environmental impact of replacement.

Most PCs eat 70%-80% of their rated power even when idle.