Granola Power Management

Today’s desktop computers pack a lot of power, both in terms of horsepower and computing power. Granola aims to reduce carbon emissions produced by overpowered but underutilized computers by taking advantage of Dynamic Voltage and Frequency Scaling (DVFS) support on most modern Intel and AMD processors. That is, you install the Linux or Windows version of Granola on your computer and see your power savings instantaneously (on Ubuntu, click Cumulative Reporting under Preferences menu).

The default Power Management Policy is set to MiserWare which allows Granola to dynamically adjust the power so that you only use what you need. Also, the Granola website allows you to show your power savings stats for up to 5 machines for free (registration required).

Granola’s Impact – A Conservative Estimate

Every single watt contributes to climate change. In the US, each kilowatt-hour generated means 1.31 more lbs (.59kg) of carbon in our atmosphere. Laptops consume 15-45 watts, and a typical desktop uses 65-250 watts or even more. Even assuming the lowest numbers, that means each system left running needs 569kWh every year. That’s 763lbs or 346.2kg of carbon for each and every computer.

Granola reduces energy waste

That’s not so bad if the system is always doing work. That’s rarely the case, though – most computers sit idle for hours every day. And even when someone is actually using them, most systems are not as energy-efficient as they could be. Granola reduces energy waste by as much as 35% of the total system energy. For a 65 watt desktop, saving only 10% means 56.9 kWh or 76.4lbs of CO2 a year.

Real-world results

One evergreen tree, on average, takes in about 83lbs of CO2 each year (37.6kg). That means for every computer running Granola and saving 10% system energy, the minimum reduction in carbon output is 91.9% as much as planting a tree. Every 1000 users is like 919 evergreens!

According to the EPA, the average car on the road releases 5.03 metric tons of carbon dioxide yearly. That sounds like a lot, but Granola users begin to add up pretty quickly. Every 145 people using Granola is like getting rid of a car. 10,000 users is like getting rid of 69 cars!


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