# What is the carbon footprint of running a Spike Prime robot? [closed]

We are trying to calculate how much carbon is emitted from running a Spike Prime robot off one charge (roughly 8-10 hours)?

• I dont’t think Bricks.se.com is the right place to get answers to homework questions, Jan 18 at 11:31
• I’m voting to close this question because this is asking the community to complete a homework assignment Jan 18 at 11:32
• no, answers are here Jan 18 at 11:43
• @PhilB. Even if the question is about a homework assignment, it has a clear connection to LEGO bricks with a less-known but exactly available data (the total amount of energy in a SP battery), which is essential to calculating the answer. Providing this information would be squarely in the focus of Bricks.SE - but solving the assignment on the other hand is of course not. I'd suggest editing the question to emphasize this information need. Jan 19 at 8:37

## 2 Answers

None, running the robot doesn't produce any carbon as it doesn't run on fossil fuels but consumes electrical energy.

Producing the electrical energy to charge the battery does have a carbon footprint, so I'm going to assume you meant to ask that. I'm also going to assume that you completely deplete the battery before you recharge it. Specs say that the battery capacity is 2100 mAh at 7.3 V... Hence, power usage is 2100 x 7.3 / 1000 = 15,33 Watt hours (Wh) = 0.01533 kWh

How much carbon is emitted depends on how the electricity to charge the battery is produced, which basically depends on how electricity is generated where you live. assuming you are from the US I found the following data: https://www.eia.gov/tools/faqs/faq.php?id=74&t=11 Which states that 0.855 pounds of CO2 is produced per kWh

So I get 0.01533 kWh times 0.855 ~=~ 0.0131 pounds = 0.209 ounces

The official rechargeable battery for the large hub has 2100mAh capacity at 7.3V - This lets you calculate the total watt-hours in one full charge (let us know if you need help with this), which you'll then need to multiply by the CO2-factor of your current local energy provider.

This last part makes the question ultimately not answerable in a universal way, as you'll get entirely different results if the electricity you use comes from a hydro power plant or from a plant burning brown coal.