# Pela Lomi and the Carbon Cost of Electricity

Recently, this "automated composter" showed up in my instagram feed and I was curious about the carbon cost. If it's reducing the compost in only 4 hours it must have a decent size electrical heater inside.It states that it uses 1/5th the energy of an energy star refrigerator (~350kWh/yr), so that's 70kWh/yr. If people run the machine 2 times per week like they recommend and it takes about 600Wh to do a cycle, then this sounds like an accurate estimation.Based on the EPA's estimate of the US electrical grid carbon footprint of 709 grams of CO2 per kWh, that is 49kg CO2e/yr, per unit.If they sold 10,000 units (and based on the crowdfunding dollars, they might have just done so) then that would be 490,000 kg of CO2 per year.This is the same as:

- 14,196 BBQ propane cylinders per year
- 383,815 lbs of coal burned per year
- 39,074 gallons of gasoline burned per year
- 34,111 gallons of diesel burned per year
- 75.5 average passenger cars' consumption over one year

*every week*that the crowdfunding backers use this composter.Now for curiosity's sake, let's assume that we generate that electricity from biofuel that's made from soybeans.Let's assume that electricity was made from biodiesel, and the conversion between diesel and electricity was 60% efficient (unreasonably high), and, you can make 570 gallons of bio diesel from a yearly harvest of one acre. Then, we must harvest about 100 acres of soybeans per year to power 10,000 of these composters.