Posts Tagged ‘carbon footprint’

21st April
written by simplelight

I frequently meet with the executives of alternative energy companies. Unfortunately, in most cases, the price of the electricity they’re generating is too high or the payback period for the required capital investment is too long.

In the past two years (April 2007 to March 2009) my wife and I have used 13,226 kwh at an average price of 13.3 cents per kwh (including all the taxes, distribution costs etc.). The total cost was $1,761 which amounts to $2.42 per day. We are fairly efficient and only use about 18.2 kwh per day which, according to PG&E, is a lot lower than average.

Nevertheless, it is hard to contemplate spending $10-20k to install any type of edge electricity generation when we can so easily pull it off the grid.

California, though, has a tiered rate system. Similar to tax rates, the more electricity you consume the higher your rate per kwh. The following are the approximate rates in California as of today.

  • Baseline
  • Tier 2 (up to 130% of baseline) — 13 cents per kwh
  • Tier 3 (up to 200% of baseline) — 21 cents per kwh
  • Tier 4 (up to 300% of baseline) — 37 cents per kwh
  • Tier 5 (over 300% of baseline) — 44 cents per kwh

The baseline rate varies by geography and season but is priced around 11.5 cents per kwh and includes about 23 kwh per day currently.

If you are consuming enough electricity to be hitting tiers 4 and 5 then it begins to make sense to install solar panels or fuel cells such as those provided by ClearEdge Power.

1st May
written by simplelight

I’ve heard before that walking a mile emits more carbon than driving a mile so decided to investigate for myself.

A 190lb human walking at 3 miles per hour would expend 302 kCal. Therefore, covering a mile would take 20 mins and approximately 100 kCal. Apparently it takes 7-10 kCal of fossil fuel to produce 1 kCal of food. The upper end of the range assumes a diet of highly processed food and meat being transported long distances. The lower end of the range assumes a more vegetarian-centric diet and locally produced food.

Therefore,  a 1 mile walk requires 700 – 1,000 kCal of fossil fuel energy.

Driving a 30 mile per gallon car for one mile at 60 mph takes 1 minute and 1/30th of a gallon of gas. One gallon of gasoline contains approximately 30,000 kCal of fossil fuel energy.

Therefore, a 1 mile drive requires approximately 1,000 kCal of fossil fuel energy.

Depending on where you source your food and what you eat, it doesn’t make much difference in terms of carbon emissions. Driving a car one mile is far cheaper than walking a mile. But the health benefits of walking a mile far outweigh the cost.