How many deaths will you prevent?

Develop estimates for three main numbers by which your 150 Tons projects can be compared. These numbers will be rough estimates, and that's OK! Just document your assumptions and you can always go back and update your calculations as you get more detailed information.

A few things to keep in mind here. We won't get the numbers exactly right, but that's no excuse for not even having estimates. These estimates will help guide your decisions but shouldn't be the definitive last word on which projects are the 'best.' Many other factors, such as feasibility and risk, that we don't calculate here are also important.

Preventing deaths 

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Estimate 1 - Cost information - How much money will your idea require? 

Basically, how do you know your idea will be profitable? If you are going to make something that will cost $500, will you be able to sell it for more? If you are going to offer a consulting service - will people pay you enough to justify spending your time? There are lots of calculators like this one Links to an external site. to help you with this. 

Estimate 2 - Energy Return on Investment (EROI) - How much energy will your innovation save or produce?

The process for developing this estimate is going to be different for everyone, but here are a few general tips.

• Estimate the amount of unsustainable energy you will save (or sustainable energy you will produce). For example, "Each home we audit will use an average of 2000 kwh less electricity each year."
• Make sure you also consider any major energy uses of your innovation. For example, "we will use drive about 40 miles for each audit, using about one gallon of gasoline." 
• Subtract the energy usage from the savings to determine the net energy savings. Online tools like the U.S. EPA's Greenhouse Gas Equivalency Calculator Links to an external site. can help you convert between different units. In the example, the gas usage is negligible compared to the home audit savings. 
• Estimate the amount of energy your innovation will save in a year assuming everything goes as planned. For example, "I hope our energy auditing company will serve 1000 homes per year, for a total of 2 million kwh of electricity saved each year."

Estimate 3 - How many deaths will your innovation prevent?

Once you have the EROI number, this should be a pretty straightforward calculation.

• Convert the EROI to CO2 emissions. Again, an online calculator such as the U.S. EPA's Greenhouse Gas Equivalency Calculator Links to an external site. can help. In the energy audit example, 2 million kwh is equivalent to about 1400 tons of CO2.
• Then, divide the number of tons of CO2 emissions by 150 tons per climate change related death. So for the audit example, 1400/150 is over 9 deaths prevented - each year.

Discussion post

Share your estimates for costs, EROI, and deaths prevented in the discussion forum. Include enough supporting documentation and calculation so others can follow your logic.