August 27th, 2012

Ann Vole

the biggest impact on the environment

Using 2008 data (population and world energy creation) I come up with:
77.4 GJ/person-yr
Using the low end of recommended calorie intake and converting the units:
3.36 GJ/person-yr
Two estimates of the portion of energy used directly and indirectly to get food on our table (in USA and in UK) were both in the mid 70s of percent so to be conservative I will use 70%
77.4 x 0.7 = 54.2
how much energy does it take to make food energy?
54.2 / 3.36 = 16.13 (note I kept full numbers in the calculator)
It takes 16 times as much energy to make your food then the energy in your food. This is also a global number so it includes the low energy use of the poorest parts of the world but assumes they eat the recommended calories.

I did a calculation based on several sources so might be wrong but one GJ of natural gas produces 55.1 tons of CO2 (coal and other fuels would be more) so:
55.1 x 54.2 = 2987
Growing your own food could save 3000 tons of CO2 per year per person
Ann Vole

new way of looking at heat storage

I was always looking at storing high heat to make steam on demand to run a turbine. Turbines are based on temperature and pressure difference as long as the working fluid has a phase change within the turbine. Ice-to-water has one of the highest releases of energy in common substances (aluminum and ammonia are also high with atmospheric pressure phase changes at
660.32 °C and −77.73 °C respectively). Making a turbine that operates between freezing temperature of water and some easy-to-store temperature (not far from room temperature) might be the better way of storing solar heat for later use. A heat pump operating by solar would create and store the ice and it's waste heat would pre-heat the solar heat that is stored in soil. This system of extracting heat (the turbine mentioned above) would power the heat pump during solar input.