Spicific energy: energy/mass
Energy density:energy/volume
Specific power: power(input or output) / mass
Power density: power/volume
Efficiency: Energy in/ energy out
solar: sunlight——卡路里 20000-30000years ago
Energy Slaves reflections: essays - Stuart McMillen blog
an average human being was placed on a rowing machine (or exercise bike, or treadmill…) for a year of 250 eight-hour shifts, the total amount of energy that the person could expend into the machine would be *500 megajoules.*It is roughly equivalent to the energy stored within 14 litres of gasoline Technologies like Energy Floors, that rely on human bodies to generate energy, will only ever be a small-scale gimmick
**EROEI(energy returned on energy invested)——**Net energy
Scrutinising the ‘net energy’ (EROEI) of our energy sources is a worthwhile exercise. It forces us to ask the question “how many energy slaves do we get in return from each energy slave that we send to work?” This is an important question for us to consider as a civilisation.
EROEI一直存在边际效应，需要付出更多的努力才能维持原来的水平（running to stand still）
Red Queen problem, named after the character that Alice encounters in Lewis Carroll’s Through the Looking-Glass. During the Red Queen’s race, the Queen tells Alice “It takes all the running you can do, to keep in the same place”
In the 20th century, we could access multiple untapped supergiant oil fields like the Ghawar Field in Saudi Arabia, that provided a ‘net energy’ ratio of 100:1. Today, we are often resorting to Tar Sands and Oil Shale for petroleum, which are sources with ‘net energy’ ratios beneath 6:1.