Energy is neither created nor destroyed. Rather, it loses its potential to do work. Humans lower stores of potential when they want work done. A wood burning fire is an example. Fissioning a nucleus is another. Energy loss is usually associated with the outflow of heat.
Energy stores come in many shapes and sizes. As well, we have different methods of applying the energy’s potential. when it comes to providing energy, we aim for a method that provides more than the effort in making its provisions. We can represent this as a ratio. The following table shows some ratios.
|Source||R3 Energy Ratio.
|Input % of
|Held et al 1977||43||2.3|
|Quebec||Gagnon et al 2002||205||0.5|
|Nuclear (centrifuge enrichment)||see table 1.||59||1.7|
|PWR||Inst. Policy Science 1977*||46||2.2|
|BWR||Inst. Policy Science 1977*||43||2.3|
|BWR||Uchiyama et al 1991*||47||2.1|
|Nuclear (diffusion enrichment)||see table 1.||21||4.8|
|PWR/ BWR||Held et al 1977||20||5.0|
|PWR||Oak Ridge Assoc.Univ. 1976*||15.4||6.5|
|BWR||Oak Ridge Assoc.Univ. 1976*||16.4||6.1|
|BWR||Uchiyama et al 1991*||10.5||9.5|
|Uchiyama et al 1991*||16.8||6.0|
|unscrubbed||Gagnon et al 2002||7||14|
|Natural gas||– piped||Kivisto 2000||26||3.8|
|Natural gas||– piped 2000 km||Gagnon et al 2002||5||20|
|LNG||Uchiyama et al 1991*||5.6||17.9|
|LNG (57% capacity factor)||Uchiyama 1996||6||16.7|
|Solar||Held et al 1997||10.6||9.4|
|Solar PV||rooftop||Alsema 2003||12-10||8-10|
|amorphous silicon||Kivisto 2000||3.7||27|
|Wind||Resource Research Inst.1983*||12||8.3|
|Gagnon et al 2002||80||1.3|
|Aust Wind Energy Assn 2004||50||2.0|
* In IAEA 1994, TecDoc 753.
Source is here.
All these ratios come with lots of assumptions and considerations. Compare the above to the following table’s values to see this.
Heinberg in his book “The Party’s Over” provides similar ratios which he defines as net energy. His values (which he attributes to others) follow.
|Process||Energy Profit Ratio|
|Nonrenewable||Oil and gas (domestic wellhead, 1940s)||Discoveries > 100|
|Oil and gas (domestic wellhead, 1970s)||Production 23|
|Coal(mine mouth) 1950s||80|
|Coal(mine mouth) 1970s||30|
|Oil shale||0.7 to 13.3|
|Coal liquefication||0.5 to 8.2|
|Geopressured gas||1 to 5|
|Renewable||Ethanol (sugarcane)||0.8 to 1.7|
|Solar space heat, flat-plate collector||1.9|
|Electricity Production||Coal, US averagetd>||9|
|Nuclear (light-water reactor)||4.0|
|Solar, power tower||4.2|
However, these ratios only consider the application of energy by humans to obtain energy for humans. Precious little consideration or value gets considered for any loss of energy capture by autotrophs. A mine lays waste thousands of hectares and may take hundreds to thousands of years to return to a pristine state. The ratios don’t include this consideration.