The most obvious sources are natural gas and coal. Over the short term, coal is relatively abundant. But, coal is not oil and significantly increased production presents serious collateral problems. To see how the coming decline in the world production of oil and natural gas will impact our energy future, we must look at how they fit into the energy mix. Today, we get our energy from a variety of sources.
Unconventional oil is heavy oil, tar sand, and shale oil.
These data are shown in Table 1, columns 1 and 2. From the above percentages, we can calculate the Gboe for the other sources as shown in column 3. However, the amount of energy in a barrel of oil is larger than the equivalent weight of the other energy sources. Column 4 lists the energy for an equivalently equal weight of the source relative to a barrel of conventional oil. The energy equivalent for Nuclear and Hydro electric is arbitrarily set to 1.0 because there is no direct conversion.