(UPDATED, January 2014)
How much Fossil Fuel is needed for Solar Transition & Which one should be used?
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Let’s first be clear that solar transition must be parasitic on existing energy supplies, just as the industrial fossil fuel revolution was parasitic on biomass energy, so-called plant power, until it replaced the former supply with sufficient capacity. The higher the EROEI* value of the wind/solar technology used, the less unsustainable presently-used-energy is needed to effect the solar transition. Mainly because of its lower carbon emission footprint compared to coal, the preferred fossil fuel to make a solar transition is petroleum (oil and natural gas, but excluding tar sands, fracked natural gas, and dangerous drilling on deep water continental shelves). Just how much petroleum is needed in our preferred solar transition model to insure a steadily increasing global energy supply with a minimum 3.5 kilowatt/person globally, accompanied by an early phaseout of coal, nuclear, big damaging hydropower and most biofuels?
Recall this model has the following assumptions: conservative value of EROEI = 20, 20-30 year transition, and at its completion 2x the current global energy delivery is generated comprised of all wind/solar, no fossil fuel/nuclear/biofuels. We estimate that no more than 40% of the proven conventional reserves of petroleum (oil and natural gas, excluding tar sands and fracked gas reserves) is needed, roughly 7 ZJ. The latter requirement will be reduced as higher EROEI wind.solar technologies are developed and put in place in this transition.
Yes, at the culmination of this solar transition a global increase in energy would be delivered to the world not a decrease, with many countries in the global North such as the U.S. decreasing their wasteful consumption, while most of humanity in the global South get a significant increase. To reach the minimum 3.5 kilowatt/person now (7 billion people) requires a delivery equivalent to 25 Tera Watts, with the present delivery equal to 16 Tera Watts (Energy consumed = Power x Time, so just multiply 16 TW by 1 year to get the energy consumption per year, units TWyears). The factors impact on this estimate are discussed in our Report posted on solarutopia.org.
In a robust solar transition, generating progressively increasing global energy delivery over 25 years, with an EROEI value of wind/solar power equal to 25 (same as their lifetime in years) then a total of 18.5 ZJ is consumed, with RE-derived energy generating 54%, and industrial carbon sequestration energy requiring 5 to 20% of the total. This requirement would of course be reduced by the use of agriculturally-driven carbon sequestration into the soil.
Here is the function used for progressive phase-out of non-RE energy sources over the assumed 25 year transition period, with t being the time in years:
FF = 1 – 0.015 t – 0.001 t2 ; ∫FFdt from t = 0 to 25,
gives a non-RE energy sources equal to 15.1 times the present annual global energy consumption level (18 TW year = 0.57 ZJ) or 8.6 ZJ.
Smil (2008) cites Ahlbrandt et al. (2005), who estimated the proven conventional natural gas reserves equal to 7.24 ZJ (55% of 415 Tm3). With an assumed 1,354 bb for the proven conventional oil reserve (equivalent to 7.9 ZJ) this gives a total equal to 15.1 ZJ for proven conventional oil plus gas reserves (“petroleum”). Then the 8.6 ZJ for non-RE energy computed from our robust solar transition is equal to 57% of this proven petroleum reserves. (The ‘proven’ reserves cited do not include tar sands, oil shale or fracked gas). From Figure 2, Hansen et al. (2013), the total of “estimated” plus “recoverable resources” of conventional oil and gas can be computed, roughly equivalent to 26 ZJ (14 ZJ gas, 12 ZJ oil*). For this estimate, the 8.6 ZJ computed from our robust solar transition is equal to 33% of potential energy of recoverable conventional petroleum still in the crust. Since coal, nuclear power as well as hydropower and biofuels now contribute to global energy consumption, and will during their phase-out in a full transition to RE, the computed petroleum contribution is a maximum.
* Assumed values of 51.4 Gt CO2/ZJ for gas, 68 Gt CO2/ZJ for oil.
References cited:
Hansen et al., 2013, Assessing ‘‘Dangerous Climate Change’’: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature. PLOS ONE 8 (12) e81648.
Other references are given in Schwartzman and Schwartzman (2012), available for download on this website.
Aggressive energy conservation and rapid phaseout of coal use in energy-wasteful countries such as the U.S. is imperative, and must start in the very near future to begin radical reduction in carbon emissions. Further, as the solar transition proceeds, energy conservation in the gobal North would free up petroleum needed for rapid solar development in the global South. Oil rich countries in the Mid-East and South America (e.g., Venezuela) will be valuable partners in this solar transition by providing the needed petroleum. We are persuaded that this hopeful scenario requires global demilitarization a necessary condition for a global cooperative regime of transition. But if we wait too long without making a vigorous transition, then and only then will we likely face the gloom and doom scenario of Peak Oil and the virtually inevitable onset of catastrophic climate change, barring near future revolutionary solar technologies with much higher EROEIs. Nevertheless, carbon sequestration powered by agroecologies and solar power is imperative, and must start asap to have any hope of preventing the onset of catastrophic climate change (“C3″). The longer the excess carbon dioxide remains in the atmosphere the more likely the tipping points for C3 will be reached, therefore radical and early cuts in carbon emissions and carbon sequestration go hand in hand. And now we may have only 5 years left for global carbon emissions to peak, to be followed by radical cuts (“World headed for irreversible climate change in five years, IEA warns If fossil fuel infrastructure is not rapidly changed, the world will ‘lose for ever’ the chance to avoid dangerous climate change” , Fiona Harvey,guardian.co.uk, November 9, 2011).
* EROEI is the Energy return over energy invested ratio, i.e., how much energy does the technology such as a photovoltaic array or wind turbine generate in its usable lifetime divided by the energy needed to construct it and maintain it.
By, David Schwartzman