3 ms·

Going down from a fantastically high return to a slightly less fantastically high return.

epistasis 10y ago
Yes, but it's going to continue to go down. According to Wikipedia [1] EROI Fuel ---- ---- 35.0 Oil imports 1990 18.0 Oil imports 2005 12.0 Oil imports 2007 6.8 Photovoltaic (wikipedia) 14.4 Photovoltaic [2] (from recent analysis of post-2008 data) The trend lines are clear and stark. The technologies for photovoltaic, wind turbines, and for fossil fuel extraction are all changing. It's certainly not the case that fossil fuels will disappear, but over the coming decades the sector will shrink dramatically due to market forces; investments will plummet. And once you start looking at the slow and steady pace of improvement in storage technologies, it looks highly possible that around 2025-2030, only specialized energy applications ever make new investments in fossil fuel based technologies. And that's without accounting for the negative externalities that fossil fuel users (all of us) make everybody else subsidize. Existing infrastructure will continue as long as its economical, of course, but there's most definitely a huge turning point around the corner in energy technology. [1] https://en.wikipedia.org/wiki/Energy_returned_on_energy_invested https://en.wikipedia.org/wiki/Energy_returned_on_energy_inve... [2] https://www.researchgate.net/publication/311170056_Solar-PV_energy_payback_and_net_energy_Meta-assessment_of_study_quality_reproducibility_and_results_harmonization https://www.researchgate.net/publication/311170056_Solar-PV_...
- ZeroGravitas 10y ago
  I believe those EROI numbers also don't include converting the energy into the useful output that you need and so are a a pointless apple-to-oranges comparison PV output is electricity already, to get electricity from coal you'd need to throw away 2/3rds of the energy as heat, about half for gas, reducing their EROI by that factor in a correct comparison. So if it's electricity you want then PV is already winning over fossil fuels I think. Similarly, for powering cars with gasoline they're not as efficient in converting that energy "well-to-wheel" as EVs, as the losses in battery storage and electric motors are much smaller, giving you a "miles driven return on energy input" measure about 3x higher for a PV charged car vs ICE. You can avoid the generation loss on natural gas by piping to the home and burning it directly for heat in areas that need heat, getting close to 100% efficiency with modern central heating systems, but then in those same situations you can use an electric heat pump and get 3-500% efficiency, since you're only moving the heat around, not generating it.
  - planteen 10y ago
    Don't heat pumps only work in temperate climates though? The low in Denver tomorrow is going to be 7 below...
    - philipkglass 10y ago
      At very low temperatures an air source heat pump does not have an advantage over simple resistance heating. But -7 F is not too cold for leading edge ASHP technology (or rather, this was about the leading edge 5 years ago): http://www.franklinenergy.com/wp-content/uploads/2014/10/AirSource-Heat-Pump-Efficiency-Gains-2011.pdf http://www.franklinenergy.com/wp-content/uploads/2014/10/Air... "Independent research has verified the ability of air source heat pumps to maintain energy efficiency well above other electric heating systems, with coefficients of performance (COP) of between 2 to 3, in temperatures as low as -15⁰ F. Multiple manufacturers have developed ASHPs designed for cold climate operation, incorporating features such as two-stage compressors and advanced defrost capabilities. Where data is available to evaluate the energy savings impacts of [Western Minnesota] customers moving from less efficient electric heating systems, the energy savings associated with the heating demand served by the hybrid ASHP systems is found to be in the range from 10% to more than 40%, with median savings of around 22%." It looks like the Western Minnesota region where they ran this trial has colder winters than Denver, so Denver-area results would be even better. The best air source heat pumps should be able to save energy over resistance heating for the vast majority of American households. They will also save energy over direct combustion of natural gas in a household furnace if the natural gas is instead burned in a combined cycle electrical plant. They will not reduce energy consumption or emissions vs. a home natural gas furnace if your winter-time grid electricity mix has a substantial coal component.
      - Gravityloss 10y ago
        for climates with colder winters, you can get high efficiency with ground heat pumps instead. It costs more to install since you have to drill a borehole, but the efficiency doesn't drop with colder weather.

Yes, but it's going to continue to go down. According to Wikipedia [1] EROI Fuel ---- ---- 35.0 Oil imports 1990 18.0 Oil imports 2005 12.0 Oil imports 2007 6.8 Photovoltaic (wikipedia) 14.4 Photovoltaic [2] (from recent analysis of post-2008 data) The trend lines are clear and stark. The technologies for photovoltaic, wind turbines, and for fossil fuel extraction are all changing. It's certainly not the case that fossil fuels will disappear, but over the coming decades the sector will shrink dramatically due to market forces; investments will plummet. And once you start looking at the slow and steady pace of improvement in storage technologies, it looks highly possible that around 2025-2030, only specialized energy applications ever make new investments in fossil fuel based technologies. And that's without accounting for the negative externalities that fossil fuel users (all of us) make everybody else subsidize. Existing infrastructure will continue as long as its economical, of course, but there's most definitely a huge turning point around the corner in energy technology. [1] https://en.wikipedia.org/wiki/Energy_returned_on_energy_invested https://en.wikipedia.org/wiki/Energy_returned_on_energy_inve... [2] https://www.researchgate.net/publication/311170056_Solar-PV_energy_payback_and_net_energy_Meta-assessment_of_study_quality_reproducibility_and_results_harmonization https://www.researchgate.net/publication/311170056_Solar-PV_...

ZeroGravitas 10y ago
I believe those EROI numbers also don't include converting the energy into the useful output that you need and so are a a pointless apple-to-oranges comparison PV output is electricity already, to get electricity from coal you'd need to throw away 2/3rds of the energy as heat, about half for gas, reducing their EROI by that factor in a correct comparison. So if it's electricity you want then PV is already winning over fossil fuels I think. Similarly, for powering cars with gasoline they're not as efficient in converting that energy "well-to-wheel" as EVs, as the losses in battery storage and electric motors are much smaller, giving you a "miles driven return on energy input" measure about 3x higher for a PV charged car vs ICE. You can avoid the generation loss on natural gas by piping to the home and burning it directly for heat in areas that need heat, getting close to 100% efficiency with modern central heating systems, but then in those same situations you can use an electric heat pump and get 3-500% efficiency, since you're only moving the heat around, not generating it.
- planteen 10y ago
  Don't heat pumps only work in temperate climates though? The low in Denver tomorrow is going to be 7 below...
  - philipkglass 10y ago
    At very low temperatures an air source heat pump does not have an advantage over simple resistance heating. But -7 F is not too cold for leading edge ASHP technology (or rather, this was about the leading edge 5 years ago): http://www.franklinenergy.com/wp-content/uploads/2014/10/AirSource-Heat-Pump-Efficiency-Gains-2011.pdf http://www.franklinenergy.com/wp-content/uploads/2014/10/Air... "Independent research has verified the ability of air source heat pumps to maintain energy efficiency well above other electric heating systems, with coefficients of performance (COP) of between 2 to 3, in temperatures as low as -15⁰ F. Multiple manufacturers have developed ASHPs designed for cold climate operation, incorporating features such as two-stage compressors and advanced defrost capabilities. Where data is available to evaluate the energy savings impacts of [Western Minnesota] customers moving from less efficient electric heating systems, the energy savings associated with the heating demand served by the hybrid ASHP systems is found to be in the range from 10% to more than 40%, with median savings of around 22%." It looks like the Western Minnesota region where they ran this trial has colder winters than Denver, so Denver-area results would be even better. The best air source heat pumps should be able to save energy over resistance heating for the vast majority of American households. They will also save energy over direct combustion of natural gas in a household furnace if the natural gas is instead burned in a combined cycle electrical plant. They will not reduce energy consumption or emissions vs. a home natural gas furnace if your winter-time grid electricity mix has a substantial coal component.
    - Gravityloss 10y ago
      for climates with colder winters, you can get high efficiency with ground heat pumps instead. It costs more to install since you have to drill a borehole, but the efficiency doesn't drop with colder weather.