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I like this diagram from Volkswagen visualizing the energy loss at every step for hydrogen versus BEV: https://images.hgmsites.net/lrg/hydrogen-vs-electric--vo

I like this diagram from Volkswagen visualizing the energy loss at every step for hydrogen versus BEV: https://images.hgmsites.net/lrg/hydrogen-vs-electric--volkswagen_100740973_l.jpg https://images.hgmsites.net/lrg/hydrogen-vs-electric--volksw... This image (don't know the source), which includes oil and coal, is also a good visualization: https://i.imgur.com/Wuhnlvu.png https://i.imgur.com/Wuhnlvu.png Even simpler: https://pbs.twimg.com/media/DPkaz0nX4AAcr_v.jpg https://pbs.twimg.com/media/DPkaz0nX4AAcr_v.jpg

dehrmann 6y ago
How efficient is electrolysis compared to making hydrocarbons?
mongol 6y ago
I would like to have seen more elaboration on transmission losses in the power grid. For example, if we imagine solar cells in Sahara generating energy for Europe, is power grid transmission feasible or does hydrogen look better in comparison?
- sacred_numbers 6y ago
  The problem with generating power in the Sahara for use in Europe has little to do with transmission losses and much more to do with the capital cost of building high capacity power lines over thousands of kilometers. There's also the cost of protecting those lines, since they would have to pass through several different countries that are not always politically stable.
  - deltron3030 6y ago
    It could be an incentive for political stability in those regions if they benefit from it.
  - mongol 6y ago
    Good point. But that could also ve an argument for hydrogen?
- Gibbon1 6y ago
  I linked a paper talking about that. Losses are likely on the order of 5% per 1000km. I would think long distance transmission lines could transmit power both east and west which solves some of the time shifting issues. And south to north which solves some of the issue with low irradiance during the winter at high latitudes. AKA Germany would probably be better off investing solar farms in southern Spain and connecting via long distance transmission lines. Only 1600km or so. Also consider sunset is an hour later in south west Spain.
- peroporque 6y ago
  That's what DeserTec planned to do some time ago. Power line transmission would be possible, but political situations were too unstable, so the project for canceled.
dmckeon 6y ago
With regard to https://pbs.twimg.com/media/DPkaz0nX4AAcr_v.jpg https://pbs.twimg.com/media/DPkaz0nX4AAcr_v.jpg if the capture and separate elements can be decentralized, then distribution and one storage phase are eliminated. In other words, if a refueling station can do solar or wind capture and electrolysis on-site, the economics are better. This would be unlikely for stations in urban or high-density areas, but for rural and suburban locations it might be a win.
- jepler 6y ago
  Check my math: Say a fueling station needs to serve (only) 100 cars per day, providing 50kWh per car. That's 200kW average generation power needed. Ballpark, a 1 m2 solar panel can generate 200kWh/year, or 23W average. (quora answer, 2018). You need .. really? 9100 m2 of area, which is .91 hectare or 2.25 US acres. A 200kW per day (73000kWh/year) wind turbine might stand 25m tall. (uk wind energy report, 2014) Will these function in suburban to urban settings? Would they be accepted by the public? In the US, siting rules are a mess, but one example I found called for 2500 feet (760+m) distance to property line and 1.5 times turbine height to overhead utility lines. (NCSL, 2016) Given these fairly large size requirements, unless I slipped some decimal points, it doesn't seem likely to work out. https://www.quora.com/How-many-kWh-will-1-sq-meter-of-solar-panel-produce-in-1-year?share=1 https://www.quora.com/How-many-kWh-will-1-sq-meter-of-solar-... https://cdn.ymaws.com/www.renewableuk.com/resource/resmgr/Docs/small_medium_wind_strategy_r.pdf https://cdn.ymaws.com/www.renewableuk.com/resource/resmgr/Do... https://www.ncsl.org/research/energy/state-wind-energy-siting.aspx https://www.ncsl.org/research/energy/state-wind-energy-sitin...
  - tuatoru 6y ago
    This is the point (one of the points) that Vaclav Smil makes about renewables: abysmal energy density of production (in Watts/square meter: more like 'intensity' than 'density' to me). The only thing that beats oil is nuclear fission. With everything else, production takes up land that could be used for something else, or isn't being used for something else because it has problems such as distance or inhospitable climate or unfriendly (steep or unstable) terrain. All of which drive up maintenance costs or make the land also unusable for energy production. There are no good solutions apart from the one that coal companies astroturfed us into nearly banning in the 1960s.

dehrmann 6y ago

How efficient is electrolysis compared to making hydrocarbons?

mongol 6y ago

I would like to have seen more elaboration on transmission losses in the power grid. For example, if we imagine solar cells in Sahara generating energy for Europe, is power grid transmission feasible or does hydrogen look better in comparison?

sacred_numbers 6y ago
The problem with generating power in the Sahara for use in Europe has little to do with transmission losses and much more to do with the capital cost of building high capacity power lines over thousands of kilometers. There's also the cost of protecting those lines, since they would have to pass through several different countries that are not always politically stable.
- deltron3030 6y ago
  It could be an incentive for political stability in those regions if they benefit from it.
- mongol 6y ago
  Good point. But that could also ve an argument for hydrogen?
Gibbon1 6y ago
I linked a paper talking about that. Losses are likely on the order of 5% per 1000km. I would think long distance transmission lines could transmit power both east and west which solves some of the time shifting issues. And south to north which solves some of the issue with low irradiance during the winter at high latitudes. AKA Germany would probably be better off investing solar farms in southern Spain and connecting via long distance transmission lines. Only 1600km or so. Also consider sunset is an hour later in south west Spain.
peroporque 6y ago
That's what DeserTec planned to do some time ago. Power line transmission would be possible, but political situations were too unstable, so the project for canceled.

dmckeon 6y ago

With regard to https://pbs.twimg.com/media/DPkaz0nX4AAcr_v.jpg https://pbs.twimg.com/media/DPkaz0nX4AAcr_v.jpg if the capture and separate elements can be decentralized, then distribution and one storage phase are eliminated. In other words, if a refueling station can do solar or wind capture and electrolysis on-site, the economics are better. This would be unlikely for stations in urban or high-density areas, but for rural and suburban locations it might be a win.

jepler 6y ago
Check my math: Say a fueling station needs to serve (only) 100 cars per day, providing 50kWh per car. That's 200kW average generation power needed. Ballpark, a 1 m2 solar panel can generate 200kWh/year, or 23W average. (quora answer, 2018). You need .. really? 9100 m2 of area, which is .91 hectare or 2.25 US acres. A 200kW per day (73000kWh/year) wind turbine might stand 25m tall. (uk wind energy report, 2014) Will these function in suburban to urban settings? Would they be accepted by the public? In the US, siting rules are a mess, but one example I found called for 2500 feet (760+m) distance to property line and 1.5 times turbine height to overhead utility lines. (NCSL, 2016) Given these fairly large size requirements, unless I slipped some decimal points, it doesn't seem likely to work out. https://www.quora.com/How-many-kWh-will-1-sq-meter-of-solar-panel-produce-in-1-year?share=1 https://www.quora.com/How-many-kWh-will-1-sq-meter-of-solar-... https://cdn.ymaws.com/www.renewableuk.com/resource/resmgr/Docs/small_medium_wind_strategy_r.pdf https://cdn.ymaws.com/www.renewableuk.com/resource/resmgr/Do... https://www.ncsl.org/research/energy/state-wind-energy-siting.aspx https://www.ncsl.org/research/energy/state-wind-energy-sitin...
- tuatoru 6y ago
  This is the point (one of the points) that Vaclav Smil makes about renewables: abysmal energy density of production (in Watts/square meter: more like 'intensity' than 'density' to me). The only thing that beats oil is nuclear fission. With everything else, production takes up land that could be used for something else, or isn't being used for something else because it has problems such as distance or inhospitable climate or unfriendly (steep or unstable) terrain. All of which drive up maintenance costs or make the land also unusable for energy production. There are no good solutions apart from the one that coal companies astroturfed us into nearly banning in the 1960s.