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It can be rather misleading to to talk about renewable energy generation versus total energy usage. Most uses of fossil fuels are very inefficient. For instanc
by eigenspace 9mo ago
It can be rather misleading to to talk about renewable energy generation versus total energy usage.
Most uses of fossil fuels are very inefficient. For instance, when you step on the accelerator in your car, only around 30% of the energy in the fuel you use actually is being used to propel you forward. The majority of the energy is wasted as heat. In a power plant that's more like 70% being captured and going towards the goal (electricity generation).
Another large quantity of energy-usage is heating, and electrical heat-pumps can be around 3-5x more energy efficient at heating an enclosed space than combustion or resistive heating.
So while things like heating an transportation use a very large amount of energy, conquering them with renewables actually won't require that Europe installs 10x or whatever more wind and solar, since electrification also brings significant new efficiencies.
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If you want to compare renewables against the amount of fossil fuels being burnt, then it'd be a lot more representative if you calculate the amount of wind energy impacting a wind turbine blade, or the amount of energy in solar radiation incident on a solar panel. That's an easy way to inflate the renewable numbers by ~5x or whatever
- adrianN 9mo agoMost power plants are less than 50% efficient.
- eigenspace 9mo agoYeah, 70% is more or less a best-case scenario (unless you count systems for recovering and distributing waste heat, then it goes higher)
- pfdietz 9mo agoA gas-fired CC plant built today will have a LHV efficiency > 60%.
- adrianN 9mo agoThat is true, but I believe that most power plants are not modern combined cycle gas plants.
- owenversteeg 9mo agoI mostly agree. Certainly transportation is an obvious one. But of course there are still some losses; when you include all the losses in the system and cold weather you can easily get ~80% for EVs vs. ~30% for ICE cars. Heat pumps can be very efficient, but 5x more efficient than combustion/resistive heating (which is near 100%...) is not common in practice. 3x, sure, plenty of installations that get that or better in mild climates. That said, those are two pretty large items. If we reached 90% electrification on both it would be a pretty big win: Road transport represents ~26% of global energy use and all heating/cooling (industry, building, agriculture) represents ~50%.
- youngtaff 9mo ago> Road transport represents ~26% of global energy use Does that 26% include the energy that's involved to ship the fuel in tankers? Something like 50% of marine fuel usage is shipping fossil fuels around the world
- SECProto 9mo ago> Something like 50% of marine fuel usage is shipping fossil fuels around the world Note that marine shipping is extraordinarily fuel efficient (from a gCO2/(t*km) basis), so I doubt that it adds a lot on a per ton of fuel basis. We just ship a lot of fossil fuels. This [1] graph looks to be in the right ballpark from what i remember in school 15 years ago, i didn't verify it in depth but +- an order of magnitude better than the next best method is roughly right https://image2.slideserve.com/4166134/gco-2-t-km-of-freight-transport-modes-l.jpg https://image2.slideserve.com/4166134/gco-2-t-km-of-freight-...
- lambdaone 9mo agoEven though petroleum product shipping accounts for almost 40% of shipping, the surprising efficiency of ocean transport still means that it's not that big an energy cost; a single-digit percentage of the energy content of the shipped oil/gasoline. But even that is still worth saving - it's a few percent more benefit for electrification.
- grumbelbart 9mo agoExactly. It is in general (much) more efficient to burn natural gas in a power plant and use the electricity for heatpumps compared to simply burning gas at home for heating.
- m4rtink 9mo agoYeah, in combined cycle plants you burn the natural gas first in a gas turbine first, use the waste heat from that to boil water and run steam turbine. Then condense the steam using your district heating circuit. You can say this is 100% efficient as you make some electricity and the rest does house heating.
- eigenspace 9mo agoDefinitely not 100% efficient, but it can still hit a much higher efficiency than without the heat recovery
- nandomrumber 9mo ago100% efficient assuming a perfectly spherical combined cycle gas turbine with district heating circuit operating in a vacuum.
- m4rtink 9mo agoLet say all the loses provide heating for the power plant building itself. ;-)
- grumbelbart 9mo agoThe thing is that your home's heatpump has an efficiency of 300%-500%. So even if your power plant and power delivery only has say 50% gas-to-electricity-at-home, you are still looking at 150%-250% gas-to-heat-your-house efficiency.
- holowoodman 9mo ago> Most uses of fossil fuels are very inefficient. For instance, when you step on the accelerator in your car, only around 30% of the energy in the fuel you use actually is being used to propel you forward. The majority of the energy is wasted as heat. In a power plant that's more like 70% being captured and going towards the goal (electricity generation). Yes, but there are also future inefficient uses of renewables. E.g. when making iron, you heat the ore (iron oxides) with coke (refined sulfurless coal). The coke will provide extra heat and act as a reduction agent, separating the oxygen atoms from the iron oxides. Now you can do the same thing with hydrogen as the reduction agent to avoid producing CO2 and to avoid using fossil fuels. However, creating renewable hydrogen is atm only 30% efficient, storing and transporting it has losses. Even with possible improvements, that hydrogen will be a very inefficient and costly use of electricity, and at least half of it will always be wasted. So in terms of total energy usage, making those kinds of industrial processes use hydrogen, we will have to at least double our electricity output. And a lot of that doubling will be wasted because of the inefficiency of electrolysis, as opposed to directly using coal or natural gas.
- Borg3 9mo agoUh, can you provide any scientific papers that H2 can be used for Iron smelting? CO2 is very stable, even at high temperatures. Its hard to strip O2 from it (except photosintesis). Now, H2 itself is very violatile gas. When burn, it creates water. Water is not stable high temperatures. It become vapor and when temperature rise it can even break bond between H2 and O. So, papers or are you hallucinating?
- nasmorn 9mo agoThey are already building such plants. So I would assume they have a plan But here is a paper - only the title is German the main part is English https://pure.unileoben.ac.at/files/1851525/AC06514880n01vt.pdf https://pure.unileoben.ac.at/files/1851525/AC06514880n01vt.p...
- jijijijij 9mo agoAre you suggesting burning H2 will create water and enough energy to split the water in H2 and oxygen again, afterwards? That would be amazing news! https://en.wikipedia.org/wiki/Steelmaking#Hydrogen_direct_reduction https://en.wikipedia.org/wiki/Steelmaking#Hydrogen_direct_re...
- natmaka 9mo agoThere are quite good explanation published at https://ourworldindata.org/energy-definitions https://ourworldindata.org/energy-definitions and https://ourworldindata.org/energy-substitution-method https://ourworldindata.org/energy-substitution-method