so the goal is to transport renewable energy from the point of production (e.g. coastline for offshore wind) to the point of consumption (e.g. big factory 300 miles from the coast).
what is the cost of doing this? when comparing different technologies. i.e. you can just build a cable and transport the electricity through that, or you convert the energy into hydrogen at the point of production, then pipe that hydrogen gas through a pipeline to the point of consumption. many big consumers can naturally consume hydrogen instead of electric power anyways, for example large steel mills. they require power for heating and reduction, but in both cases, both power sources can be used (for reduction, electrolysis vs. chemical reduction).
it’s well-known that the LCOE (levelized cost of electricity) for solar and wind is around 6 ct/kWh (citation needed, i’m citing from memory). so what is the cost of transporting that electric power over 300 miles? according to the diagram, it’s 4 ct/kWh over 1000 miles, so probably 1.33 ct/kWh over 300 miles using wires. so it makes a small part of the cost.
meanwhile if you use hydrogen, you have around a 70% conversion+storage efficiency (electric power -> hydrogen, plus storing it in an underground cavern) (source: this paper and german wikipedia about hydrogen storage). so to produce 1 kWh hydrogen, you need 1.4 kWh electricity at the cost of 1.4 * 6 ct/kWh = 8.4 ct/kWh. transmitting it over the pipeline, meanwhile, costs almost nothing, as seen in the diagram.
so in summary, producing+storing+transmitting hydrogen is slightly more expensive than just producing+transmitting electric power, but that already includes the storage cost. for electric power, you need additional batteries which i’m too lazy to write about now. just to give you an idea.
We shouldn’t transport electricity long distances. It makes much more sense to set up more local production instead.
yeah i think the same thing. energy sources are critical infrastructure, like streets and housing. imagine if you had to drive 1000 km just to go from your house to your workplace. unimaginable
Which is another good argument for decentralising generation; lots of small- to medium-scale renewable generators distributed around the area in which power is consumed would require less transmission than a few huge generators (especially if they’re things people would rather not live near, like coal turbines or nuclear plants).
You know what costs even more? Burning fossil fuels. I suspect this little bar graph doesn’t take into account those costs.
I don’t get why materials for HVDC are so much higher than everything else. Towers and cables are relatively cheap, the substation hardware is not, but neither are pumping stations with all of the safety requirements.
Also why only 500kV when there are 1.2MV systems in the world. Not that it would make much difference since the bulk of the cost is down to materials.
I didn’t see the amortisation time in my quick skim through.
I know in NZ the compliance cost to get a pipeline through would kill any project that tried to do this.
Obviously leaks etc are ignored in this model, but they at a significant contributor to climate change.
At least with H2, leaks are not a direct driver of climate change (apart from wasting energy ofc). Environmental concerns are much less of a factor compared to gas/oil. I think the main concern is to get from electricity to H2 and back. There are approaches to go sunlight -> H2 more or less directly (SunHydrogen currently working on comercialization), but they sit at about 11% sun -> H2 yield, which is still way below normal solar panels (up to 30%). Electrolysis performs much worse iirc
electrolysis alone has 80% electric -> hydrogen conversion efficiency minimum, sometimes close to 100%. most solar panels have 20% sunlight -> electric efficiency. so total sunlight -> electric -> hydrogen efficiency is about 20% * 80% = 16%. which might not sound like a lot but remember there’s a ton of sunlight so wasting some doesn’t matter.
it’s more about the economic cost to describe how feasible something is.
If efficiency at point of use is faceted in, things get better for electric, bit not enough to bridge the divide.
Hydrogen is difficult to work with, massive compression or cryogenic temperatures. Metal embrittlement is a long term concern.
Hydrogen is difficult to work with, massive compression or cryogenic temperatures. Metal embrittlement is a long term concern.
that’s hearsay. there’s lots of studies about hydrogen pipeline / storage feasibility, such as the ones i’ve linked above. pls stop spreading misinformation.
No it isn’t.
Oil can be pumped at atmospheric pressure and temperature, it is a little easier to warm it a bit, but not a hard requirement. This is easy to work with.
Electricity is easy to work with, it will stay in the wires and can be switched on and off in milliseconds.
To work with hydrogen, you have to either compress it a lot, or liquefy it. Both have significant challenges.
For example I was working on a hydrogen pilot project, we were using 700 bar compressed hydrogen as the storage mechanism. Getting the compressed gas out of storage was always a pain in the arse, valves would freeze open causing control problems. Perhaps physically larger valving wouldn’t have this problem, but the cooling potential of expanding 700bar gas back to atmosphere is significant. Compressed hydrogen is an explosion risk independent of oxidiser, so you have a double explosion risk, first the compression explosion then the chemical reaction in atmosphere of a spark (likely) is generated by the first. There are a bunch of other issues with it, but these are major ones.
Cryogenic hydrogen has it’s own I issues. I’m not as familiar with it.
Saying hydrogen isn’t difficult to work with is just your lack of experience. Difficult is just engineering challenges, but hydrogen has some unique issues that other options don’t.
Why is DC power so much more expensive than pipelines?
Pipelines are absurdly efficient because moving liquid or gas through a pipe is absurdly efficient per kilogram per kilometer, and the energy density of fossil fuels is absurdly high.
A Tesla supercharger v4 can deliver 500 kW of power. BYD has launched chargers that can deliver 1000 kW (aka 1 MW) to a single car. Naturally, each kW of power is capable of delivering 1 kWh per hour.
What is the equivalent flow rate in gasoline? 1 gallon of gasoline contains the equivalent of 33.4 kWh (1 L contains 9 kWh). So 1000 kW would be the equivalent of 30 gallons per hour (110 L/hr), or 0.5 gallons (1.85 L) per minute. That’s 5% of the rate of a typical gasoline pump in the United States.
Plus exposed high voltage wires need to be maintained in weather and around vegetation, so they have high operating costs. Then there’s higher capital costs of making sure that there are transformers and safety equipment that step the voltage up and down and sync with the rest of the grid.
In the end, it really is that power lines aren’t capable of carrying nearly as much energy as the chemical fuels that flow through a pipe, so on a per joule/kwh basis, there’s less economy of scale from power lines.
One problem with that comparison is that, sure gasoline has a really high calorific value. Shame you put it in a machine with 20% efficiency.
I would think that the graph would be rather different had it been “last kilometer”? I’d expect to see electricity at the bottom there.
All those fuel stations you have to build and operate… And the energy losses to move your car to those fuel stations.
Indeed, this paper seems to calculate around the goal of making powerlines look costly by cutting it to a dedicated process step. If you look at it end-to-end process from production to consumption transportation, it very likely looks different
Yes, the numbers change for shorter distances. There’s some loss in loading up a fuel tank and driving it to the station. But again, the high energy storage capacity of chemical energy still makes a huge difference.
If a loaded semi gets 8 miles per gallon of diesel, then moving a tanker full of 10,000 gallons of gasoline 200 mile (320 km) s will burn 25 gallons of diesel in order to transport 10,000 gallons of gasoline. Even with less efficient trucks (let’s say 6 mpg for 33.3 gallons of diesel burned), it’s still pretty efficient in terms of “losses,” of about one third of one percent of the original volume of fuel consumed. Of course, diesel is more energy dense than gasoline, especially gasoline mixed with ethanol, so the efficiency might drop to 99.5% instead of 99.7%, but we’re still talking about a pretty fundamentally efficient operation.
The real efficiency gains of electricity over fossil fuel (or any chemical fuel) comes from the more efficient motors. An electric car that goes 3 miles (5 km) per kwh is the equivalent of going 100 miles per gallon (42 km/L) of gasoline. A heat pump that has 300% efficiency only needs to transmit 1/3 as much electrical energy as would have been necessary for bringing fuel to a combustion-based heater.
So if you start breaking it down by actual use case, you might be able to make some gains back to mitigate the higher cost of transporting electricity across large distances. But it still remains that all the other methods are very efficient, too.
Wow, that’s a lot of food for thought.
- joules for thought
Food energy tends to be measured in kcals though
Power transmission is hard.
The wire, the complex components, keeping it all in phase and steady and not exploding, the maintenance…
I cannot emphasize this enough. People tend to trivialize this when talking about remote production, but moving electricity long-distance is basically the hardest part. And pipes really are dead-simple in comparison.
It’s also why local production is so appealing.
I was aware conceptually that it’s really complicated, but where are the costs going? Is this due to labor costs? Material costs? something else? What makes it so expensive to build and to operate, especially compared to pipelines.
I am not a power engineer, but I do know the capital costs for the wire and components all along the way is massive. They’re complicated, and they require a lot of expensive (and probably carbon intensive) materials.
Basic physics dictates it. Its more complicated than small scale DC/AC current with negligible transmission time you’re likely thinking of.
Maintenance is a pain, too. HV wires (especially the crazy DC ones) are extremely, extremely dangerous and basically can’t be near anything.
I’m not sure about installation labor costs vs a pipeline though.
capital costs for the wire and components all along the way is massive
That’s true of pipelines, too. It’s just that the sheer quantity of energy contained in those chemical bonds of chemical fuel is massive, so amortizing the up-front capital costs across how much energy can actually move through that pipe or cable in its lifetime tends to favor a pipe full of chemical energy, on a per kWh (or per joule) basis.
They are also pretty lossy too right? Some percentage of the energy you are moving is lost to heat
Yes, though that’s true of other methods.
Another big factor is that its very inconvenient to buffer vs tanks on either end, for transmission breaks that take time to repair, uneven energy supply/demand and stuff like that. Or even just capacitance.
A big old tank of oil on either end is cheap.
I’m not trying to shill for hydrogen or anything (I don’t like hydrogen), but this is definitely an issue.
DC power is pretty much ready to use.
pipelines are raw material with an energy capacity of which a much lower percentage can be used due to conversion inefficiencies
Because DC is produced electricity, and it takes burning around 10x the joules or more of hydrocarbons to match that power
what is going on with those error bars
Wildly depends on location, I reckon
Am I missing something? Isn’t this why we use AC power over long distances?
No, DC is for long distances
Yeah I started reading up on it more once I got thinking about it. Looks like AC was easier in the past, which is probably why we’re standardized on it for local grids
yeah, AC won during the current wars in 1900, mostly because efficient transformers were only available for AC at the time.
nowadays DC is often used for high-power long-distance transport though.
interesting piece of trivia: In 2003ish, there was a major power outage across the northwestern US and much of eastern Canada. One major issue was that the grid became desynchronized so resynchronizing was a major problem they had to solve to bring the grid back up. The province of Quebec uses high voltage DC lines (and also massive amounts of hydroelectric power, but that’s a conversation for another day) so they didn’t have that same problem and had returned their power to normal long before the rest of the region.
No such thing as a DC transformer. Transformers rely on generating a changing magnetic field and for that you need AC.
well, technically, the term transformer refers to any device that converts the wave-form from one form to another. so a rectangle -> triangle converter would be a transformer.in most cases, though, it’s only used in the sense of “voltage converter”. and these exist for AC and DCnvm
No, a transformer is a thing invented by Michael Faraday that uses magnetic fields to move energy between sets of windings.
A “rectangle -> triangle converter” is an inverter, and that coupled with a transformer and rectifier would be a way of stepping down a DC voltage (but not the only way).
The more general term you’re looking for is a “converter”.
yeah huh what
i remember reading an article about this but i can’t find it anymore
nvm you’re right
I really like this post, it gets down to nitty gritty brass tacks and brings some data.
That’s usually the thing that gets me grumpy about such conversations, people don’t bother discussing the realities of actually doing the thing, they just trade feel good articles about how everything is fine.
One thing about the paper is, the cost of high voltage DC lines is likely assuming you’re on land. Bringing the energy in from sea could be even more expensive, since you need much more expensive equipment, the environment is brutal, repairs involve sending people and material into that environment, and I have a feeling but I don’t know, I think that the movement of the offshore wind turbines could be mechanically stressful on cables that are relatively safe up in the air only dealing with wind (and they still can cut right through insulators swinging in the wind and vibrating at 60hz)
What about Uranium? How expensive is that?
We talk energy transmission here. And it’s not that small-scale reactors are so common, cheap and safe that we can use uranium on the spot.
if raw material in the form of oil is on the chart, there’s no reason uranium can’t be
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