Will Pipelines Be Repurposed For HVDC Transmission?

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This query is requested usually of me lately. In any case, high-voltage direct present (HVDC) is the brand new pipeline, doesn’t care if it’s run underwater, underground or by way of a metal pipe, and the hundreds of thousands of kilometers of pipelines on this planet are going to be decommissioned at an accelerating price over the approaching a long time.

Additional, at the least within the developed world, transmission towers get as a lot NIMBY pushback as wind generators, and in contrast to wind generators should march by way of cities and cities in lots of instances. Then there’s the well being paranoia of the individuals who suppose that electromagnetic spectrum radiation is dangerous to their household’s well being as a result of they’re incompetent to evaluate medical proof.

The mixture leads folks studying items equivalent to my latest Forbes article on the topic to ask, “Why don’t we run HVDC traces by way of the pipelines! Out of sight, out of thoughts, present conduit. Win win!”

Properly, not so quick. HVDC is costlier than high-voltage alternating present (HVAC) transmission nonetheless. As a result of its magnetic fields aren’t oscillating back and forth 50 to 60 instances a second however staying steady, they work together so much much less with water and soil. As such, the breakeven level for HVDC being cheaper than HVAC is simply about 50 kilometers undersea, whereas it’s 800 kilometers on overhead traces. HVAC losses could be decreased by rising voltage on overhead traces, however not underwater.

That stated, there’s an rising medium voltage direct present (MVDC) set of applied sciences from companies like Hitachi ABB and Siemens. HVDC runs from 100 kilovolts (kV) to 800 kV often, and there are UHVDC deployments that run at 1,100 kV. MVDC is meant to run at 10 to 33 kV, extra within the vary of the first distribution grid, not the transmission grid.

A 2021 research by a French analysis crew underneath a grant and supervision from the French Nationwide Analysis Company discovered that breakeven for medium voltage alternating present could possibly be underneath 10 kilometers to a couple dozen kilometers. Use instances the place MVDC is being proposed embrace offshore wind farms, massive and inherently direct present photo voltaic farms and electrification of railways.

A lot of the worth of this may be ascribed to the comparatively new direct present transmission know-how of voltage supply converter (VSC) AC to DC conversion. It recreates the sine wave of alternating present in tiny pixelated steps which are tremendous sufficient to be indistinguishable to the analog HVAC grid. With that new skill, it’s attainable to supply extra voltage and frequency management to native distribution grids through MVDC. One UK instance, the Angle DC MVAC to MVDC improve mission, is anticipated to extend delivered electrical energy throughout the traces by 23%.

That VSC know-how and its predecessor line commutated converter (LCC) do carry losses with them of about 2% of the electrical energy transformed by way of them, therefore the gap primarily based break even level. I grew to become conscious of the fabric whereas struggling to search out knowledge on how a lot HVDC there was globally and the place it was going. RTE Worldwide publishes a month-to-month snapshot of HVDC globally, however just for the VSC aspect. Wikipedia has a VSC and LCC record, but it surely’s Wikipedia. I assume the worldwide interconnection company China arrange underneath UN provenance, GEIDCO, with its 140 or so member international locations has an entire record, but it surely’s personal.

Cornelis Plet, head of the ability methods advisory follow at DNV helped me perceive this house higher. Earlier than his present function, the place he spends quite a lot of time consulting associated to HVDC, he was international follow lead for HVDC for a similar agency. A lot of his profession since his PhD in energy electronics and energy methods from Imperial School within the UK has been centered on this know-how, so it was nice to take a seat down with him for 90 minutes. The couple of podcasts that resulted from that can be reside in January on Redefining Vitality – Tech, so subscribe now in case you are interested by deeply nerdy conversations about the place the world is definitely going (and why so many individuals appear to not perceive or refuse to know the place it’s going). Plet too has a DNV confidential and extra full record.

After I analysed the place HVDC was and wasn’t, one of many issues that leapt out at me from Europe’s deployment was what number of segments of HVDC transmission routes have been underground. Usually, HVDC would come ashore from wind farms or UK interconnectors, run above floor for some time, after which dive underground, or vice versa. Given the extra prices of burying transmission or any electrical traces, clearly there was a requirement or constraint being met. To be clear, burying electrical infrastructure is way more prevalent in Europe than in North America, a part of the rationale why their grid is way more immune to disruption.

As for pipelines, the period of shifting molecules for power is coming to an finish. Clearly we aren’t going to be shifting oil, pure fuel, diesel and gasoline lengthy distances by way of pipelines to anyplace close to the identical extent. Peak demand for coal, oil and fuel are this decade per Fatih Birol, government director of the Worldwide Vitality Agence, and China’s large refiner and distributor Sinopec introduced that peak gasoline demand in that nation had already been reached. After this, the decline, and it will likely be way more fast than the oil and fuel trade needs to imagine. It received’t, nonetheless, be instantaneous, and the speed will range by geography. Some pipelines can have longer lifetimes, even at diminishing volumes, for longer, whereas others will grow to be uneconomic and shut down sooner.

For instance, I contemplate the probability that Canada’s Trans Mountain Pipeline can be bankrupt and defunct by 2040 to be very excessive. The properly over C$30 billion spent on tripling it should have been wasted. The mixture of peak oil demand and elevated prices of low-carbon hydrogen important for hydrocracking, hydrotreating and desulfurizating Alberta’s heavy, high-sulfur crude will improve the standard low cost and knock if off the market first. The distribution value low cost the Trans Mountain Pipeline was theoretically going to have addressed received’t be helped due to the development funds explosion, solely small AFRAMax tankers can get into the Port of Vancouver, and China received’t have an interest because it quickly strikes away from oil for floor transportation and inland water delivery.

As I famous in 2022 when commenting on the varied weak research that purported to point out that shifting hydrogen by way of pipelines was extra environment friendly with greater power transmission, all of them made a number of widespread errors. They drew the system boundaries on the finish of the pipelines versus extra broadly, assuming that there could be very massive quantities of low-carbon hydrogen the place the pipeline began, one thing solely true if the supply is fossil hydrogen. They assumed very low cost hydrogen, one thing which is more and more obvious even to hydrogen for power proponents isn’t going to be a factor. They made the first power fallacy, assuming that the entire gigajoules of warmth within the hydrogen have been equally helpful to the MWh of electrical energy within the cables, when that’s solely true for warmth and never for any of the opposite myriad issues we use power for like transportation. Even at that, they ignored warmth pumps which may’t be run with hydrogen. They ignored the comparatively low effectivity of turning electrical energy into hydrogen. They usually tended to downplay hydrogen pipeline compression prices.

So we’ve a confluence of applied sciences. We have now a declining pipeline trade with a bunch of to-be-abandoned belongings, each underwater and underground. We have now a rising demand for HVDC and maybe MVDC transmission. We have now opposition to ugly overhead transmission traces which is usually as a result of individuals who have their hearts in the precise place, suppose globally and resist every little thing domestically.

This leads lots of people to ask me and others, why not run the HVDC by way of the pipelines?

My reply up till this text has been:

I really want to write down a strong reply to this. However till then, the 800 km break even distance overland and the relative lack of pipelines operating between electrical energy technology and demand sources mix to make it unlikely to pencil out generally.

And so, the fuller reply.

There’s little probability of repurposing offshore pipelines and no use. HVDC is trenched into the underside of the ocean when anyplace close to shore, and that is undoubtedly cheaper than feeding a cable right into a pipeline and attempting to pull it by way of.

Onshore, pipelines hardly ever run from massive penetrations of latest technology on to facilities of electrical energy demand. There are exceptions with the North Sea wind and North Sea pure fuel extraction, however globally huge wind and photo voltaic farms and hydroelectric dams are typically situated in locations extra distant from oil and fuel fields. The identical drawback of getting numerous low-carbon hydrogen conveniently situated on the mouth of a pipeline to place into it applies to inexperienced electrons.

Subsequent up is the problem of operating heavy, thick and comparatively unbending cables by way of a whole bunch of kilometers of pipeline. HVDC cables run from 30 kg to 60 kg per meter. That signifies that an 800 kilometer cable has a complete weight of 24,000 to 48,000 metric tons. Attempting to drag segments of that by way of a pipeline is a excessive power, excessive friction job. HVDC transmission cables have a most pulling drive that they will stand up to of round 20 tons, however that features not simply the load of the cable but in addition the quickly rising friction with distance. It might require digging up pipeline segments at frequent intervals and at a sure level that will get costly.

Pipelines are inclined to have quite a lot of sharp bends in them. Gases and liquids go round corners a lot better than HVDC cables, which have a minimal turning radius of 1.5 to 2 meters. Pipeline thermal enlargement loops have three sharp bends in a number of meters to allow the pipeline to develop and contract with warmth and chilly with out destroying itself, or at the least not rapidly. These enlargement loops would nonetheless be required if pipelines are repurposed as HVDC conduit, however they must be ripped out and changed with gentler curves, ones calculated to not lower their radius to the purpose of breaking the cable.

Lastly, the necessity for transmission is generally discontiguous with the sunsetting of pipelines. We want quite a lot of transmission within the subsequent twenty years to ensure that pipelines to be sundown within the 2030s by way of 2050s. Pipelines that might pencil out if empty typically received’t be empty when the transmission run is required to maneuver ahead.

The reply adjustments considerably for MVDC transmission. The distances are a lot shorter. The MVDC cables are thinner and extra flexible. The pipelines are additionally distribution pipelines which have come and gone for many years. As one correspondent famous, the Netherlands repurposed some small pipelines for fiber optic runs and milk delivery. There are over 5 million kilometers of pipelines within the USA, and plenty of of them aren’t huge transmission pipelines. It’s extra doubtless as MVDC progresses that reusing some smaller pipelines will make sense. The enlargement loops would doubtless nonetheless require reengineering, however there are fewer on tiny pipelines than massive ones, so the issue could possibly be averted extra simply.

There’s one other potential use case, though I believe it’s much less doubtless as properly. There’s nothing technical that prohibits operating an HVDC line by way of a giant pure fuel transmission line that’s working. It might cut back the amount of the usually one meter diameter pipeline barely, by about 2% within the instance I simply labored out for the Baltic Pipe and a 1,000 MW HVDC cable (if my numbers are appropriate), however radically will increase power carrying capability and future proofs the pipeline. The place that pencils out, one thing attainable within the North Sea to central Europe hall, it’s price . Nevertheless it’s unlikely as pipeline builders and operators are preventing a rearguard motion in opposition to transmission and the loss of life of their enterprise mannequin. It doesn’t strike me as one thing that they’d willingly embrace, however would should be compelled into, with a lot governmental cash for his or her ‘losses’ because the pipeline is reengineered.

One other correspondent urged that it wasn’t the pipelines themselves that could possibly be repurposed, however their proper of how. That’s tremendous when they’re above floor, however the majority of pipelines are buried to provide them extra safety from all kinds of pure and human-caused injury. It doesn’t assist a lot when they’re buried in landslide and flooding susceptible areas, one thing the residents of Satartia, Mississippi found in near the worst attainable approach a few years in the past. A carbon dioxide pipeline carrying liquified CO2 ran afoul of heavy rains and land slides and ruptured explosively. The CO2 instantly flashed to fuel and because it’s heavier than the air, pooled in low-lying areas till it subtle naturally. Earlier than that occurred, dozens of individuals have been in convulsions on the bottom, a few hundred have been evacuated and inner combustion emergency automobiles couldn’t get near the victims as a result of they want oxygen too. It’s doubtless that the Satartia residents who have been most impacted will endure some long run organ and mind injury.

The bigger level is that pipelines go underneath issues and don’t have rights of approach in the identical approach that roads or railroads do. As such, repurposing the precise of approach is much less attainable.

And to be clear, after I had the briefest model of this dialog with Jesse Jenkins, Princeton Andlinger Heart assistant professor and deep power analyst, on that social media platform that’s collapsing and flailing a number of months in the past, he was extra optimistic than I used to be. As he identified, there’s an terrible lot of pipeline that we’ve buried up to now, over 5 million kilometers within the USA alone. A few of it will likely be in a position to be repurposed.

All in all, I believe it’s doubtless we’ll see some pipelines repurposed for MVDC for distances of some tens of kilometers, however suppose it’s unlikely we’ll see HVDC in a couple of or two pipelines. The choice ought to be included in transmission routing eventualities nonetheless, and investigated. And to be clear, this can be a tough first rules with massive error bars. If somebody is actively working to repurpose a pipeline for transmission, please attain out to let me know. That I’m unaware of it doesn’t imply it isn’t occurring.