Maybe, but we’ll need a little policy and alignment of incentives to make it work

This week’s blog is co-authored with Emilia Chojkiewicz and Amol Phadke

The United States needs to up its transmission game. Last fall the US DOE issued a study indicating that a high electrification and renewables generation future needs at least a doubling of the regional transmission capacity we currently have – by 2035. But we aren’t building nearly fast enough to get there. We’ve been expanding transmission capacity at a rate of one percent per year in the last decade. The DOE study suggests we need something closer to 7 percent per year. 

Meanwhile, by the start of 2023, developers had submitted applications to connect nearly 2,600 gigawatts of total generation and storage capacity to the grid, and those applications will sit in queues for years as transmission operators study what transmission upgrades, if any, are needed to accommodate new projects. There have been some heroic efforts on the part of FERC and transmission planners to help projects get out of these queues more quickly, but without much needed transmission upgrades, even if they get processed quickly, the huge majority of these projects will exit the queue through the failure door, rather than by getting built.

Source

A technology solution?

It may seem that building new transmission capacity and clearing the interconnection queue isn’t so much a technology problem as it is a societal one. EI blogger Lucas Davis called this “Transmission Impossible,” and his paper with Catie Hausman and Nancy Rose talks about challenges stemming from fragmented utilities, cost allocation, and siting and permitting. But in Mission Impossible, Tom Cruise saves the day with exploding gum, metal-eating foam and voice changers. Can’t we invent fun technologies and gadgets to resolve our transmission woes?

It turns out that some of these technologies do exist – though they’re not exactly Hollywood movie stuff. They’re often put in a broad category of ideas called grid enhancing technologies, or GETs. Some GETs involve changes to how the grid is operated, like dynamic line ratings, power flow controllers, and switching lines in and out. However there’s one idea that involves upgrading transmission to permanently increase its capacity. It begins with the humble transmission wire, (a.k.a., a conductor).

For obvious reasons, we want our transmission wires to be low in resistance. Copper would be a natural material to use if that was all we cared about. But it turns out that copper can’t support its own weight very well. Instead, the technology of choice over the last century has been aluminum – lightweight, strong, with relatively low resistance – with a steel core for added strength. See the figure on the left below to get an idea of what this looks like.

Source

But there’s a newer transmission technology that replaces that steel core with a composite, such as carbon fiber; see the figure on the right above. Composite cores are lighter and stronger, and that allows the conductor to use a different kind of aluminum with lower resistance. The real game changer with these advanced conductors is that they don’t sag as they get hot. That means they can handle more current flow – two times or more – than other technologies. 

The opportunity

In the US, these advanced conductors have mainly been used in niche applications, like river crossings with long spans between towers. But in other parts of the world, most notably Belgium and the Netherlands, utilities have started taking their existing transmission rights of way, scrapping the old conductors, and replacing them en masse with these advanced conductors. This process takes a matter of months, can often be done with a maintenance permit, and once the substations they’re connected to are upgraded, it doubles the capacity of the line. Although advanced conductors cost more than conventional ones, increasing capacity in this way costs less than half as much as building a new line, because the advanced conductors avoid the need to get access to new land (right of way, or ROW) and build new towers. See the figure below.

Source

Last December we and our co-authors published an EI working paper that asked the question: What if the US followed the lead of these other countries, and used advanced conductors in more than just niche applications? Could it make sense to reconductor much more than we are now? 

The answer is a full-throated yes. Our results, which used a modified version of NREL’s ReEDS capacity expansion model, indicate that advanced reconductoring could save the US $85 billion on generation and transmission combined by 2035. Importantly, we found that reconductoring enables more spending on transmission (since it can be deployed faster than new rights of way), and access to lower cost generation (for example, by making cheap midwestern wind more accessible).

There must be a catch, right?

You may be wondering: if it makes so much sense, why aren’t we doing it already? Last month our colleagues at GridLab and Energy Innovation published a policy report that investigates this question. 

Many of the barriers they identified echo Lucas’s barriers to conventional transmission expansion: Planning, permitting, institutions and incentives. But the scale of these problems is much more manageable than in the case of conventional transmission expansion. For example, a key planning barrier to advanced conductors is not having a workforce familiar with the technology. But as workforce development issues go, this one’s pretty easy to deal with. Advanced conductor manufacturers have outreach teams to train crews. Another example, related to permitting, is that environmental review can get triggered when companies want to reconductor, but that issue got resolved in a recent update to the National Environmental Policy Act.

The GridLab-Energy Innovation policy report also talked about policy solutions. Again, compared to conventional transmission capacity expansion, advanced reconductoring policy solutions tend to be much more tractable and concrete. For example, the Feds could develop investment tax credits to cover advanced reconductoring projects, and they could channel more IRA and Bipartisan Infrastructure Law funding toward the technology. State regulators like those in Montana can ensure that the full suite of benefits – including avoided costs of new transmission – are considered when advanced reconductoring is proposed by transmission builders.

In fact, one of the policy recommendations in the report has already been adopted by Biden et al, suggesting that advanced reconductoring policy can get developed at light speed. The report proposes setting a national target for increased transmission capacity by 2030. Just a few weeks after the report was released, the White House announced a target to upgrade 100,000 miles of transmission lines in the US in the next five years, citing advanced conductors as one of the key ways to achieve that upgrade. 

Transmission and generation tradeoffs

Our results show that assumptions about transmission – including how quickly it can be built and whether or not reconductoring will play a role – have important implications for what generation is best in a least-cost scenario. As we mentioned above, we found that by investing more into transmission (enabled by advanced reconductoring), a cheaper generation portfolio is possible. 

However, transmission and generation planning processes make it difficult to take advantage of these kinds of synergies between transmission and generation siting decisions. Transmission plans are often based on anticipated generation needs, rather than the other way around. This made sense in the days when generation build costs dominated the cost of new transmission, and when there was flexibility in where to put coal and gas plants. It’s no longer the right way to think with extremely low cost wind and solar. 

Planning really ought to trade off the cost to build new transmission capacity with the cost to build new generation capacity. This is starting to happen in California. For example, the CAISO’s Draft 2023-24 Transmission Plan highlights a process for coordination between the CPUC, CAISO and CEC on transmission and resource planning. This works as a starting point. 

However our results indicate there are benefits to re-stringing massive swaths of the US transmission system.  That won’t happen if we follow the current “piecemeal” planning process (FERC’s word, not ours). This suggests that planners need to consider a scenario with large-scale reconductoring, along with what generation resources make the most sense in that case, rather than in a case with incremental buildout of individual transmission projects. 

There are reasons for hope that more large-scale reconductoring could start happening soon. One is the White House announcement we mentioned above. There are also a number of active bills (e.g. here, and here) in California that aim to grease the skids for advanced reconductoring. And DOE’s GRIP program just received a slate of proposals to support transmission projects, and at least one of them included a request to support 400 miles of advanced reconductoring in California (full disclosure: we are participants in that proposal).

Fixing the interconnection queue?

It may be that we can leverage the rapid deployment and low cost of advanced reconductoring to directly address the interconnection queue. If transmission owners that serve substations and regions with a large number of projects in the queue upgrade their lines and substations now, they could recover the cost of reconductoring and substation upgrades with a flat fee ($/kW) charged to any project developers that connect there. Something similar has been happening in Sweden (brush up on your Swedish or turn on Google Translate for that link!) for years. In this case, network companies can opt for grid upgrades that are more expensive than the present need, get loans to pay for it, and pay off those loans from payments made by users in proportion to subsequent utilization.

 Reconductoring And, not Or

Advanced reconductoring isn’t a silver bullet. Though we are bullish on it, it’s important to note that our results showed that the US needs to keep building new transmission as well. There are also a number of unknowns about advanced reconductoring in the US that need more study, like stability of power flow on longer lines, managing contingencies, and when, and for how long, lines can be taken out of service to do the work (incredibly, a crew of line workers in Texas did a reconductoring project with live wires). There is room for researchers like us to work on these questions, but we’d like to see transmission planners and owners take them up as well.

Source link