Category: Uncategorized

Distributed solar grid access fee axed in Arizona

By William Driscoll

Arizona regulators have repealed a grid access charge that applied only to customers with distributed solar.

“Under state and federal law, a utility may not discriminate” against customers with distributed solar, said a regulatory amendment that passed by a 3-2 vote.

Different treatment of solar customers must be justified “based on accurate data and consistently applied cost-allocation principles,” said the amendment, adding that the record in the rate case “contains no such evidence.”

The Solar Energy Industries Association, which filed over 300 pages of testimony in the rate case, “was able to prove that solar customers in Arizona pay their fair share of grid costs and do not introduce additional costs to other customers,” said Sara Birmingham with SEIA. The grid access charge had been approved by state regulators nearly a decade ago, she said.

Solar customers of Arizona Public Service contribute more to the utility’s cost recovery than non-solar residential customers served under two of the utility’s rate classes, tweeted Ben Inskeep with EQ Research.

The grid access fee was “making it harder for Arizona families and businesses to choose solar,” said Yara Marin with Vote Solar, which had filed over 200 pages of testimony.

The Arizona Corporation Commission amendment noted that “the recent Commission elimination of net metering for solar customers was in part intended to address a perceived cost shift from solar to non-solar customers.” The amendment added that “in that light,” the grid access charge “amounts to a penalty for customers who provide substantial public benefit in the form of private investments in local, pollution-free energy.”

Utility fees on solar have also been reversed in Kansas, Nevada and Massachusetts, said Inskeep.

Electricity storage in hot stones validated by $3.4 million investment

By William L. Driscoll

A long-duration thermal battery technology described to the California Energy Commission last December has gained credence from a Danish government investment.

The Danish Energy Agency will invest $3.4 million in a 10 MWh plant in Denmark to demonstrate the technology, which stores electricity as heat in small basalt stones. The system’s round-trip efficiency is projected to be 60%.

A U.S. project team aims to build a second demonstration project, twenty times larger, in the U.S.

Danish firm Stiesdal and its U.S.-based partner Magellan Stortech described the long-duration “GridScale” thermal battery system last December in a public workshop hosted by the California Energy Commission (CEC).

A thermal battery plant coupled with a solar farm could be configured to charge daily for 8 hours and discharge for 16 hours, the firms said. Or, because the hot stones would be stored in insulated tanks, the system could store energy for up to 10 days.

The two firms said they “look forward” to working with teams at the University of California Merced and the consulting firm E3 to “clarify the benefits that long-duration storage can provide,” as a follow-on to the CEC’s initial workshop on long duration storage scenarios.

The thermal battery system, already tested at 1:10 scale in Denmark, uses the principle of an electric heat pump to shift heat from cold pea-sized stones in one tank to hot stones in another tank, heating them up to 600 degrees C. The heat is later extracted at a constant temperature to drive one or more gas turbines to generate electricity. A modular design facilitates scaling, up to 1 GW capacity or larger.

As of December, Stiesdal and Magellan Stortech were exploring options for deploying a second and larger demonstration plant in the U.S., sized at 20 MW of 10-hour storage, or 200 MWh. The firms aimed for subsequent commercial-scale U.S. projects.

Advantages of the thermal battery system include the low cost of crushed stone, and the use of charging and discharging technologies that have been “applied for a century within other industries” and are well-suited for mass production, said Peder Riis Nickelsen, CEO of Stiesdal Storage Technologies.

NREL: Show true colors for the solar potential across the U.S.

By William L. Driscoll

Nearly all of the U.S. has at least 70% of the solar potential of land in the desert Southwest, according to government data. There is no dramatic drop-off in solar potential as you move away from the desert Southwest, as you would think from the federal map at left.

We need a new federal map to reflect solar’s true potential across the U.S.—such as the map at right, whose color scheme accurately reflects the data.

Images matter, because they shape public opinion. Someone who thinks their region has pitiful solar potential is unlikely to install rooftop solar. Solar installers working hard nationwide to transition our grid to renewables deserve support from the National Renewable Energy Laboratory, which publishes the map at left. NREL should update its map to replace its misleading colors with accurate colors.

For example, data from NREL’s key, at the bottom right of its map, show that global horizontal solar irradiance in the two northern bands is 70% of that in the two sunniest Southwest bands (4.00 kWh/m2/day versus 5.75 kWh/m2/day). That’s indicated by the moderately intense red colors at the top of the map at right, which was prepared by the author. But the pale yellows at the top of NREL’s map are nowhere close to 70% of the intensity of its colors for the Southwest.

NREL’s solar irradiance maps date back at least as far as 2009, when dramatizing the most promising regions for solar may have been appropriate. Back then, solar was expensive, and maximizing the revenue from every solar panel may have been an important consideration. But now that solar is inexpensive, it’s vital to see solar’s potential in every part of the country.

The map at right starts with pure red for the Southwestern band with the highest irradiance. The map incrementally adds more white, to create a less intense shade of red, for each lower-irradiance band, on a scale where zero irradiance would be represented by pure white. Because even the northernmost two bands have 70% of the irradiance of the far Southwestern band, their colors are deep pinkish reds that are about 70% as intense as pure red. And generally, the map appears red, because there’s substantial solar potential everywhere.

NREL is funded by taxpayers through the U.S. Department of Energy. NREL’s mission is to advance the science of renewable energy technologies, yet its map at left above is a funhouse mirror caricature of science. It’s time for NREL to fix this map.

As for the term “global horizontal solar irradiance,” that measure counts all solar radiation reaching the earth, whether directly from the sun or after passing through clouds.

Photoshop made this possible

To create the map at right, NREL’s map at left was first imported into Photoshop. The deep violet red in the lower left of NREL’s map was replaced with pure red, specified in Photoshop as R = 255, G = 0, B = 0 (RGB stands for red, green, blue).

This pure red color was used to represent 5.87 kWh/m2/day, because the key defines the deep violet red band as having global horizontal solar irradiance greater than or equal to 5.75 kWh/m2/day, and the other bands represent a range of 0.25 kWh/m2/day.

For the band next to the “maximum” band, 5.62 is the approximate midpoint of the range of 5.50 to 5.75. Thus, the ratio of the second band’s irradiance to the first band’s irradiance is 5.62/5.87, or 96%. In Photoshop, to select a shade of red that is 96% as intense as pure red, a color was selected that is 4% of the way from pure red to pure white. That color happens to be R = 255, G = 11, B = 11. Those values are based on the values for pure white (R = 255, G = 255, and B = 255), and the calculation that 11/255 is about 4%.

The same process was followed for each subsequent color band, using data from NREL’s key to transform each NREL color band into a “true color” that accurately reflects the NREL data.

How Biden could turn TVA toward clean energy—an interview with campaign leaders

By William Driscoll

Two leaders of a citizens movement calling on President Biden to transition TVA to clean energy describe their campaign, in this interview.

Biden can appoint six of the nine board members for the federally owned utility by May 2022, to fill vacancies and replace members whose terms expire. These appointments, subject to Senate confirmation, would achieve a board majority.

The new board would then need to engage with TVA’s decision-making, say the two campaign leaders, to reverse the utility’s current plans to invest in 1.5 gigawatts of new gas generation, and transition to clean energy.

Campaign coordinator Brianna Knisley of Appalachian Voices joined Daniel Tait, chief operating officer of Energy Alabama, to talk about the road ahead. The interview has been edited and condensed.

Q: Tell me about your campaign.

Brianna Knisley: The Tennessee Valley energy democracy movement formed out of a listening project in 2019, when we visited 13 communities in the TVA footprint to get a better understanding of what people wanted for their energy future, and how they want their public power system to work. We heard that people want a TVA that is more democratic, with a cleaner power supply, and that treats ratepayers in the valley fairly. TVA needs to have a target for zero emissions, and invest in energy efficiency, distributed generation and community solar.

We also want to see TVA strengthen its commitment to safe high-quality jobs. TVA has some work to do around protecting coal ash cleanup workers, and also ending harmful practices around contracting out good, full-time jobs.

TVA has operated more like a corporate investor-owned utility since 2005, when its board structure changed quite a bit. And we think TVA needs to get back to acting more like a public power provider, and one that is democratically controlled by ratepayers.

For the Tennessee Valley energy democracy movement, we use the term movement because it’s not a formal coalition. We don’t have groups formally signed on to a set of agreements. More than a dozen organizations participate—including Energy Alabama, Appalachian Voices, Statewide Organizing for Community Empowerment, and Tennessee Sunrise—as well as some grassroots and labor-focused groups, and also activists across the region. I serve as a co-convener, along with some other folks.

Q: What is the current TVA board’s stance on renewable energy?

Daniel Tait: Aside from a couple of board members that are relatively new—so we reserve judgment on those particular board members—the rest of the board members basically just defer almost everything to the management. The board has signed off on the destruction of energy efficiency programs, and small-scale renewable programs. The existing TVA board has definitely not shown any indication that it is willing to move aggressively on renewables or climate.

Q: Have you seen any signs that President Biden intends to appoint TVA board members who favor clean energy?

Daniel Tait: To meet the scale of the challenge we face as a nation, around the energy transition, really will take the Biden Administration being a little bit more aggressive than administrations have been in the past, including the Obama Administration, to be frank, about making sure that TVA’s board members are prioritized. So far, we haven’t really seen that out of the Biden Administration. We’d like to see more thought and aggressiveness in terms of the timeline from the Administration. This is a really important issue, with 1.5 gigawatts of new gas proposed from TVA, which is clearly in conflict with the Biden Administration’s executive order on net zero carbon emissions by 2035. You know, we need to act now. Having a TVA board that is willing and technically able to hold TVA management accountable is something we haven’t had. And we desperately will need new board members.

Brianna Knisley: The other priority we have is that we need TVA board members who come from environmental justice and racial justice backgrounds, who can represent labor interests, and unions that work at TVA. And, of course we need folks who can work towards climate justice as well. Historically the board has been mostly white; you see a lot of big business executives and folks that represent Chambers of Commerce. And, you know, we want to see folks with energy backgrounds and energy worker experience on the board as well.

Q: Can you say a bit more about TVA’s plans for new fossil or renewable generation?

Daniel Tait: Since Biden was sworn in, TVA has proposed nothing but new fossil fuel generation, which is not just the antithesis of the executive order, but also is a really bad economic, environmental, and social choice. It comes off as a kind of a direct challenge to the administration. They have a proposal out right now, for two 750-megawatt gas peaking plants, one in Kentucky, one in Alabama, for 1.5 gigawatts total.

This was particularly egregious, from my standpoint as a previous member of the committee that advised on TVA’s long-range resource plan, because when we went through that process, there was one run of the model where we said, let’s take off the restrictions on energy efficiency and demand response and see what happens. And lo and behold, when TVA’s model had those restrictions taken off, the model selected a lot more energy efficiency, which displaced gas. So that was pretty eye opening, that energy efficiency and demand response were the most cost-effective ways to make sure that TVA did not keep doubling down on fossil fuel infrastructure. And it’s also good for consumers in terms of lowering their bills.

Brianna Knisley: TVA also intends to prepare an environmental impact statement for advanced nuclear reactors in Oak Ridge, totaling up to 800 megawatts. They’re actually proposing a park that would contain one or more nuclear reactors.

Q: What about TVA’s announcement that it plans to add “up to 10 gigawatts” of solar power by 2040, and its resource plans generally?

Daniel Tait: Oh, absolutely. “Up to” is the operative phrase. They have been using that as a qualifier for some time, but they don’t have any concrete plans actually develop that much. We haven’t seen any board materials or budget materials showing that they’re actually putting their money where their mouth is on that stuff, but just kind of putting it in press releases. They have shuttered a few coal plants down in the last few years, but they still have a few running. Of course, now they’re trying to replace some older gas with new gas. So you know, it could make them cleaner, you know, but will it get them close to 100%? No.

In terms of what a clean energy grid looks like, for generating capacity and storage, frankly, we don’t really know the answer to that. The upcoming integrated resource plan will have to model some scenarios of net zero by 2050, at the absolute latest, and it will need to have other benchmarks like 80% by 2030, or 100% by 2035—different types of benchmarks like that to see what TVA’s grid would look like under those types of scenarios.

In Alabama, where I live, Alabama Power doesn’t even file an integrated resource plan; it just files a two-page summary and then hides all the rest. So, by comparison, TVA, which actually has an open process, looks pretty dang good. That said, as a previous member of the resource plan committee, I can say there’s a lot of power that TVA wields over the working group.

I think would be instructive to see what an independent third party could come up with, and you’re starting to see some other intervenors—like with Duke Energy in North Carolina—some of the intervenors ran their own integrated resource plan, and submitted that as part of their testimony in that docket, and it’s very different from what Duke is proposing. Something like that could be instructive here for TVA.

Q: What does the interest of Memphis in exiting TVA indicate about the potential for lower cost renewable generation in the TVA region?

Daniel Tait: It’s complex, but TVA’s high wholesale power costs are driven by lots of debt that it’s carrying from failed nuclear investments in the ‘70s and ‘80s, coal plants that it refuses to shutter, and historic under-investment in energy efficiency and demand response. These bad decisions and under-investment have driven the wholesale power cost to uncompetitive levels compared to many of its neighbors.

You’ve probably seen the studies that show hundreds of million dollars could be saved by the Memphis municipal utility, by leaving the TVA. It says there’s a lot of opportunity, right? TVA could put downward pressure on the wholesale power rate by doing a lot of things I just mentioned. Not only could it save that kind of money for Memphis, but all of the rest of the local power companies in the valley could also then get massive amounts of savings too—probably billions of dollars in savings. Brianna Knisley: We all just want to see TVA live up to the ideals that were espoused in the original TVA Act, and become the living lab that we all think it should be. TVA could be a model for how utilities can transition rapidly towards clean energy in a way that is equitable, and supports workers. TVA could definitely do that with the support of the federal government. There’s just a widespread disappointment that TVA has been resisting that transition for unknown reasons. TVA has the ability to do it.

‘Waze’ for power lines would unlock 500 GW of renewables projects

By William Driscoll

U.S. utilities could use three technologies to increase the utilization of transmission lines, enabling 500 GW of renewables projects to win interconnection approval, say industry veterans Jigar Shah and Rob Gramlich, in an op-ed published by Utility Dive.

Three transmission technologies have been implemented in “a matter of weeks and months” to increase transmission utilization in many parts of the world, say the authors. The technologies are shown in this image from the WATT Coalition:

Without these technologies, 500 GW of solar and wind projects “are currently stuck in transmission queues, forcing developers to wait as long as 900 days to get interconnected to the grid,” said the experts.

The Federal Energy Regulatory Commission (FERC) should create investment incentives for utilities to implement the advanced transmission technologies, wrote Shah, who is president of Generate Capital, and Gramlich, who is president of Grid Strategies and the point of contact for the WATT Coalition.

Without such incentives, utilities will favor new transmission lines, on which they can earn a guaranteed rate of return on the massive investments required. “Rather than encouraging electric utilities to spend more,” said Shah and Gramlich, “the incentive for grid-enhancing technologies must instead reward utilities for more efficiently using what we have already paid for.”

Thirteen U.S. Senators wrote to FERC last month, asking the commission to create performance-based incentives for utilities to improve transmission capacity and efficiency. They noted that the Energy Policy Act of 2005 directed FERC to “implement transmission rates that improve reliability and reduce the cost of power.” The Senators favor storage as transmission, in addition to the three technologies promoted by the WATT Coalition.

Grid operator Southwest Power Pool (SPP) has validated one of the three technologies, advanced topology, through a back-testing simulation of 20 actual instances of “congestion/overloads.” A joint presentation by SPP, The Brattle Group and Newgrid described advanced topology as “Waze for the transmission grid”–moving power along less-congested lines–with sample results shown in this diagram:

SPP found that if it had used advanced topology in the 20 cases studied, power flow would have been reduced on the constrained transmission line by an average of 26%, and by at least 10% in each case.

The U.S. Department of Energy described the technology of dynamic line ratings for transmission lines, by comparing it to the widely used static line ratings:

  • The maximum power flow capacity on a transmission line is limited by heating considerations, to maintain safe and reliable operating conditions. These static line ratings (SLRs) are usually calculated using conservative assumptions about the transmission-line operating environment, producing an inflexible constraint that does not take advantage of changing or favorable environmental conditions (e.g., wind cooling) that allow for greater transmission usage. DLR is a blanket term for the many different technologies and methodologies for determining conductor thermal ratings in a more-dynamic fashion using improved, more granular, or real-time data. At its core, DLR systems help system operators determine the prevailing current carrying capacity limits of transmission lines to relax constraints based on SLRs.

To describe the technology of advanced power flow control, the WATT Coalition draws a comparison with ordinary power flow control:

  • Power flow control is a set of technologies that push or pull power away from overloaded lines and onto underutilized corridors within the existing transmission network. Advanced power flow control provides this same function with advanced features such as the ability to be quickly deployed, easily scaled to meet the size of the need, or redeployed to new parts of the grid when no longer needed in the current location.

Members of the WATT Coalition include AmpacimonLineVision, IncLindsey ManufacturingNewGridSmartWires, and WindSim Americas Inc. The coalition’s acronym stands for “working for advanced transmission technology.”