Banding Together: How Aggregation Helps Cities Buy Renewables at Scale
By Yuning Liu & Mia Reback
In March 2021, 24 local governments in Maryland joined together on a plan to purchase enough renewable energy to power more than 246,000 homes a year. They did this by issuing a joint request for proposal (RFP) through the Baltimore Regional Cooperative Purchasing Committee (BRCPC) to seek a supply of up to 240,000 MWh of renewable energy starting in 2022. This large-scale transaction was made possible by an energy procurement approach known as energy aggregation, which is a way for two or more buyers to purchase electricity from a utility-scale generation facility.
According to the new Intergovernmental Panel on Climate Change (IPCC) report, greenhouse gas emissions (GHGs) must peak within four years to limit global warming to 1.5°C, and cities have a critical role to play in meeting that target. Aggregation can be a powerful way for cities to rapidly increase their renewable energy and help decarbonize local economies at the necessary speed and scale. Yet most cities have not pursued aggregation due to an inadequate understanding of its novel deal structure and a lack of tools and resources to help streamline the process.
Aggregation can be a powerful way for cities to rapidly increase their renewable energy and help decarbonize local economies at the necessary speed and scale.
To help cities overcome these barriers, last year the American Cities Climate Challenge Renewables Accelerator, an initiative co-led by RMI and World Resources Institute, began organizing a Large-Scale Renewables Aggregation Cohort. This cohort provided technical assistance to more than 30 organizations, including the BRCP. A second iteration of the cohort is now underway with a new group of organizations. In addition, a newly released RMI report, Procuring Large-Scale Renewables through Aggregation: A Guide for Local Governments aims to help more cities understand and pursue aggregation.
As more and more cities take actions to decarbonize the electricity system, aggregation will be an increasingly important option that can provide buyers with several advantages, such as opening doors for smaller cities, creating positive network effects, and unlocking more cost savings.
Enabling Smaller Buyers to Access Large-Scale Projects
Aggregation can enable participation from smaller cities that, on their own, are not able to purchase enough electricity to warrant the attention from developers. This is particularly important for smaller communities with 100 percent renewable energy goals, as most municipalities cannot supply 100 percent of their electricity needs with on-site solar generation alone. Therefore, a utility-scale, off-site procurement will be an essential component of many smaller buyers’ decarbonization strategy.
One instance of a small buyer accessing large-scale renewables projects is a 25 MW joint solar purchase completed by MIT, Boston Medical Center (BMC), and Post Office Square (POS) in 2016. In this aggregated deal, MIT committed to buy 73 percent of the power generated by the new array, with BMC purchasing 26 percent and POS purchasing the remainder.
“Entering into a renewable power purchase agreement was our next step, but our consumption is too small to do it alone,” said Pamela Messenger, general manager of Friends of POS. “It is exciting to join forces with two industry leaders, allowing us to mitigate 100 percent of our electricity footprint.”
Similarly, other smaller local governments have also used aggregation to gain access, such as five local governments in Maine. They teamed up for the state’s first multi-town renewables project, a 4 MW solar array, which provides climate benefits equivalent to more than 4,000 acres of forests.
Without pooling the electricity demand with other buyers, smaller cities would not be able to access utility-scale projects on their own, making it difficult to reduce their carbon emissions efficiently.
Creating Knowledge-Sharing Opportunities
By joining together, cities can not only aggregate their buying power but also pool their knowledge to streamline procurement processes. The shared experience among participants can generate positive network effects, including increased mentorship, increased credibility, and support for inexperienced buyers.
For example, the City of Nashville partnered with Vanderbilt University last year to purchase electricity from a 125 MW solar project as part of the Tennessee Valley Authority’s Green Invest program. This public-private partnership allowed the city to leverage the expertise of the University’s Large-Scale Renewable Energy Study Advisory Committee to identify the best risk mitigation strategy.
According to Susan R. Wente, interim chancellor of Vanderbilt University, “We want this partnership to serve as a model of collaboration that other organizations within our region and beyond can replicate to make long-term, lasting changes to protect our shared environment.” In fact, the connections formed within the aggregation group have garnered national media attention and are sending a powerful signal to utilities, policymakers, and developers that local governments are serious about rapidly decarbonizing the electricity system.
In addition, a group of buyers can also share external lawyers, accountants, or consultants. For instance, 15 Pennsylvania municipalities and public entities, which also participated in the Renewables Accelerator’s Large-Scale Renewables Aggregation Cohort, have teamed up to investigate the viability of investing in a joint solar deal. The 15 entities issued a joint RFP for energy consultants in May 2021 to share external advisory services.
Unlocking More Cost Savings
Throughout the collaborative process, aggregated deals can produce various cost savings because they enable cities to achieve greater economies of scale by combining the renewable energy demands of multiple buyers.
For example, a National Renewable Energy Laboratory analysis estimates that procuring 100 MW of solar instead of 5 MW can reduce development costs by 24 percent. This can lead to cost savings in the form of lower power purchase agreement prices for all buyers, regardless of size.
In another case, the company Enel X, which is working with the BRCPC on a joint purchasing strategy, found that renewable energy projects typically must be over 20 MW in size to be economical. The company discovered that aggregation is one way for smaller buyers to participate in large projects.
In Florida, 12 cities joined together to form the Florida Municipal Solar Project. They are developing 372.5 MW of zero-emissions energy capacity, enough to power 75,000 Florida homes. According to Jacob Williams, CEO and general manager of the Florida Municipal Power Agency, “By working together, our cities are able to provide clean power to their communities in a cost-effective way.” Clint Bullock, Orlando Utilities Commission general manager and CEO, explained, “We can leverage the economies of scale to bring the price of solar down to a point where a dozen municipal utilities can afford to sign on and I believe this is something people around the country will take notice of.”
Better Together
As more cities set goals to transition to renewables, aggregation is democratizing clean energy access by enabling participants, especially smaller buyers, to collectively develop significantly larger renewables projects than any one buyer would be able to access individually. The partnerships can create positive network effects through knowledge sharing and inspire other organizations within the region to replicate the collaboration model. By unlocking more cost savings, aggregated deals provide a lower-cost mechanism for cities to achieve climate goals efficiently.
The new IPCC report underscores the urgency of decarbonizing the electricity system and reducing GHGs. To play their part, cities need to increase the pace and scale of renewable energy procurement. Although aggregation is still a relatively underutilized procurement method, this approach is crucial to help them do that.
Procuring Large-Scale Renewables through Aggregation: A Guide for Local Governments helps walk local governments through the aggregated procurement process step-by-step and links to other key tools and resources relevant to each stage.
Cities must act now to curb greenhouse gas emissions. The best path forward involves engaging all actors and ensuring a more promising economic structure for a wide array of purchasers. In the battle against climate change, it is better to aggregate than to go it alone.
Article courtesy of RMI.
It’s finally happening. After years of promises, missed timelines dating back to the “Autonomy Day” in 2019, and endless iterations of “Full Self-Driving” (FSD), a Tesla vehicle has been spotted driving on public roads in Austin without anyone in the driver’s seat or a safety monitor in the passenger seat.
Elon Musk has confirmed that Robotaxi testing has officially commenced. This is undeniably a step forward for the company’s autonomy ambitions.
But it is also a terrifying leap of faith, given the complete lack of safety data proving the system is ready for this.
The sighting, captured over the weekend by locals in Austin, shows what appears to be a specially outfitted Model Y, presumably a testbed for the upcoming dedicated Robotaxi platform, navigating city streets. The steering wheel is turning, the car is moving, and the driver’s seat and front passenger seat are empty:
Following the online buzz surrounding the sighting, Elon Musk took to X to confirm the obvious:
“Testing is underway with no occupant in the car.”
In isolation, this is exciting news. It suggests Tesla has reached an internal confidence level in their latest FSD builds for Robotaxi (not in consumer vehicles) where they feel comfortable pulling the human monitor.
It’s the tangible progress toward the driverless future many Tesla owners bought into years ago.
However, there’s still a lot of room for concerns.
Tesla has, to date, never released comprehensive, verifiable data proving that its FSD system is safer than a human driver. We get anecdotal evidence, curated video clips, and high-level statistics about “miles driven,” but not the granular disengagement data that competitors like Waymo provide to regulators and the public.
In fact, the data we do have, based on incident reports submitted to the NHTSA under their Standing General Order regarding ADS and ADAS systems, paints a worrying picture.
The data pointed to Tesla’s Robotaxi pilot in Austin having a crash every ~62,000 miles, significantly higher than the human average, despite a safety monitor inside the car that should have prevented further crashes.
CEO Elon Musk said last week that he expects Tesla’s Robotaxi service in Austin will be without a safety monitor within three weeks.
Electrek’s Take
Think about that for a second. The current fleet requires human intervention to avoid crashes. We know this. If human interventions are currently preventing accidents, common sense dictates that removing the human without a massive, documented improvement in the system’s base capability will lead to more incidents.
Tesla seems to be skipping the “prove it’s safe” phase and jumping straight to the “deploy it” phase.
I want Tesla to succeed here. A functional, scalable Robotaxi network would be a civilization-level improvement in transport. Seeing a driverless Tesla on public roads might feel like a visceral milestone, proof that the technology is advancing.
But “advancing” is not the same as “safe.”
I have serious concerns about the fact that Tesla has consistently avoided releasing verifiable, valuable data on the safety of FSD or its Robotaxi pilot program.
We have to try ourselves to match Tesla’s sparse release of Robotaxi mileage to the limited crash data reported to NHTSA. And that doesn’t look very good for Tesla.
So far, and even with this sighting, the Robotaxi program in Austin seems more of a marketing effort than the true first step toward scaling a driverless ride-hailing service. It looks like an effort to manufacture a win while Waymo rapidly scales its commercial driverless system.
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The Cat 793 XE Early Learner battery-electric haul trucks deliver all the performance of its diesel-powered siblings without the noise, vibrations, and harmful emissions – and now, they’re being put to the test at BHP’s iron ore mine in Australia.
Part of a collaborative effort between BHP and Rio Tinto to help decarbonize BHP’s Jimblebar iron ore mine in the Pilbara, these 240-ton Cat 793 XE Early Learner electric haul trucks represent a major step toward a more sustainable future in mining, designed to deliver zero exhaust emissions while maintaining productivity and performance.
“Powering up our first battery-electric haul trucks in the Pilbara is an important step forward on the mining industry’s road to decarbonization,” says BHP Western Australia Iron Ore Asset president, Tim Day. “Replacing diesel isn’t just about changing energy sources, it’s about reimagining how we operate and creating the technologies, infrastructure, and supply chains to transform mining operations. These trials will help us understand how all the pieces of the puzzle fit together: the battery technologies, generation and charging infrastructure, power management, as well as the supply chains to potentially deliver this at scale.”
Like the two trucks deployed at Newmont’s Cripple Creek and Victor mine in Teller County, CO last year, this phase of Caterpillar’s Early Learner program will see the company attempt to integrate multiple electrified trucks at a single site with remote operators, validating the integration of a battery electric fleet with CAT’s existing autonomous and fleet management systems.
Decarbonisation of Pilbara iron ore operations will rely on technology advancements and breakthroughs in research and development, which is why BHP and Rio Tinto are working closely with Caterpillar to accelerate their fleets’ transition to electric power.
That, and the fact that they’re watching global mining giants Fortescue slash hundreds of millions of dollars from their operating costs by switching to electric, and (presumably) want to get in on that action sooner than later.
Despite the urgency, however, they need to get it right or risk huge disruptions that will eat up any projected efficiency gains. “A significant shift like this demands a strong commitment to research and development, coupled with collaboration across the industry,” adds Day. “This is going to take time to get right, which is why trials like this one with Rio Tinto and Caterpillar are so critical.”
Caterpillar 793 XE Early Learner
The big Caterpillar haul truck is powered by a 564 kWh lithium iron phosphate (LFP) battery pack that sends electrons to a 480 kW (645 hp) electric motor that kicks out an undisclosed amount of torque – but which is more than capable of hauling 250 tons of truck and payload at the same 38 mph to speed as its 2,650 hp diesel-powered bretheren.
The best part: in the right conditions, a heavily-loaded haul truck can rely on regenerative braking to keep it topped off, enabling ’round-the-clock operation without the need to stop and charge – a trick diesel trucks absolutely cannot match.
SOURCE | IMAGES: Caterpillar, via Heavy Equipment Guide.
If you’re considering going solar, it’s always a good idea to get quotes from a few installers. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. It has hundreds of pre-vetted solar installers competing for your business, ensuring you get high-quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use, and you won’t get sales calls until you select an installer and share your phone number with them.
Your personalized solar quotes are easy to compare online and you’ll get access to unbiased Energy Advisors to help you every step of the way. Get started here.
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A few weeks ago, we talked about some real-world numbers shared by Redditors who added a rooftop solar system to their homes. Not to be outdone, Electrek readers took to the comments to share their own real-world solar numbers. Here are some of the best!
That original post, which you can read here, was inspired by a Reddit user going by DontBuyBitcoin who shared a screenshot on r/Solar indicating that their newly-installed ~11.5 kW system produced over 1,700 kWh of electricity in October. “Pretty surprised by the production of the system I got,” writes DontBuyBitcoin. “11.48KW. I cant wait to see what JUNE-AUGUST [2026] going to look like 😍 I wish SolarEdge will make their app better looking with more functionality.”
Other Redditors were quick to share in the enthusiasm, but our Electrek readers weren’t going to be outdone, and shared their own results in the comments section.
I’ve got a 49 panel, 16.5 kW system just outside Austin, TX, and while it’s expensive ($320/mo), I produce much more power than I use each month. But with 2 EVs, a hot tub, and air conditioning in a Texas summer, I’m not mad I have all this. On a current sunny day, I’m producing about 65 kWh. I top out around 107 kWh on a long but somehow not hot day.l in late spring or early fall (whatever that means in Texas).
Another reader, Craig Morrow, had a much smaller system at “just” 6.5 kW compared to David’s 16.5 kW deal, but still put up some highly respectable numbers.
My 6.5 kw PV generates from 16 kwh/day (winter) to 38 kwh/day (late spring). Between the efficiency of my house and my consumption habits, my usage averages 5-6 kwh per day. Went all-in on passive and active solar when I built the house ten years ago, an investment which has long since paid for itself with no heating or utility bills, plus having battery storage means no worries about power outages when the grid goes down. A great feeling to be energy independent!
Craig had the top comment with twenty upvotes, but he wasn’t the only reader to see some big efficiency gains with home solar. Several of you posted about the cost of your system, and when you’d begin to see an ROI with the savings you were seeing.
My ROI on a $42k system ($30k with the IRA tax credit) was calculated to be 15 years assuming a 4% yearly rate increase. Without the tax credit it would likely be 20+ years. It makes no sense financially. Interestingly, Europeans pay a lot less for similar size systems. Why is that?
Another commenter, Leonard Bates, was also seeing great returns – but took things a step further by doing some extra math to compare the cost of fueling up his car with gas vs. topping it off with electrons generated by his home solar system.
It is hard for the average Joe to understand electricity production numbers, so I have reduced our experience into dollars. We have a 8.8 kWh rooftop system and two EVs that (other than a few vacation trips a year) are charged at home. We are retired, so we can charge during the day. Bottom line, we saved over $4,000 by not buying gasoline last year (drove ~41,000 miles). Electric bills, with the load of the EVs, is basically a breakeven. The system cost us about $22,000, so a breakeven on the system of about six years and then free electricity for another 20, until the panels need to be replace. Plus we are “energy independent” for our cars. If there is turmoil in the Middle East, it doesn’t affect our pocket books.
Leonard’s math reminds me of landscaper Colin Ash, who has been operating Ash Landscaping for over 30 years and recently traded his diesel excavator in for an electric JCB mini excavator he powers exclusively with solar panels mounted on his carport. “I’m a long-time electric vehicle driver and run my cars on solar energy generated from solar panels on the roof of the car port at my home,” explains Ash. “Adding the new JCB 8008E CTS was a perfect next step and I can plug it in next to the car and charge both overnight.”
So, Ash is happy. It seems like you guys are pretty happy, too – even without the home solar tax credit that a lot of you didn’t even know existed in the first place. Here’s hoping a lot more people decide to share their results with home solar, too.
Or, as one of our commenters put it:
If more homeowners share data like this, it’ll help others make informed decisions rather than relying just on sales projections.
Original content from Electrek.
If you’re considering going solar, it’s always a good idea to get quotes from a few installers. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. It has hundreds of pre-vetted solar installers competing for your business, ensuring you get high-quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use, and you won’t get sales calls until you select an installer and share your phone number with them.
Your personalized solar quotes are easy to compare online and you’ll get access to unbiased Energy Advisors to help you every step of the way. Get started here.
FTC: We use income earning auto affiliate links. More.
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