SunTrain Re-Imagines Battery Storage & Clean Energy

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Thermal generating stations keep producing electricity as long as there is fuel to boil water to make steam to spin turbines. They don’t care what the weather is outside. As long as there’s steam, there’s electricity. Over the past 100 years or so, most humans have gotten used to having all the electricity they need available at all times of the day or night. If you need to use your welder at 3:00 am, there’s juice enough to make that happen. Our refrigerators and water heaters and air conditioners need to work at night as well as during the day. As the failed president of the United States loves to point out, the sun doesn’t always shine and the wind doesn’t always blow. New transmission lines could send electricity to where it is needed, but they are expensive and take years to plan, permit, and build. SunTrain thinks it has a better idea. On its website, the company says:

“Electric transmission of renewable energy can be the least cost solution to enable emission reductions when it is not burdened by the challenges to construct transmission lines which may include permitting, acquisition of land, working around existing infrastructure, and stakeholder opposition. Rail infrastructure is an existing asset which has historically supported coal generators and now presents an alternative mechanism to deliver clean energy at low cost. SunTrain brings an innovative project development solution that moves grid-ready electricity via utility-scale battery energy storage fixed to rail cars.

“SunTrain resolves massive transmission bottlenecks that are throttling renewable energy development and generation. SunTrain seamlessly stores green energy from remote solar and wind farms within customized battery containers that are transported over existing railroad networks. This links generation sites and congested substation nodes, bypassing the conventional transmission system. SunTrain solves the problems of decades long transmission bottlenecks through a new means of green energy distribution — ‘Trainsmission®.’”

Now, we know some readers are going to get the heebie jeebies thinking about diesel locomotives hauling railroad cars loaded with fully charged storage batteries back and forth across America, but think about it — the tracks, locomotives, and freight cars are already in existence. Why not use them now instead of waiting for transmission lines to get built 10 or 15 years from now? By doing so, we give the lie to all the bozos who give us “the wind doesn’t always blow and the sun doesn’t always shine” song and dance. If SunTrain could provide enough battery power to support normal grid operations in a major city like Denver, Colorado, would that not be a good enough reason to do this?

SunTrain Pilot Project  In Denver

The energy grid in and around Denver is a microcosm of the US energy grid. Demand for electricity is rising to power data centers and electric vehicles, yet Colorado’s grid can’t keep up with the new amounts of renewable energy that are available, which means much of it goes to waste. The state will need to invest as much as $8.7 billion more in its grid by 2045 according to the Colorado Electricity Transmission Authority. While grid upgrades are underway, SunTrain technology could bridge the gap between the grid of  today and the grid of tomorrow. Once the new grid is completed, SunTrain could move to other locations where energy storage is needed.

According to Anthropocene Magazine, 20 car battery trains envisioned for SunTrain’s Colorado pilot would shuttle between a pair of power plants. Most likely, they would fill up with surplus energy from Xcel Energy’s solar power facilities near Pueblo, then travel 150 miles on the Union Pacific Railroad to Denver where the trains would release their stored energy at a power plant in the city center.

One challenge for SunTrain is automating the train-to-grid connection. SunTrain currently plugs charging cables into its battery storage rail cars by hand. The company is designing an automated system that uses robotic arms trackside to plug into each battery car using charging technology developed for electric buses, trucks, and ferries by Swiss engineering firm Stäubli.

One task the company hopes it has already checked off is addressing worries about safety. It says it exclusively uses LFP batteries because they are far less prone to catching fire than NMC batteries. Co-founder Jeff Anderson says a recent 12 day transit from San Francisco helped reassure railroads that its rolling batteries are safe. “We proved that you can actually move power from one place to another and the batteries don’t shake to death. They don’t explode. Everyone’s still alive,” he says. LFP batteries are heavier, but as Anderson notes, “Railroads are really good at moving heavy things.”

Diesel locomotives do add a carbon penalty to the equation of about 25 grams of carbon for every kilowatt-hour of power delivered. While not ideal, that’s still 17.5 times cleaner than power from a methane-fired thermal generating plant. SunTrain says it will need about $15 million to build its first train — a challenge today as the federal government slams the door on all spending not related to fossil fuels and national defense.

Another Idea For America’s Rail Corridors

Utilities and independent transmission developers in New York and New England have completed small sections of power lines next to rail lines, with bigger projects in the works. “There’s potentially a drastic reduction in the need for clearing rights of way. To me that’s a huge win,” said Jacob Lucas, director of transmission system planning at Eversource in New England. Co-locating power and rail is the right thing to do, he says, because doubling up the infrastructure protects natural spaces and communities from unnecessary disturbance. Sharing railroads’ existing rights-of-way also avoids the burden of securing permissions from a multitude of landowners and government agencies.

Lucas was involved in two recent projects that tapped rail corridors. One in Connecticut used several kilometers of Amtrak’s high-speed rail corridor near Hartford. Another, part of a joint venture with Danish offshore wind farm developer Ørsted, briefly hopped into the right-of-way for a Long Island commuter train to hook up New York’s South Fork offshore wind farm. That was the first large-scale project of its kind in North America.

Two bigger transmission projects in the works tap much longer stretches of rail property. The Champlain Hudson Power Express under construction to deliver Quebec hydropower to New York City follows tracks for over 200 kilometers. In the Midwest, the SOO Green line plans to follow rails for nearly all of its 560 kilometer journey from Iowa’s wind belt to Chicago.

Power transmission requires railroads to think differently about how they use their most valuable asset, which is land. Lucas thinks that’s why “co-location” success stories remain few and far between, and even those were hard won. “In most of the cases I’m familiar with, it’s taken a lot of effort.”

But these early projects show that the railroading business can make space for cleaner energy when project developers make it worth their while. If they ship fewer fossil fuels — particularly coal — in the future, they may embrace clean power to provide new sources of revenue.

The Takeaway

The SunTrain idea may not be as silly as it seems at first blush. After all, railroads have been transporting energy for a long, long time. This energy is just in a different form — electrons — instead of molecules. All in all, it seems more sensible than the train-to-nowhere idea in the middle of the desert in Nevada that would use excess renewable energy to move a heavily laden train up an incline and recover the energy on the way back down the hill via running the electric motors backwards. Think of it as regenerative braking in a Tesla Model Y that weighs a few million pounds.

The other thing that makes the SunTrain concept feasible is that BESS (battery energy storage systems) are often fitted inside standard 40 foot shipping containers and railroads have a lot of experience moving shipping containers. This is an idea that just might work, if sufficient funding can be found to get the first prototype train into service.