Welcome to the June 2016 edition of the Direct Energy Buzz! This month, we will discuss carbon capture technology that rapidly converts carbon dioxide (CO2) into limestone, how a 19th century railroad idea can store electricity, and how well the stack effect powers high-rise urban living.
Turn to Stone
The annual Carbon Capture, Utilization, and Storage (CCUS) Conference fired up in Tyson’s Corner, VA in June 2016. The conference brought together experts and industry representatives to examine best practices to remove CO2 gasses from fossil fuel burning and put those into the ground. Current projects rely on pumping gas deep underground, into either salt mines or depleted oil wells thousands of feet deep. Carbon sequestration’s success has been largely illusive due to high cost and the problem of CO2 leaking out of the subterranean storage and making its way back to the surface.
The CarbFix Project in Iceland has found way to bind CO2 to volcanic basalt rock formations in geothermal fields. The idea is to produce limestone through the natural chemical reaction of the basalt’s calcium, magnesium, and iron with CO2 from the air.
The process requires drilling down over one thousand feet into a layer of volcanic basalt and pumping in LOTS of water to combine with CO2 in the bore hole (in this case, pumped in from the Hellisheidi geothermal power plant outside Reykjavik) to create a slightly acidic carbonated water. The water then enters the basalt layer and the chemical reaction begins.
The study has found “that >95% of the injected CO2 was mineralized through water-CO2-basalt reactions between the injection (HN02) and monitoring (HN04) wells within 2 years.” Core samples in the experimental area reveal basalt rock with new white carbonized deposits of limestone. As for CO2 leakage, the researchers used radioactive Carbon 14 as a marker in the gas mix. They detected none — indicating virtually all the CO2 had been bound to the deep basalt rock.
The technology is still young. Of the volume amounts pumped into the basalt layer, only 5% was CO2 (which possibly could be recovered in time). The main cost, however, comes from CO2 capturing at the source — places like electric generators, cement plants, and steel mills. Thankfully, basalt is practically everywhere — especially on the floor of the Atlantic Ocean – as it makes up roughly 10% of the earth’s geology.
Return of the Gravity Railroad — as Energy Storage?
Growing up in Reading, PA, in the shadow of Mt. Penn and stories of its once-grand 19th century hotels, I learned in school about its gravity railroad. Passengers would board cars at the base of the mountain and these would be pulled by a steam-powered geared locomotive to the summit at a hotel. The downhill trip had no locomotive, the cars rolled down the side of the mountain relying on expert brakemen and very good braking systems.
Almost a century later, the tracks are gone, but the roadbed still exists. In fact, there’s quite a lot of abandoned rail line in that part of Pennsylvania and elsewhere ‘round the country.
So, I was tickled to stumble onto Advanced Rail Energy Storage (ARES), which has just received the green-light from the Nevada Bureau of Land Management to begin building its own energy-storage gravity railroad. The idea is to use automated electric locomotives to push a heavy rock-loaded train up a hill using excess off-peak energy. During peak usage, the brakes are released and the train rolls down hill —but uses their electric motors as generators.
The system is expected to work at 80% efficiency and is scaleable. The entire complex using upper and lower rail yards can store from 100 megawatts to 3 gigawatts. Compared to other stored energy systems such as enormous hydro-storage facilities, this would be far cheaper to build and potentially could be located on abandoned railwats near densely populated areas.
How Does This Stack Up?
In the winter, the stack effect in our homes means that warm air flows out through the attic of our homes and pulls in the cooler air from outdoors. It wastes energy, raises your heating costs, and is something you want to avoid.
Unless you strap a tube to the side of silo with a wind turbine on top. Then you can use it to make electricity.
That’s what GRNE Solutions plans to do with an old grain silo in Minneapolis. The tube will be 7 1/2 feet in diameter and use the stack effect to pull up enough air flow to crank a 3 kW wind turbine. The tube, called the Energy Column, requires buildings to be at least 10 stories ( 100 feet) tall. While the Energy Column isn’t applicable for a suburban home, it has already proven effective for urban high-rises.
The real estate development company that own the silo (and several others) wants to turn them into productive assets.