Tuesday, March 15, 2016
Man the Batteries!
As most my readers know, I have a particular interest in power generation in an era of accelerating global climate change. You are also aware that one of the weakest links in the world of alternative power generation is inconsistency. No wind, then wind power stop making electricity. No sun, no solar-generated electricity. The answer, of course, is the ability to store energy for use when the active power is in one of its down moments.
Many simply transfer the electrical energy produced into some other form to be used later. For example, electrical power can be used to create mechanical energy that is unleashed later. Some solar farms, in addition to making electricity currently available, also heat massive stores of salt, which can be used when the sun is down to generate the power necessary to turn the turbines of adjacent generators. As illustrated below, this use of heated salt has evolved to a new level that could change the dynamics of environmentally-friendly electricity.
The most useful energy storage, at least at the consumer level, comes in the form of smaller batteries. We aren’t exactly going to see a Tesla with a giant salt pack, and for consumers generating electricity at the homes or businesses, the most likely technology is still the battery. Recent blogs have spokes about new generations of such systems that are moving away from expensive rare earth batteries, like the new aluminum batteries being developed.
But the ability to service the largest traditional fossil-fuel-burning power plants, to create massive energy storage capacity, is the big ticket to reducing greenhouse gasses. GE has actually figured out how to use one of the “big nasty” components in greenhouse gasses – carbon dioxide (CO2) – to store electricity.
This is particularly significant in the “solution” to so-called “clean coal.” There is no currently-available, commercially viable system to eliminate the CO2 from coal-fired electrical power plants. So what happens to those emissions? To the extent they are not simply released into the atmosphere, such pollutants are simply shoved underground, stored to be dealt with by future generations. So much for “clean coal.” So if somehow this mass of stored CO2 could be used in an environmentally-positive manner, this would be a big step towards the containment of greenhouse gasses.
“GE says it’s figured out a way to put that stored CO2 to use by using it as a giant battery that could store excess solar energy. The technique would also resolve another long-standing energy problem: how to store solar energy so you can use it when needed most—at nights or on cloudy days. ‘That’s the grand challenge,’ according to Stephen Sanborn, senior engineer at GE Global Research. ‘We need to make renewable energy available to the grid when it is needed.’
“Sanborn’s solution works in two parts. The first collects solar energy and stores it in a liquid of molten salt. The second part uses surplus electricity from the power grid to cool liquid CO2 so it becomes dry ice. During power generation, the molten salt transforms the dry ice CO2 into a ‘supercritical’ fluid, that is a state of matter that neither has specific liquid nor gas phases. That supercritical fluid then flows into a CO2 turbine called the sunrotor [pictured above]. It is the sunrotor that can then dole out the stored solar energy as needed. Sanborn’s team has created a version of the sunrotor that is small enough to fit on an office shelf, yet power 100,000 homes.
“Sanborn says the sunrotor could bring the cost of energy down from $250 per megawatt-hour to $100 per megawatt-hour. ‘It is so cheap because you are not making the energy, you are taking the energy from the sun or the turbine exhaust, storing it and transferring it,’ he says. Once deployed sunrotors could yield as much as 68% of stored energy back to the power grid. Even the most efficient gas power plants currently only yield 61% of energy back to the grid. As for the timeline of deployment, Sanborn says sunrotors could see widespread use within 5 to 10 years.
“‘The result is a high-efficiency, high-performance renewable energy system that will reduce the use of fossil fuels for power generation,’ Sanborn says.” FastCompany.com, March 9th. We’re getting there, slowly, but weather-related disasters are only accelerating. Time is not on our side, but I thought a little good news would be welcomed just about now.
I’m Peter Dekom, and climate change requires individual efforts coupled with the biggest technology solutions we can find.