power of cool: liquid air to store clean energy - commercial energy storage systems
Created by Helen nitty Coren;
"Standing in a container filled with pipes and valves, wearing a helmet and strong boots, the renewable energy mix takes a box of sunshine and we stare at a gray panel, the switch is green and red.
"This panel means we are connected to the grid," my companion Rob Morgan said with a proud smile . ".
"It's really exciting for engineers.
"We are in an industrial zone in SLO, UK on the grounds of 100
Energy companies in Scotland and south have megawatts of biomass power plants.
But what we see is a small group of containers and a sparkling white liquid nitrogen tank hidden in a corner of the site.
Here, Morgan, chief engineer of high view Power Storage in London, and his colleagues have been running a pilot plant designed to store potential energy in the form of liquid air.
Until recently, the only way for grid operators to store energy was in large hydropower reservoirs.
In the future, renewable intermittent generators will make up a large part of our energy portfolio.
So we need a way to store the electricity they produce in order to use it for hours or even days when the sun does not shine or the wind does not blow.
Since we cannot build a huge new reservoir near every big city, a more compact storage system is the key to green power in the future.
That's why Highview has been testing its 300-
Over the past nine months, it has provided power to the British state grid.
The process stores excess energy when demand is low by cooling the air around190 °C.
Excess power powers the refrigerator that cools the air, and the liquid air or refrigerant that is subsequently generated is stored in the storage tank at ambient pressure (1 bar).
When electricity is required, the refrigerant is subjected to a pressure of 70 bar and heated in the heat exchanger.
This creates a high
Pressure gas driving turbine power generation.
Cold air generated from the turbine is captured and reused to produce more refrigerant.
Highview's chief executive, Gareth Brett, said the process, which uses environmental heat to heat it, recycled about half of its electricity.
If you use the residual heat of a nearby industrial or power plant to heat the refrigerant to a level above the ambient temperature, the efficiency will increase to around 70, which increases the force of the turbine, he said. Unlike pumped-
Storage of water and electricity requires a large reservoir, and the refrigerant plant can be located anywhere, Brett said.
The efficiency of the batteries being developed in Japan is about 80-90, but the cost is about $1;
4000 power generation per kWh.
Low temperature storage costs only one dollar;
Brett claims to be 1000 per kilowatt because it requires less expensive material.
"Lower costs are always better for energy storage, even if it comes at the expense of slightly less efficiency," said Aidan Rhodes of London's UK Energy Research Center . ".
So far, the high view has been receiving the refrigerant from an external source and using it to store and produce power.
But the company recently added one.
On-site liquefaction plant and will start producing its own refrigerant from later on.
It plans to build a 3. 5-
Commercial MW
By the end of 2012, the scale system will be increased to 8 to 10 MW plants by the beginning of 2014.