Forget the smart grid – think nitrogen grid
By Toronto Star
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Albertan oil veteran Dave McConnell is pumping the "nitrogen grid" these days, and he figures that within 15 years his new system could do away with the need for high-voltage transmission lines and offer a way to store energy from wind farms.
You may recall McConnell's Edmonton-area company, Lancaster Wind Systems, which I wrote about 18 months ago. It had just received a grant from Sustainable Development Technology Canada to demonstrate a hydraulic system that can store wind energy in high-pressure pipelines.
The company was keeping tight-lipped at the time, but during a recent visit to Edmonton the Toronto Star got a chance to chat with McConnell about his invention and how it might change the way we think about power generation and energy storage.
"It's a whole new technology – cutting edge and out of the box," says McConnell, 65, a hydraulics engineer who has spent most of his working life on offshore oil rigs.
In 1997 his wife told him to get out of the oil business, so McConnell began applying his knowledge of hydraulics to other areas, including designing and building hydraulic drive systems for vehicles. It wasn't until 2003, however, that McConnell turned his attention to large-scale energy storage.
The problem with today's electricity system is that, for the most part, power must be consumed when it's generated. In other words, supply and demand must be carefully balanced. Every electron that's produced and put onto the transmission system, whether from uranium, coal or wind, must be used somewhere along the grid or else the whole system can crash.
This gets tricky when dealing with the wind, which doesn't necessarily blow when we need it. Large-scale energy storage can solve this problem by absorbing supply when it's not needed and releasing it when we do. But batteries are too expensive today, and other options – such as compressed-air storage in salt caverns – are largely limited by geography.
It's here where McConnell's oil and gas experience fuelled his imagination. He knew that North America had an oil and gas pipeline network stretching thousands of kilometres, and that these pipelines – some of them not in use – were capable of holding highly compressed gases.
What if, initially, unused portions of this pipeline network could be used to hold compressed nitrogen, an inert gas that represents more than three-quarters of the air we breathe? And instead of capturing wind energy and converting it into electricity for the grid, what if we could build special wind turbines that convert the wind into hydraulic energy that's used to compress nitrogen and inject it into a common pipeline?
The idea is that the pipeline would become a big battery consisting of compressed nitrogen – that is, a nitrogen grid. At various points along the pipeline where electricity is needed, special generators would tap into the compressed gas and produce electricity as the nitrogen is released and rapidly expands.
"It's a closed-loop system," explains McConnell, referring to the fact that the nitrogen is always recycled back into the pipeline. "We're reusing, reusing, reusing."
Presumably it would take a lot of energy initially to charge the pipeline with nitrogen and to reach the desired pressures – for example, 1,440 pounds per square inch for a 32-inch pipe. The initial nitrogen also has to be produced. But once that has been achieved, maintaining desired pressures and periodically replenishing any lost nitrogen would be a fairly simple operation.
The underground pipeline, in essence, would eliminate the need for high-voltage transmission, and a new generation of wind turbines across North America could theoretically feed the nitrogen grid.
While McConnell is careful about releasing too much information, he has raised several million dollars and has several dozen investors, including a few oil and pipeline companies and some well-known venture capital firms that – for the time being – will remain nameless.
Their engineers have gone through the plan with a fine-toothed comb, says McConnell, who is certain it will all work as envisioned. Silicon Valley venture capitalist Vinod Khosla has been talking with Lancaster Wind, but the extent of his involvement is unclear.
I should point out that existing wind turbines can and will be used to compress the nitrogen gas using electrical energy. This is a less efficient approach, but it at least lets Lancaster demonstrate the energy storage system during first-phase deployment.
McConnell is thinking he can eventually do away with wind turbines altogether, and instead deploy small nuclear reactors –just a few megawatts in size – along the pipeline to do the compression and nitrogen production.
Any energy source can theoretically do the hydraulic conversion. Whether the best option is nuclear, wind or some other form of generation is open to debate.
The basic concept, however, is likely to attract more attention over the coming months as word of this unique technology spreads.
