Speaking at the 2014 Michelin Challenge Bibendum in Chengdu, China this week, Cooley explained how ITM's electrolyzer system, when connected to the electric grid and the local natural gas pipeline, can basically get you zero-cost hydrogen fuel for your fuel cell vehicle. It's not a completely new idea, but here's how it works.
Cooley started by noting that the UK has tremendous wind power potential, especially in the north, in Ireland and Scotland. Cooley said it was, "the richest wind resource in Europe, which would be fantastic if we could harness it properly." That's a catch, though: the grid doesn't have enough storage capacity to hold on to a lot of renewable energy if it happens to be generated when you don't need it. If it's windy when people are sleeping, for example, the energy is likely to be wasted. Some utilities have plans to use giant battery banks, especially those that have served time in plug-in vehicles, to store this electricity, but ITM thinks its hydrogen electrolyzers are a better solution for the massive amounts of power that a city or national grid needs. "There's a threshold that you get to, which is about 20 percent by capacity by renewable power," Cooley said, after which "you start to turn down considerable amounts of that power." The UK hit that threshold last year, he said, which had a big cost: "We turned down one terrawatt-hour of renewable power." Ouch.
In 2013, the UK turned down one terrawatt-hour of renewable power.
The reason for it is a little complicated, but stay with us. Let's say that you're a utility and your total grid capacity includes 20 percent wind power. One day, everyone is using all of your electricity, and then all of a sudden, the wind starts raging and you'd like to send your customers that emissions-free power instead of burning your fossil fuels. To do that, you have two options: you can quickly reduce your fossil fuel power generation by 20 percent, or you can find a way to store that wind energy for the future. Slowing down and then restarting giant coal- or oil-fired generators can take 12 or 6 hours, respectively – and shutting down a nuclear plant can take up to 48 hours – so those aren't reasonable options. Thus, storing or using all that temperamental wind energy becomes the better choice, at least over the short term.
That makes storing or using that temperamental wind energy the better choice.
As stated, you could save the energy for later use in big battery packs, but Cooley and ITM Power say that their hydrogen electrolyzers offer a far superior solution because of something called grid balancing, which is the obligation by the transmission operator to achieve 50 Hz on average every hour. Grid balancing "is about frequency and it's about balancing the supply side with the demand side," Cooley said. Different countries require different outputs (in the US, it is 60 Hz; in China and the UK, 50 Hz), so the following numbers aren't applicable everywhere, but we'll let Cooley explain it from here and you'll get the gist (Wikipedia can also explain it):
If demand goes up, then frequency falls and all of the machines slow down. So, your basic option as a utility is to either turn generators or loads on or off. People in the plug-in vehicle space find this familiar because utilities talk about not sending power to your EV when other load demand is strong, making sure to charge your car when overall load demand is weak. ITM's solution is to use the extra wind energy (or whatever) to turn on electrolyzers. When compared to the time it takes to turn on the fossil fuel power generators mentioned earlier (or even the fastest fossil fuel option, gas turbines, which take two minutes), electrolyzers can turn on or off in 1/5th of a second. Using electrolyzers with that sort of response time, "gives you the very lowest-cost hydrogen," Cooley said. "In fact, you can more than halve your electricity price by providing grid balancing to get very low-cost hydrogen."
50 Hz means all the machines are synchronized to rotate at 3,000 rpm. ... If you take a machine like that and you overload it, it will slow down. If you underload it, it will speed up. And that's the frequency. If you get to half a hertz below 50 Hz you have to start an arrestive action, and if you get to between 48 and 52 hertz, you log the power station off the system.
Being able to switch the electrolyzer on or off quickly is only part of the challenge. The real benefits come when you can also store all that power. Battery banks can accept big energy dumps in a short time, but Cooley said that their main problem is cost. It's pricey to go from storing a kWh to a MWh to a GWh. An electrolyzer, on the other hand, can turn water into hydrogen whenever the grid says it's a good time to do so and then store the hydrogen in the natural gas network. "Small amounts of renewable power, via electrolysis, are put into the gas grid as hydrogen and you decarbonize the gas grid," giving you the ability for "massive" storage, Cooley said.
"You can more than halve your electricity price by providing grid balancing to get very low-cost hydrogen." – Graham Cooley
If you're just storing a few seconds of excess electricity, then a flywheel is the most efficient way to do that. If you're going to store up to two or maybe four hours worth, then batteries make sense, and every time you want to add another hour of capacity, you need to buy another battery. But, with hydrogen, "you store the energy in the gas grid, not the electric grid." In Europe today, you can put up to three or five percent of hydrogen into the gas grid. In the UK, in fact, the natural gas grid used to be 60 percent hydrogen. "That's terrawatt-hours of energy storage," he said.
Getting the H2 back out of the natural gas pipeline is also not that difficult, it seems. A PDF from the DOE called Blending Hydrogen into Natural Gas Pipeline Networks: A Review of Key Issues has this to say:
So, that's the theory, anyway, and ITM Power is taking things beyond theory. It has a pilot electrolyzer project in Frankfurt, Germany and will build three hydrogen refueling stations in London at a cost of 2.8 million pounds ($4.4 million). It also has two refueling projects in the works in California and, overall, has 9.56 million pounds ($14.9 million) of projects "under contract or in the final stages of negotiation" around the world. So, if this system is really the best, we should be able to see some real-world results in the near future.
Blending hydrogen into natural gas pipeline networks has also been proposed as a means of delivering pure hydrogen to markets, using separation and purification technologies downstream to extract hydrogen from the natural gas blend close to the point of end use. As a hydrogen delivery method, blending can defray the cost of building dedicated hydrogen pipelines or other costly delivery infrastructure during the early market development phase. This hydrogen delivery strategy also incurs additional costs, associated with blending and extraction, as well as modifications to existing pipeline integrity management systems, and these must be weighed against alternative means of bringing more sustainable and low-carbon energy to consumers.