The world is at a turning point. We can either continue to add fossil-fuel infrastructure to the global energy system, or — and it’s an option that is becoming increasingly realistic due to huge technological advances in renewable energy — humanity embraces the low-carbon transition. These decisions will also have a huge impact on urban smog, pollution, and economic stability.
The stakes are high. But there is every reason to be positive. Renewable energy has been breaking records all over the world in recent years: renewables excluding large-scale hydroelectricity made up 53.6% of the gigawatt capacity of all technologies installed in 2015, exceeding the majority for the first time.
Making the switch to renewable energy requires a rethinking of the electricity network in terms of grid balancing and energy storage. For an insight into these challenges, cH2ange spoke to Dr Graham Cooley, CEO of ITM Power, a manufacturer of pioneering integrated hydrogen energy solutions to enhance the use of renewable energy.
In this two-part interview, Dr Cooley, discusses the role of hydrogen in the clean energy transition. In part 1 he talks about Power to Gas technology and grid balancing, while in part 2 he focuses on the benefits offered by renewably generated hydrogen for transport.
Yes I do, and there are a number of drivers. I don’t think we are going to carry on using the carbon molecule for energy. If the world switches to the electron or the hydrogen atom to carry its energy, then we can have a renewable and sustainable future.
“To move towards 100% renewables, we’ll need a significant amount of energy storage”
It’s pretty straightforward: to move towards 100% renewables, we’ll need a significant amount of energy storage because the sun doesn’t shine at night, and the wind doesn’t blow all the time. And that’s why hydrogen is absolutely fundamental to the future.
Many countries have experienced grid balancing issues as the proportion of renewable energy supplied to the electricity grid increases.
“We need long term, large-scale energy storage solutions”
It is difficult to match the unscheduled intermittent supply from renewables with demand.This is why we need long term, large-scale energy storage solutions, and this is why hydrogen is an indispensable part of the solution.
ITM Power specializes in what’s known as Power to Gas (P2G) technology, which involves making hydrogen using renewable power. A device called an electrolyser splits water into hydrogen and oxygen when an electric current is passed through. This hydrogen is used either in the gas grid or for refueling vehicles.
Because an electrolyser can be turned off and on very rapidly to provide very efficient grid balancing. Let me explain:
Electricity networks have a utility frequency of 50Hz in most countries, or 60Hz in others. This frequency is directly linked to turbine speed — 3,000 RPM for 50Hz or 3,600 RPM for 60Hz — which must be maintained to ensure the safe operation of the grid and the supplied appliances. When there is an increase in the power load, this is met by an increase in the power supply. However if there is not enough power, the turbines slow down resulting in falling frequency. The opposite happens if you under load the network, the turbines speed up causing rising frequency.
“The challenge with integrating renewable energy sources is their lack of inertia”
The obligation of the network operator is to compensate for such changes, by requesting more or less generation in the hour leading up to real-time, to keep the frequency just right. The challenge with integrating renewable energy sources is their lack of inertia, which has an impact on grid stability when using conventional methods for maintaining frequency.
This is the role of P2G. An electrolyser receives signals from the grid based on frequency. When the network is overloaded and the frequency starts to fall, the electrolyser is switched off. When the network is under-loaded, it receives a signal to turn on. Electrolysis equipment can be turned on and off in less than a second.
When switched on, the hydrogen produced goes straight into the gas grid. In this way, when we are balancing against rising frequency, an electrolyser can be used to absorb an excess of renewable power. The gas grid in the UK for example is three times the size of the power grid: there’s about 350 terawatt hours of energy flowing through the electricity grid every year, and about 1,000 terawatt hours in the gas grid. The primary difference between the two energy networks is that electricity has no energy storage, whereas there’s a huge amount of energy storage in the gas grid.
“If you want hours, days, months, years of energy storage, then you can’t do it with batteries”
So what you’re doing is using an asset that you already own — the gas grid — to store the energy from the electricity grid.
A lot of people immediately think of batteries when we talk about energy storage. And if you want one or two hours of energy storage, batteries are ideal. But if you want hours, days, months, years of energy storage, at massive volumes, and I mean terawatt hours of volume, then you can’t do it with batteries. But you can put hydrogen straight into the gas grid.
P2G was not invented by ITM Power or any of the electrolyzer manufacturers. It was a breakthrough that arose from the German power industry when it looked at ways to implement massive scale, long-term energy storage at low costs. And the costs are much, much lower than batteries. At ITM Power, we’ve reached a cost of one million euros per megawatt. Batteries are six times more expensive. And of course, as the scheme’s duration increases, the cost of hydrogen will go down further.
The limits for hydrogen concentration in the gas grid were worked out in a massive project by British Gas. In the UK, prior to 1969 we had 60% hydrogen in our gas grid. It was called town gas. When natural gas was discovered in the North Sea, an incredible project was undertaken in the UK to convert the whole gas grid from town gas to natural gas. For this reason, a lot of research into this subject has already been carried out and a 12% hydrogen concentration was established as the limit.
More recently, the Health and Safety Executive carried out a study on injecting hydrogen into the gas network and found that you can have a hydrogen concentration of up to 20% without affecting any of the existing infrastructure. In theory, you could have 100% hydrogen in the gas grid. But at concentrations of 12% and below, the gas has the same properties as pure natural gas, which means we can store all of our excess renewable power in the gas grid, without needing to change anything.
There’s not really any need. If the gas grid contains 1,000 terawatt hours of energy, 12% of that is 120 terawatt hours. At that level you can store one third of all the energy in the electricity grid in the gas grid — without exceeding the 12% and without needing to modify either the infrastructure or gas appliances.
In the UK, we have an important project called HyDeploy with National Grid and Northern Gas Networks. We are using a 0.5MW electrolyser to demonstrate the use of blended hydrogen in the UK gas grid. It’s a £6.8 million project which will establish a framework for hydrogen gas-grid injection in the UK and open up a new UK P2G market. It’s a three-year project, which we hope will play a significant role in the decarbonization of the UK gas grid.
Then there’s our RWE P2G installation in Ibbenbüren, North Rhine-Westphalia. Here we are implementing heat recovery from the unit, which increases the efficiency even more. For the first time ever, the electrolyser links together the supply of local electricity, natural gas and district heating, achieving a total system efficiency of 86%. Without heat recovery, our electrolysers have an efficiency of about 77%, which is still very high.
While in Germany we have the Thüga project, which back in 2013 became the first plant to inject electrolytically-generated hydrogen into the German gas distribution network. The Thüga plant is also a first in terms of primary grid balancing. The hydrogen made here is injected into the gas grid right in the middle of Frankfurt.
The European Commission’s package of measures, announced at the end of 2016, is the most significant proposal concerning P2G energy storage at the moment. The measures are designed to help the EU lead the way in the clean energy transition and to support the commitment of cutting CO2 emissions by at least 40% by 2030.
“Three very important measures are currently going through into law”
The package is changing the definition of energy storage to include hydrogen and P2G energy storage. Secondly, it is changing the rules of dispatch, so you have a level playing field between loads, energy stores and generation, and it obliges everyone to use curtailment [when wind and solar generation are shut down to balance the grid] only as a last resort. Turning on and off loads therefore becomes the priority. This is very important for the energy network. A final measure of the package is the introduction of a green certification scheme for hydrogen. These three very important measures are currently going through into law and will make a significant difference in the P2G industry once they are formally introduced.
In part 2 of this interview, Dr Graham Cooley discusses how hydrogen generated from electrolysers can also help bring about a revolution in sustainable transport.