The H2 Revolution

Marco Alvera is the former CEO of SNAM, an energy infrastructure company, now at Tree Energy Solutions, an H2 startup.

If we hadn’t had Covid-19, 2020 would be remembered for the Australian bushfire disaster, which killed thirty-four people and more than three billion animals, and for the unprecedented wildfires in Brazil and California..

Electrification

Yes, renewable electricity was making great strides, but electricity only accounts for 20% of our energy use. Even if we cleaned all of that up completely, using the sun and wind to generate clean electrons, we would still have the other 80% of the energy system to worry about. That’s the energy we use in transport, industry and heating, which today rely mainly on molecules from coal, oil and natural gas...

But there’s a limit to how much of the energy system we can switch to renewable electricity. Some sectors, such as heavy transport, industry and winter heating are particularly difficult for electricity to fully penetrate. The International Renewable Energy Agency (IRENA), sees electricity rising to just under 50% of the energy mix by 2050, which is wonderful, but still leaves another 50% to worry about. If we are serious about avoiding catastrophe, we need other technologies as well as renewable electricity – and we need them fast..

The model [forecasting an energy mix for a clean future] was forecasting that there was going to be a lot of cheap hydrogen for us to use because the cost of the renewable power used to make it was dropping fast, as was the cost of the equipment required to convert electricity into hydrogen. Transport costs were also assumed to be low because it would be delivered through already existing natural gas pipelines. All in all, the model predicted that by 2050 hydrogen would not only be the cheapest source of decarbonised energy for many sectors, it would actually be cheaper than what we are paying today for oil, coal and nuclear power.

That was a lightbulb moment, for me. I realised that hydrogen’s true mission was to help us harvest sunlight and wind where they were in plentiful supply, transport them cheaply, and get them into our aeroplanes, factories and homes. Just 1% of the Sahara Desert gets enough sunlight to power the whole world and hydrogen could finally give us a way to unlock that potential and decarbonise the hard-to-electrify sectors at the same time. Moreover, many people thought that the energy transition would mean rising energy costs and a need to support developing countries with billions of dollars. But the combination of cheap renewables and hydrogen meant we could envisage a net-zero world where energy was cheaper than it is today..

According to the World Health Organization (WHO), ambient air pollution kills more than 4 million people every year – twice as many as Covid-19 killed in 2020, and twice as many as are killed every year by malaria and tuberculosis combined..

Perovskites

One fast-improving solar technology uses perovskites, crystal structures first discovered in the Ural Mountains in 1839, which will reduce the cost of converting solar power into electricity. Films much thinner than a human hair can be made inexpensively from solution, allowing them to be easily applied as a coating to buildings, cars or even clothing. Painted on a substrate, or printed using an inkjet-like printer, they make an instant photovoltaic device. Perovskites also work better than silicon on cloudy days and even indoors. If the cost of this new technology falls far enough, solar power generation could unobtrusively move into our cities...

The remarkable rise of renewables is great news, but we can’t simply use clean electricity for everything we do. Solar and wind power are not constant. Batteries and other storage systems are limited, especially in the face of seasonal energy needs. In some industries and long-range transport, direct electrification just won’t work. Renewables are going to need a partner..

Batteries

Lithium-ion batteries have improved a lot.. but still they don’t hold much energy for a given weight. A kilogram of gasoline holds 13 kilowatt-hours (kWh) of energy; a kilogram of lithium-ion battery holds less than 0.3 kWh. This means electricity isn’t going to be the best way of powering sectors which need to take lots of energy with them. Just think of long-haul flying: we would need so many heavy batteries that the plane wouldn’t be able to take off. And batteries won’t compete with molecules to propel cargo ships across oceans. While for shorter distances battery-powered trucks look like a hot contender, for long-distance trucking, the amount of space and weight that the batteries would add (and the difficulty of charging them quickly) makes it hard to imagine their widespread use...

The Grid

Up to 8% of generated electricity is lost between the power station and your home. You can actually hear this happening if you’re close to a high- voltage power line – it’s that fizzing, crackling sound. You can also see it happening: as the metal cables heat up they expand, and begin to sag in the middle. That accounts for about a quarter of the energy lost. The other three quarters are lost, rather less spectacularly in the lower-voltage lines to our homes. These losses have never seemed too onerous, because we’ve learned not to transport electricity very far. In Italy, we are on average 25 km away from our nearest power station. By contrast, we are something like 1,000 km away from our main natural gas supplier, because it takes little energy to push gas through a pipeline [it will be same for H2]...

[O]ur hunger for renewable power means we will need to look further and further afield for our supply – especially if locally there are land constraint issues, or difficulties in reaching the required scale in renewable production in the required timescale. We are also going to want to access the cheapest places to produce renewables. That makes importing renewables an interesting idea. The question is how best to do so. High-voltage alternating current, as we’ve seen, loses energy along the way...

Intermittency is a challenge because the grid must always balance demand and supply... Almost as soon as you stop pushing, the current stops. So one hungry customer’s sudden demand for electricity has to be met more or less instantly, or else a brownout – a serious reduction in voltage – hits every customer fed by the same power line. * That contrasts with a gas network. When you put natural gas in pipelines, you can vary the pressure so as to pack it in more or less tightly, meaning that you have lots of flexibility to satisfy demand fluctuations without resorting to additional generation or storage [same with H2 pipelines].

[M]ost pumped hydro schemes need mountain lakes to site their upper reservoir, and such places are scarce. Smaller still is the number of such places you would want to build on: pumped hydro and areas of outstanding natural beauty are not a good mix. And, even if companies were to get permission and acceptance from local communities, who typically rely on the same water or land for their own benefit, construction is not particularly cheap...

Batteries have other shortcomings. They are made out of metals which are, today, extracted and processed in a limited number of locations. On top of this, lithium mining requires large amounts of water in often arid locations, and can lead to contamination of soils and rivers. And batteries are difficult to recycle well, so they may end up in landfill instead of being recycled at all, leading to more contamination...

But seasonality is a huge hurdle to full electrification. For the colossal amounts of energy needed to balance the grid across seasons, batteries are no use. They would be ruinously expensive. Europe consumes about 5,300 TWh each year for heating and cooling, most of it in the winter.

As we saw when looking at intermittency, the cost of storing energy in batteries is something like $120/MWh if you are charging and discharging over 300 times a year. If you want to store energy in July and release it in December, that would only be one cycle a year, which means the cost of electricity coming out of the battery could be hundreds of times the quoted figure. And if batteries are a no-go, so is pumped storage. There aren’t enough suitable mountain lakes to cover our seasonal swings...

The vision of an economy powered entirely and directly by green electricity has taken a fair number of knocks in the last few years, with net zero targets forcing us to think through all of the challenges of full electrification...

[We need] something that takes the spare solar power from the summer and stores it for winter, and provides dispatchable generation when needed. Something that can be transported like gas, linking regions and seasons, and allowing us to tap the desert sun and mid-ocean wind, wherever renewable power is most efficient and we have the most space to put it. Something that can be delivered through existing, robust gas infrastructure, reducing the need for massive new investments in the electricity grid. Something that can reach those hard-to-decarbonise sectors, which require different forms of energy.

We need a molecule.

Pipelines

A concern was that hydrogen could infiltrate the carbon steel that pipelines are made of, making them brittle. How rapidly that happens depends on the quality of the steel. The softer the steel, the more disordered its atomic lattice and the less damage an extra hydrogen atom can do. Happily, much of the pipeline grid in Europe is made from softer steel grades, where the process of embrittlement is very slow. They are also very thick, which helps. Snam’s engineers have now calculated that at least 70% of the lines in Italy are already ready to carry 100% hydrogen at a pressure equal or slightly lower than the one we use for natural gas, and remain safe for fifty years. Indeed, the technical specifications for making hydrogen pipes, of which there are 4,500 km in the world, 1 turn out to be largely identical to those used to make natural gas pipelines in Italy.

Where necessary, it is possible to update the pipework. Obviously, this is expensive, but pipes don’t last forever, and old parts of the gas network are getting replaced all the time. This is already happening in some places. The UK distribution network, for instance, is being replaced as we speak, from mainly wrought-iron pipes to polyethylene pipes, which happily can carry pure hydrogen.

Storage

The petrochemical industry in Texas need[ed] a continuous supply of hydrogen to its refineries and their solution has been to store it in caverns. The Chevron Phillips Clemens Terminal in Texas, for example, has stored hydrogen in a disused salt cavern since the 1980s. Meanwhile, in the UK, there are three salt caverns safely storing hydrogen... Underground gas storage involves compressing and injecting the gas into a cavity of some sort. Gas is released under pressure when needed. For natural gas, underground storage in disused fields is remarkably cheap, at something like $10/MWh even if you only use it once a year...

There are lots of other storage options.. [an] intriguing option is pipe storage. We already know that pipelines can hold hydrogen gas at pressure, but what’s to stop you from laying down a series of cheap, standardised pipelines with sealed ends and using them as storage? A kilometre of pipeline (of the same diameter and pressure that you’d use for natural gas) could hold approximately 12 tonnes of hydrogen.

Another clever idea is to line a rock cavern with a thin layer of steel. This has been done in Skallen, Sweden, for use with natural gas. It allows you to ramp up the storage pressure to 200 atmospheres, because the rock formation carries the main structural load, and would be cheaper and easier than a massive tank.