Our energy needs involve complex decisions with profound implications. One, already on the horizon, concerns hydrogen. The cycle of its production and use is deceptively attractive because it can be emissions-free, beginning and ending with water. Alongside that fact lies a hornets’ nest of negative features and a host of questions about how we plan our future.
The story of hydrogen is, literally, colourful. It is described as green, blue or brown, according to how it is produced. The brown version is made from coal or natural gas (methane) by separating hydrogen atoms from carbon atoms in a process called “steam reforming” and which releases CO2. This emissions-rich “brown” kind accounts for 95 percent of what is used around the world today.
If it’s blue, that same process using fossil fuels is said to incorporate the means of capturing and storing the carbon emissions. But this technology, known as carbon capture and storage (CCS), is expensive and undergoing further research.
Green hydrogen fits the initial picture of carbon neutrality if it meets two criteria: it must be made from water and the process of electrolysis used to produce it must be powered by renewable electricity.
Hydrogen of whatever colour is either compressed or liquified for storage and is used in fuel cells – where it is electrochemically combined with air to create electricity, which drives an electric motor. Water vapour is the only gas emitted.
Refining NZ currently produces brown hydrogen at its Marsden Point facility. In a submission to the Ministry of Business Innovation and Enterprise, of November 2019, it stated: “Replacing the brown hydrogen … with green hydrogen produced via electrolysis, would remove 500,000 tonnes of CO2 from New Zealand’s transport fuels.” This would be through rapid uptake of electric vehicles.
Hydrogen production has also been proposed as a use for surplus electricity following the closure of the Tiwai Point aluminium smelter.
Two other projects are already underway – one at Kapuni, Taranaki, and another near Taupo. Both claim their hydrogen as green.
At Kapuni a joint venture of Hiringa Energy with Ballance Agri-nutrients received $20 million from the Government’s provincial growth fund in March this year. Power will come from four yet-to-be built wind turbines. The involvement of Ballance is interesting since the hydrogen will also be used as a feedstock for the production of ammonia and the nitrogenous fertilisers which have, until recently, played such an important role in farming. But we are now discouraging their use because of the part they play in the pollution of our lakes and rivers.
Publicity for the project, however, emphasises hydrogen’s advantages for replacing diesel fuel in trucks and heavy machinery – and therefore as contributing to a reduction in our carbon emissions. The Government grant includes enabling Hiringa Energy to establish a network of eight hydrogen filling stations throughout the country, for FCEVs – hydrogen-powered fuel cell electric vehicles.
Halcyon Power, a joint venture of Tuaropaki Trust and Japan’s Obayashi Corporation, plans to start production early next year near Taupo, using power from Tuaropaki’s Mokai geothermal power station. (Whether electricity from geothermal power stations is totally emissions-free is disputed by experts.)
The involvement with Obayashi is significant because export of hydrogen to Japan features in Halcyon’s economics. A Memorandum of Understanding on Hydrogen was signed between the Minister of Energy and Resources, Dr Megan Woods, and her Japanese counterpart in 2018. Obayashi is the company involved in the construction of Auckland’s Waterview tunnel.
Japan still struggles to meet demand for electricity after the Fukushima disaster and the fact that hydrogen can be compressed or liquefied for storage makes it transportable. This is also why it is promoted for the electrification of heavy vehicles.
It’s true we have a problem. Trucks are said to make up only 4 percent of all vehicles but they’re calculated to contribute 25 percent of the transport sector’s emissions. We use them disproportionately to transport goods around the country because our railway is so undeveloped. We can’t electrify trucks and buses in the same way as cars and smaller vehicles because they would need enormous batteries and frequent time-consuming charging.
Hydrogen, carried in a tank like a gas cylinder, can last much longer and be refuelled quickly. This makes it suitable for long distance vehicles like buses and articulated trucks carrying containers. Switzerland produces green hydrogen using hydro power and is extending its fleet of hydrogen fuel cell-powered trucks.
So far so good. The big picture is way more complicated. Stored hydrogen is highly flammable and vulnerable in hot conditions. The hydrogen molecule is minute (as far as molecules go) and 1 percent is said to escape with every day it’s stored.
Hydrogen is an energy carrier, not a primary energy source in itself. This means that it requires outside energy at each step – for its production, then for its compression or liquefaction when it’s stored, and for its delivery and ultimate use. Moreover, energy is lost when the gas is converted to electricity by fuel cells. This voracious appetite has been aptly named the “parasitic” energy needs of hydrogen.
This aspect is made clear when the viability of energy is calculated according to the system used widely to compare the benefits and disadvantages of energy sources. This calculation is known by the acronyms EROEI, or more usually the shorter EROI. The former expresses the Energy Return On the amount of Energy expended, or Invested, in order to produce energy in its usable form. EROI can sometimes be interpreted to refer only to the financial investment – Energy Return On Investment.
Both values vary according to how they are calculated and what they take into account.
The EROI for fossil fuels has decreased as the availability of oil, coal, gas has reduced and the cost of production increased. Fracking for oil or gas (as has been done in Taranaki for years) is expensive and polluting. Extracting oil from the tar sands in northern Canada is a similarly destructive process. So, what was an EROI of 100:1 last century is now sometimes little more than 10:1.
Hydroelectricity has the highest value at 84:1, compared with wind at 18:1 and solar lower according to whether battery storage costs are included.
For hydrogen the EROI is 1:4 or 1:5. In other words, it’s demonstrably negative.
Nevertheless, it has its proponents, some of whom promote it as a more efficient way of storing electricity than lithium batteries. Others propose producing it in the down-time of electricity demand, in between the morning and night peak usage – the so-called “curtailment” time.
Still others foresee it as God’s gift to the airline industry but initial proposals grapple with the enormous storage tanks needed, which make relatively short distances only possible, and the problems of airport facilities for refuelling.
I fail to see how hydrogen can have a role in a future that is genuinely sustainable. Exporting it to Japan will do little for New Zealand except lock us in to a cycle of producing electricity from wind turbines for the benefit of Japan. Emissions-free FCEVs are not the answer to reducing our transport emissions. If we thought more carefully about the stuff we buy, where it comes from, how it’s made we would perhaps use less and what we do need could be transported on a massively increased electrified railway network. This would be to hubs from where goods could be collected by smaller, battery-electric vehicles.
A so-called “hydrogen economy” assumes we can produce renewable electricity inexhaustibly and thus, emissions-free, continue to lead our resource-depleting lifestyles. This is not the future we want. Our decision-makers in business and government need to come to terms with the issue of net energy – the amount that is left after the costs of production. Renewables are not a simple substitute for fossil fuels.
