Don't expect the lightest gas to do the heaviest lifting, warns Lindsay Wood. Here he lays out how not all types of renewable energy are born equal – and how we can live well with less of it.
Have you noticed alternative energy options bursting onto our radar? Thomas Sattich called hydrogen “The energy transition’s current darling”, the Climate Change Commission’s advice to government flags significant roles for biofuels, and the forestry sector suggests wood derivatives are the answer to just about everything.
Of course it’s critical we pursue renewable energy if we’re to slash fossil fuel usage, and slash it we must. But while the above sources might be significant (and I benefit, running my campervan on 100 percent biodiesel), we must be realistic about what advantages they genuinely offer.
At best, we should see them as modest contributors to our decarbonisation journey. When the chips are down, we’ll likely find a much lower-energy society is not only our best, but our only, option. Which we’ll also find isn’t just bad news.
The University of Waikato’s Professor Troy Baisden took a measured look at biofuels, and cautioned “Any new biofuel production that isn’t from waste usually means we stop producing something that previously had value.” (In the October 15 Guardian Weekly, The Burning Question reinforced this, and other, concerns.)
Biodiesels also illustrate this, and they aren’t all born equal. Happily, New Zealand’s (from waste cooking oil and tallow) are among the best, with only 15 percent of the emissions of mineral diesel, and 25 percent of other biodiesels.
And the World Resources Institute has other gob-smacking data: “PV systems today can generate more than 100 times the useable energy per hectare than bioenergy is likely to produce in the future, even using optimistic assumptions.” Got that? We’ll get more energy from one hectare of photovoltaics than from 100 hectares of the best crops we can grow.
Baisden’s observations makes that gap wider: “Battery electric vehicles…are about 90 percent efficient, making the same energy go three times further than liquid petrol or diesel.” Which makes PVs charging EVs some 300 times as productive as growing biofuels crops for combustion engines.
But we shouldn’t totally dismiss biofuels: they do have a place, with the big caveat they must be from waste.
So what of hydrogen, our smallest atom, lightest gas, and highly reactive to boot (all of which make it a handful to control)?
Sattich poses three geopolitical questions, on the premise that “Only then can you establish where hydrogen might fit in the global energy mix.” However, without detracting from the geopolitical significance, he overlooks the quintessential question: what is the “net energy return” of electrolytic ('green') hydrogen? i.e. how much energy does it release compared to the energy invested in procuring it?
Sometimes termed “Energy return on energy invested”, or ERoEI, this is a huge elephant in the energy room, but one we habitually ignore (Sattich is far from alone).
ERoEI isn’t new: biology professor American Charles Hall has written on it for decades (such as his book “Energy and the Wealth of Nations”), Pat Bodger, as Professor of Power Engineering at Canterbury University, researched it in the 1980s, and energy economist Tim Morgan has termed ERoEI “the killer equation” because of its potency in shaping society. (Morgan foreshadowed our escalating debt crisis through analysing ERoEI.)
And, in Newsroom last year, Pat Baskett noted hydrogen was “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 ERoEI of hydrogen is in that hornets’ nest, and is dismal. While good hydro-electricity schemes might yield 100 units of energy for every one invested, and wind turbines around 20, hydrogen typically returns one unit of energy for every five invested (i.e. the system uses five units of energy to deliver one).
Like biofuels, electrolytic hydrogen becomes less dismal if produced from 'waste' which, in its case, might mean water otherwise spilling over a dam without generating. Even so, its feeble energy return means that, overall, it’s best suited to rare applications which add so much value that the huge energy wastage, and attendant emissions, are tolerable.
To a degree, Manapouri’s hydro-electricity might offer such waste' once the Tiwai smelter closes. However, with the daunting logistics of electrifying our entire economy (think a giant wind turbine every four days forever), using electricity to extract hydrogen, with its negative energy balance, makes little sense, least of all if it’s then exported offshore.
And 'green hydrogen' rapidly becomes 'dark grey' if its production uses 'grid average' electricity or, worse, prolongs Huntly’s or Fonterra’s use of coal.
Ulf Bossel, a global authority on hydrogen, wrote in 2005 “As the fundamental laws of physics cannot be changed by research, politics or investments, a hydrogen economy will never make sense.”
Which should prompt us to also check out biofuels. They are better than hydrogen but still nothing exciting, with ERoEIs generally under three.
So enter stage left Morgan’s “killer equation”.
It’s well-established that societies need energy with a good surplus (good ERoEI), supporting what Morgan terms a “surplus energy economy”. Energy-intensive civilisations like ours need an ERoEI of 15-25 (equals an energy surplus of some 95 percent), and even the most basic societies need around seven.
Which begs the question “what gives?” If energy transition’s "current darling”, hydrogen, has negative ERoEI and biodiesel only three, when our culture needs 20 and basic societies seven, there’s no way those energy forms can sustain even simple communities. Bossel’s conclusions suddenly stack up.
Wider analysis shows few renewables come even close to supporting our lifestyle. Wind turbines, around 20, have a marginal chance; photovoltaics (“buffered” for servicing peaks) are under seven; and firewood, while about 30, brings huge environmental and logistic downsides.
Geothermal varies but, like nuclear power (perish the thought), averages around a sub-optimal 10. And if we ignore the climate crisis and bet our energy future on fossil fuels, we find some offer better ERoEI (coal averages above 30), but overall they have declined for decades (with the global oil average now below 18, whereas old “gusher” oilwells were around 100).
The answer is simple: unless, suicidally, we prolong our fossil fuel addiction, we must learn to live well as a lower-energy society.
The good news is that needn’t be as awful or daunting as might first appear. We are so profligate with energy there’s lots to let go of, from the lunacy of rush hour congestion, to office blocks with all lights blazing as cleaners clean one room at a time. And, in lower-energy societies, biofuels edge closer to making sense.
Plus we can design things better, from ending urban sprawl to refining technical equipment.
Seasoned energy scientist Amory Lovins has long championed the “Negawatt”. In Auckland in the 1970s he explained how saving a watt was cheaper than generating an additional one. And his 2018 research at the Rocky Mountain Institute shows US energy savings spectacularly outstrip renewable generation by a jaw-dropping 30:1.
In what he calls an invisible energy bonanza, Lovins writes “Millions of small improvements over the past few decades - all the myriad fruits of careful engineering - add up to efficiency gains that now provide more global energy services than oil or any other fuel.”
So we can live well with far less energy. Our real challenge is to turn our mind to it.
Which takes us back to Baisden, who succinctly summed all this up: “The most beneficial solution is energy conservation.”
