How big can renewables get?

Framing the problem

The one thing that almost everyone agrees on around global energy (GE) consumption is that there are no easy answers.?Emotions run high about the future contributions of various renewables (R), fossil fuels (FF) and various types of nuclear energy (N).?They are the big three.?The only other parameter in the mix fundamentally to make it a big four, is energy demand reduction (DR), including efficiency, which is an equally controversial theme, many imagining it impossible.

1)?????Future GE = (R + FF + N) - |DR|

2)?????N+FF = Future GE – (R + |DR|)

3)?????FF = Future GE – (R + |DR| + N)

Probably the biggest questions we therefore face looking ahead, are how much we can reduce demand by, and how much renewables can actually increase by.?Because whatever the difference left over is, has to be either nuclear or fossil fuel (or an unmanaged energy crash).?So those are both big questions.

If we imagine that N+FF is something we want to minimise in equation 2) above, because FF combustion leads to increased anthropogenic global warming, and because nuclear options are quite expensive, then it is the renewables and demand reduction aspects we want to maximise.??If we imagine, that of fossil fuels and nuclear, that fossil fuels is the one we want to minimise most - then nuclear kicks in to address any leftovers and help minimise the left side of equation 3.

Demand reduction – the preferred first stop shop – but how realistic?

OK, demand reduction is a huge topic.?People typically imagine it is some bogie-monster from government telling them they have to stop life as they know it, without any assistance.??Actually there are a wide array of options that are possible - more at an infrastructure redesign level for cities, buildings, transport, agriculture, horticulture, energy distribution networks, and industry.?Changes at infrastructure level make it easier for citizens to choose options that use less energy, without compromising their core needs.?Infrastructure changes are long term things though, so there is a realism needed about how long they could take.?It could be the best part of a century to change such things.?That said, demand reduction is always the preferable option where we can manage it.?It reduces costs, and environmental impacts for everyone.?So it should be one of our highest priorities with energy.

People also get upset about the phrase demand reduction, when so many parts of the world still have relative energy poverty.?Demand reduction globally is a net term however, so what we need to do is allow for increase in poorer countries, while achieving a scale of decrease elsewhere that is more.?So global demand reduction is not incompatible with still allowing some increase for the poor parts of the world.??We can see this from the scale of emissions in the big economy countries of?Figure 1?(see original at?https://www.visualcapitalist.com/visualizing-global-per-capita-co2-emissions/)

One thing to note though, is that the moment we move from combustion derived energy, which wastes a lot of energy as expended heat, to electrical energy deployment, we become much more efficient.?About three times more.?That means wherever we can practically move from combustion to electrification it reduces the need for primary energy automatically.?Figure 9?later on shows the impact on what is theoretically achievable if we shift all our combustion supplied energy to electrically supplied.?No-one is suggesting that is going to happen, not imminently anyway, but it shows that big demand reduction is not such the impossibility we may imagine it to be.

Renewables Impact

In the interim though, while we sort out how to tackle that involved problem, what this article is primarily concerned with, is how much difference we can make with renewable sources.?As a spoiler alert, I’m not going to answer that question because I don’t know.?

Some say renewable energy is capable of replacing fossil fuels totally and quickly.??Others balk. Still others point to the environmental impacts that renewables can have – such as increased demand for some minerals - and say no that’s no good, and maybe there just isn’t enough of stuff to do all we want to do.

Figure 2?shows current global production of some key metals and ores, industrial metals, and technology and precious metals.?Note that some of these are ore, and some of these are produced metals, and comparisons in terms of mining impact really need to take into account the concentrations present in the ore – as that dictates what volumes have to be mined. A caveat to that is that sometimes a variety of useful minerals often occur together in the same ore, so adding all the ore volumes up has traps to avoid too. The story is a clear one though in the sense that?things like iron and aluminium and chromium and copper which are used widely across any industry, be it oil and gas or renewables or anything else, these dominate mining.?And coal mining (Figure 3) beats all of them.??Metallurgical coal (used in steel refining) just on its own is vast enough, at about a third of iron ore production.

Nothing though is without mining implications – oil and gas with its huge demands on steel and high temperature alloys for drilling and refining; similarly for geothermal; and renewables with various battery minerals and magnet minerals for motors/turbines.

These needs do evolve though, as do the ability to extract and process – they are far from static.?Even as everyone frets about lithium supply, moves are afoot to create batteries that use sodium instead, which is much more common.??Similarly, as everyone frets about rare earth elements or REE’s, used widely in electronics and permanent magnets of motors, the use of motors and turbines which don’t deploy permanent magnets are developing at pace.?None of these things are magic wands, and may have constraining caveats themselves - but it illustrates that today is not representative of needs for tomorrow. ?

The requirements for particular minerals can be strong, but as certain price thresholds kick in, so too does increased recycling or workarounds with other minerals.???To be clear, nothing is infinite, but neither are our current day processes and requirements necessarily representative of future requirements.?And while overall crustal abundance is a bit different from ease of extraction, it does tell the story that some things are much more common than others, as per Figure 4.? If something can be easily recycled, it also dramatically influences the sustainability of it, as opposed to anything that is single use only. That is no panacea, as recycling is never 100% efficient, but it helps. Recycling though is not always easy, and a number of criteria have to be met to do it efficiently, as per Figure 5.

But it’s relative...

Suffice to say then that nothing is without impact, and all these impacts have to be considered and accounted for.?Yet the impact of anthropogenic global warming is existentially threatening and proximal.?Further links to explore on that front are provided in:?https://www.dhirubhai.net/pulse/climate-change-what-actually-pre-requisite-action-why-dave-waters/

The scale of the problem is tremendous, and as expounded in Figure 6.?The onset of an adverse 2 deg C global temperature rise is expected to kick in at 450ppm, in about 15 years’ time, before 2040.?If all the known reserves of fossil fuel were burnt, the CO2 concentration would reach 1000 ppm, a truly horrific scenario, so whatever happens, we cannot think of burning all the oil and gas we know about.?We can still use it in other things, but not burn it all.?The thing to recall is not that we are trying to avoid CO2 concentrations that the planet has never seen before.?We are trying to avoid CO2 concentrations and rates of increase that a world population and its vulnerable food and water supplies have never seen in the 0.5 Ma history of the species.

Carbon capture, by the way, is not enough to address this problem, it provides no escape chute, as illustrated in Figure 7a and 7b.?It just slightly mitigates the problem. Once we have conquered the challenge of stopping increases, at some distant time in the future, maybe capture approaches involving soils, reforestation, wetlands and the like, will help to slowly diminish CO2 concentrations. Meanwhile CCS in conjunction with actively emitting facilities, is no real help in reducing annual emission amounts.?It just lessens the damage where these facilities are otherwise unavoidable through other routes.

The COP agreed target, thought necessary to avert runaway warming, is 80% reduction in fossil fuel combustion.??We can’t know exactly what that magic figure is, but there is no absence of clarity on which direction to head.??That much is clear. ?80% might sound impossible, but 2% reduction year on year for 78 years, is 80% reduction.?Not to suggest that is easily doable either, but it is to illustrate that slow and steady can reach these kinds of reduction eventually, how ever long it might take. ?Hopefully we can be more ambitious than that, and maybe even if we start slow, it will accelerate. We can’t however wait for it to be easy, to start.?

The question which arises therefore is simply how quickly we can make these transitions, with demand reduction, renewables, and nuclear, given that anthropogenic global warming waits for no one, and the rate at which fossil fuels are being burned means there is a clock ticking on a decade scale.

In one future scenario imagining, let’s envisage that demand reduction could tackle 35% of our current mountain over a century sort of time scale, renewables could tackle 40%, and nuclear 20%, with 5% left to fossil fuels +/- some kind of capture.?Removing the demand reduction component, that would imply roughly 60% renewables, 30% nuclear, 10% fossil fuels +/- capture making up what remains. ?Is that so undoable??

Perhaps, but these are the kinds of things we need to ask ourselves.?Twiddle those numbers as you see fit to your own imagining, but this is the variable optimisation we find ourselves seeking.?With gCO2e/kWh not being the only driver - there are others such as biodiversity and efficient land use and other pollutants, that all incur issues requiring optimisation too, but CO2 – is a big-ticket item.?

What is the story of the last two decades?

So, where are we then, with oil and gas and renewables???

As an aside nuclear is another fascinating evolution story, but that is for another day.??Suffice to say that the growth in nuclear is happening mainly in countries that are big economies and either heavily coal dependent or heavily dependent on oil and gas imports. Not, interestingly, the countries of the west that first developed it.?France, Korea, and Canada perhaps being exceptions. Proponents will argue about its costs, but I think everyone agrees it is not a low CAPEX option to do at scale and takes a while to set up at any meaningful contribution.?It won’t be an option for everyone, not least for reasons of social licence in some countries, notably Germany.

Returning to renewables then.?The problem is of course that while there are some baseload renewable energy supplies, such as biomass, biofuels, geothermal energy, and ground/water/air source energy, many of the other most easily deployable renewables are intermittent – either seasonally, daily, with the weather, or the lunar cycle.?These include hydroelectric, solar, wind, and tidal options.?This intermittency however, is something that can be tackled in one of three principal ways:

1)?????Energy storage, with myriad routes (it's not just batteries - see figure 13)

2)?????Distal energy transmission like the example of HVDC (the intermittency associated with renewables at a location, averages out more the wider you can spread the geographical collection net)

3)?????Clever juxtaposition and design of demand to tally with supply – juxtaposition in both geographical and temporal senses.

Such devices and methods have cost, in terms of time, energy, and finance, so they do not represent a panacea.?Simply finding the resources to do storage at scale for instance is not trivial or without environmental costs of its own.??Nevertheless these are options in the mix, and they are devices to help the deployment of renewables.??

So how are they doing then??Typically the bad news story that is presented is the one in Figure 8 – the global primary energy consumption curves.?Here we see of course how dominant fossil fuels remain – oil, gas, coal.?The small slither due to renewables, is currently about 7% each for both of hydroelectricity and other renewables, totaling ~ 14% together.?Nuclear is around 5%.?This picture makes the mountain look like a huge one to climb.?This however is where we need to think about efficiency of combustion. ?This topic is treated more in my article:?https://www.dhirubhai.net/pulse/infamous-chart-dave-waters/

To cut to the chase though, if we have something like combustion that can have energy efficiencies in the 15-20% ballpark and replace it with things that have efficiencies more in the 70% ballpark, then there is a lot of scope to reduce the absolute amount of primary energy we need.

Figure 9 tells this story.?These kinds of graphs emerged first when companies like the big oil majors wanted to understand fossil fuel consumption, so originally, they were presented in barrels of oil equivalent.?These days, with electrical energy supplies from both renewables and nuclear so much more high profile and increasing their total component, the energy units have typically been converted to terawatt-hours or exajoules or other equivalents.?However, recognising the different efficiencies of some these routes, some sources have taken to converting the more efficient electrical uses into an equivalent figure assuming oil and gas equivalent efficiencies.?Ostensibly to compare like with like.??Seems fair enough?

However, the result of that is to grossly inflate the amount of primary energy actually required, if our plan of action is to gradually convert to the more efficient routes - not the reverse.?This over-inflation of the problem is what is shown in the left side of Figure 9, with the shades of grey representing fossil fuels, and is commonly referred to.?However, the more interesting conversion route to think about, is what would things look like if we converted the oil and gas derived energy to electrically supplied efficiencies. What then would be the total primary energy demand???That is shown in the right side of Figure 8.?It’s still a big hill to climb, but not nearly as scary as the left side.??

Still, we have to admit that the total for renewables is still a small slither, for primary energy.?If we look back at Figure 8 though, there is a back-story here that is quite interesting.?Firstly, oil consumption is going down consistently, and most recently, gas has slightly too.?Coal remains the spanner in the works, but even it is not rising rapidly.?What we do see though is the rate of increase over the past two decades in the non-hydro renewables.?In 2000, the non-hydro renewables were around 1%.?In 2010, about 2.5%, by 2015 about 4%, and by 2022 about 7%.??In two decades, that is an impressive growth curve.??We haven’t really begun yet, to feed-in renewables into our new build infrastructures of transport and buildings, so there remains lots of scope for improvement.?

The picture is even more encouraging if we look at what individual countries have achieved, as shown in Figure 10.??Some countries are starting to achieve quite appreciable proportions of renewably supplied primary energy.?Perhaps getting above certain thresholds will always be difficult, and perhaps there is some sort of asymptote – but the size of the contribution is becoming non-trivial in many places.?

This is reflected also in Figure 11, which shows a handful of countries getting above 40%, and a very healthy bunch of around 30 countries getting above 20%.?This does raise the question in some places of whether renewably supplied is the same thing as sustainable, especially when large amounts of renewable energy are dependent on growing biofuels at the expense of rain-forests – as for Brazil. ?It shows the dangers of being obsessed with carbon alone - the carbon tunnel. Nevertheless it tells us that significant proportions of energy supply provision via renewables are becoming a reality in many places.?

Even more startling perhaps is that over 80 countries have increased their renewables contribution by more than 10% and just about half of those have doubled it, in this 22 year period - as shown in Figure 12.??

What to conclude?

So what to conclude from all this??There is no clear-cut indication or guarantee that renewables, in combination with demand reductions will be able to solve all these issues in sufficient time.?

Perhaps it is possible, and many respected engineers and scientists are suggesting so.?However, even if it were theoretically possible, what we know about the time taken to establish supply chains and obtain financing and planning permissions for changes at this kind of scale, suggests that there is at least a possibility and maybe a strong one, that renewables might not be able to fill the gap. Not at least in a timely manner relevant to global warming concerns.?So that places extra emphasis on the need to examine routes for demand reduction, including efficiency.??It also suggests that nuclear should be considered as a worthwhile route for ongoing R&D & deployment to cover the eventuality that there is a big shortfall in many places.?

In other words, some kind of location specific prioritisation is needed in every place to address the hierarchy of fossil fuel energy replacement.??I have had a go at one imagining of such a thing in Figure 13.?This is not something I present as “the answer”, it is just something I present as the kind of exercise we have to go through in each place.?List the options and with an emission (and other environmental concerns) driven prioritisation, and assess the order in which we are going to tackle things.?Cost will be an element of that, as will time to deployment.?So too will social licence in various places.??There is no one size which fits all.?And given the timescales required in many of the demand reduction options, this is an exercise that has to be undertaken on a century time scale.??

This is hard.?A wicked problem.?We may not have all the answers now, but we can formulate protocols to address such questions.??This is something which, amongst others, the Global Association of Transition Engineering (www.transitionengineering.org) speak eloquently about.?

What I think we can conclude, is that renewables are not to be ignored.??They are not without issue, but over the past two decades they have expanded at impressive rates. The opportunity to employ them with a deliberation that is new and a determination to ween off fossil fuel combustion - at the new build design "core" for everything - is something that has not really been adopted fulsomely anywhere yet.?

That means there is hope renewables can contribute a very useful amount to global energy uses, and emissions reduction.?Whether it is 100% of the eventual energy pie, 80%, 60%, or 40%, who is to know, but one thing is clear, a direction in which we can usefully travel is apparent.?Demand reduction, and renewables deployment may not be the whole answer, but they are great places to start.?