Do this or don’t do that, everyone has an opinion on how to achieve net zero. Here, Dr Mike McDonagh asks (and provides answers) to the questions that seem to elude global policy makers concerning net zero. He asks if credible solutions or political hot air are on offer.
Net zero is a concept that is designed to reduce carbon-based emissions (mostly CO2 and CH4), to a level where a country’s greenhouse gas (GHG) absorption equals its generation. This article does two things – it asks the questions that seem to elude global policy makers, and also provides the answers to some unanswered questions.
For example: “Why should an undeveloped country retain its forests when it can provide a better standard of living for its population by farming the same land?”
This is typical of the questions that are causing the log-jam preventing non-G20 countries from implementing decarbonising strategies. You can understand this cynicism when you consider that the industrialised world has already decimated its own carbon sinks in order to pump out most of the world’s supranatural GHG emissions.
However, in a polar opposite view: “Is it feasible to ask hard-working citizens of a developed economy to turn the clock back and acquiesce to a drop in their living standards?”
Because these are political issues and the author is patently unqualified to enter that debate, the bulk of the article will concentrate on the technology proposals promulgated by all players in this field. It is hoped that understanding the consequences of following existing carbon reduction policies will point the way to better, cheaper, and faster methods of reaching a global, as well as local, net zero condition.
To illustrate this we need to answer one simple question: If we continue with the current decarbonising measures, what will be the consequences?
This article will demonstrate these consequences by straightforward arithmetic calculations and with minimum dependence on knowledge of the technologies described. It will then propose different approaches, with different solutions. The aim is to point out the hurdles to overcome for each of these policy measures, then to show the consequences, and provide alternatives.
Irrespective of personal beliefs about the reality, causes or effects of climate change, any proposed solutions need to be acceptable to those affected. If not, they won’t happen. The article has two aims: to demonstrate that there are quantifiable and verifiable consequences to the current measures to achieve net zero, and that there are better, possibly lower cost measures, that will achieve the goals faster with more acceptable outcomes. (Fig 1)
UK’s net zero policies
- Reduction of vehicle emissions – shift to private electric cars
- Use of renewables for energy generation, mostly wind, with solar
- Energy storage for variability in supply and demand
- Carbon capture from burning fossil fuels
- Reforestation to reduce emissions target.
It is important to point out at this stage that whilst most of the examples are based on the UK as a model, it is accepted that only a global solution stands a chance of providing the necessary outcome. Each policy measure will be examined in turn starting with traffic emissions.
Reduction of vehicle emissions
The current measure is to phase out ICE vehicles with the expectation that they will be replaced with EVs.
This is a very well documented topic; the technological aspects have been covered in this magazine over the past few years. I suggest the reader search on www.bestmag.co.uk for past articles on EVs, starting with ‘Are we there yet’ published in the Winter 2021 edition. The hurdles can be crystallised as:
- Driving range – related to energy density of the battery
- Safety – related to the chemistry of the battery
- Charging points – lack of charging infrastructure and power generation
- Fast charging – hurdles include battery management, power availability and charging method
- Price – a big factor, particularly in less developed economies, related to the battery cost and life, as well as the vehicle.
Putting aside the considerable battery R&D in progress, to improve battery performance and price, we are currently in a situation where the public uptake of EVs will require a car price compatible with that of an ICE (including maintenance), a range of at least 400 miles (genuine), charging times of less than five minutes and a battery that does not spontaneously catch fire. Again, without covering old ground, this situation is still a way off.
As we are aware, commercial figures for driving range are not obtained under real-life conditions. The total mileage estimates can be at least halved by low temperatures, use of heating, lights and air conditioning, driving at motorway speeds, hill climbing, etc. The installation of more and fast charging stations could provide an answer but what would be the consequences? (Fig 2)
Follow this simple example:
- Ten electric cars within a 10-mile radius are simultaneously connected to a fast-charge point
- Each car has a 100KWh battery and wants to put in 80KWh in five minutes
- For a 1-hour charge you need a power supply of 800KW, i.e. 0.8MW
- For a 5-minute charge this zooms up to (60/5) x 800 = 9,600KW or 9.6MW.
This power drain is more than the present UK Basingstoke power station can supply. In other words, we would need to start building far more power stations or energy generators than is currently imagined by the majority of the UK population, including government ministers. There are also many other considerations of battery materials’ supply, safety and recyclability. These are adequately covered in previous editions of BEST.
Energy storage can partially resolve this, but it would not be the main part of the solution.
If we wish to operate predominantly electric road transport, then we need to reduce that traffic. The measures to take are as follows:
- Electrify and upgrade the railways. This reduces the need to use cars for long distance travel. Increasing the frequency of trains and the number of destinations will provide better incentives to ditch the car and travel long distances, hassle and accident free. (Fig 3)
- Improve public transport with electric buses and trams. Even self-drive or autonomous electric rental cars could be available at stations and in cities. Although the majority of us may hate them, proper use of electric scooters may help. Electric two wheelers would be particularly attractive for those living in terraced houses and apartments if they were to charge their vehicles indoors.
- Shift heavy goods from the road to the rail sector. Electric lorries and vans could be used to collect and deliver locally to and from rail loading centres. This would obviate the need for higher driving range and the expensive government backed R&D expenditure to improve battery energy densities. HGVs could take a variety of battery types and sizes due to their size and non-passenger function.
- Statistics show that the majority of domestic cars travel on average 142 miles per week, the majority of journeys are fewer than 10 miles per trip. For most EV owners, their battery packs could be reduced in size or even use cheaper technologies to reduce the EV costs.
- Public charging outlets would be reduced, both in quantity and output due to fewer outlets with lower power requirements. This would reduce the pressure on provision of more power generation. For electric HGVs, businesses would set up their own charging stations in suitable locations for their operation. Town and city driving uses considerably less power than motorway driving so the need for charging points would be minimal.
- Residents in cities of undeveloped economies do not necessarily need to travel long distances, and generally do not do so. Commuting with small EVs, scooters and bikes with workplace charging points would be a feasible option. The lower cost of short distance vehicles with smaller EV packs or cheaper alternative battery chemistries could be a major incentive for these societies to transition from fossil fuel to electric power.
Renewable energy generation
Several popular technologies are currently being promoted:
- Wind turbines
- Solar panels
The wind turbine is the most prolific and fastest growing renewable energy generator because of its cost. The most common size is 2KW and is often quoted as costing $1.3-1.6 million per MW of power. In fact, it is the cheapest of all grid-scale renewable power sources. It is also readily available with an established commercial infrastructure. In addition, many governments are offering incentives (paid for by the consumer in green energy tariffs) for wind farms to be built on land and at sea. For these reasons it has proliferated in most countries. (Fig 4)
Most renewables-based technologies have the major drawback of inconsistent operation. For solar, daylight and sunshine can be in short supply in much of the energy-hungry world. For wind, you cannot predict when the wind will blow. For wind turbines, the technical conversion efficiency is 20-40% (according to the EPA).
However, normal efficiency losses that occur as a result of the science, chemistry, or physical attributes of the system are increased tremendously by the lack of generation during a given period. In the case of wind, it only blows on average 30-40% of the time. This drops the conversion efficiency drastically.
Efficiency is also site-specific; turbines will be clustered at favourable sites and, dependent on your point of view, may be seen as a serious affliction. This impact is not just limited to humans, there is evidence of disturbance to migrating birds in both autumn and spring.
For solar panels there is the inbuilt inefficiency of the photovoltaic cells (20%) along with the day/night and cloudy weather problems. The efficiency gets progressively worse the further away from the equator that you move, i.e. the angle of incidence with the sun.
Hydro and ground heat pumps have been covered in various BEST articles and can be accessed via www.bestmag.co.uk. By and large, dams and ground heat pumps are expensive to install and can be disruptive to local areas. Dams change water courses, change local topography and have been shown to slow down the earth’s rotation. Yes, this assertion truly has been calculated by credible sources – you can read about that in BEST article ‘Dam or be Damned’ (Spring 2022). Both are not cheap in terms of $/MW generated and require considerable capital investment to get started.
Whilst wind power sounds like an instant ready solution for meeting net zero targets, and thereby securing government popularity, there are consequences. The first relates to how many turbines would be needed to fulfil a country’s energy policy (if one existed). As an illustrative device we can consider using wind turbines to initially fulfil a country’s entire peak period energy demand, then look at the effect of reducing this target.
Sticking with the UK, the peak demand for electricity is near 70GW. If we add in gas, the total peak energy demand increases significantly. Taking a simplified but reasonably accurate picture of peak power demand (gas and electricity) in the UK we can make the following calculations:
- Total peak electricity generation = 65GW
- Direct peak gas usage = 215GW.
To entirely replace the UK’s peak demand for gas and electricity, the number of wind turbines, at 2MW output, is 280GW/2MW = 140,000 wind turbines. The standard spacing for these turbines is approximately 3-4 times the blade diameter. This works out at around three or four per mile.
If we assume these farms are all offshore, this gives us a total linear distance of 35,000 miles. (Fig 5) However, we can expect the average output to be 25% of 2MW (source: EPA), which means that we need four times that number, i.e. 560,000 turbines and a distance of 140,000 miles. This would stretch roughly 12 times around the UK coastline of 11,000 miles. This is the starting point of course. Some farms are on land, others will be clustered offshore in more wind-efficient locations. Naturally, there would (hopefully) be a high degree of energy storage deployed and also the energy policy would deploy wind power as part, not all, of the solution. But this extreme example shows the need to have a plan that understands where the strategy is leading us and what are the consequences.
Assuming we have a balance of wind, solar, hydro, nuclear and tidal, combined with energy storage, then the unreliable elements of wind and solar power could sensibly be confined to 30% of the total peak demand. Not only would this save valuable land and sea territory, reduce the visual pollution of national beauty spots and our general national ambience, it would also save on materials’ resources.
However, even at this reduced level there would be significant materials supply challenges. To illustrate this, there are around 150 tonnes of steel, 600kg of the rare earth metal neodymium (used in the generator magnets), plus other, relatively scarce rare earths such as dysprosium, used in the electrical supply. Depending on the national strategy, this could amount to 100,000 tonnes of neodymium and 26.88 million tonnes of steel for large wind turbines. This is roughly the total world reserves for rare earth metals (Rare Earth Reserves: Top Eight Countries (Updated 2022): investingnews.com). Currently, China produces 98% of the world’s rare earth metals, making those metals “the most geographically concentrated of any commercial-scale resource,” (Kirchain). No anticipated problems there then.
As you would expect from a battery technician, I am advocating that energy storage is required to drastically reduce demand for generation from renewables and also for peak demand supply. Energy storage and distribution is a major factor here.
Just looking at current figures for the UK, we have a national peak electricity demand of 70GW, for about four hours per day. For the other 20 hours we have a cruising load of around 28GW. This is a total energy requirement of 70GW x 4h + 20GW x 28h = 840GWh per day. Spread over 24 hours, this would be 35GW continuous output. On average, in 20 hours, it would generate an additional 20 x (35-28) = 140GWh of stored energy. This additional energy could be released from the existing BESS technologies (Fig 6), at a rate of 35GW for the four hours a day required to meet the 70GW maximum. This means that with a national energy storage capacity of just 140GWh (7GW x 20 h), we only need to have an installed power generation capacity of 35GW.
In other words, with existing and cheap battery energy storage chemistries, we could halve the UK’s current total electrical generation.
Looking ahead, the total electrical requirement with a 50% EV take-up reduces from 100GW to around 65GW, which is still less than the current UK electrical power generation requirement. This would be a truly remarkable achievement; all made possible by battery energy storage. This is a very elementary calculation; any other factors such as supply efficiency, maintenance and downtime etc. will increase this figure, but it will be a low percentage increase. I hope that this analysis has clearly and simply shown that using existing battery technologies is the most important part of our energy strategy.
Other renewable energy generators could be considered as alternatives to wind and solar. Tidal power is another viable energy source, but is woefully underdeveloped. There are, rightly, objections to traditional barrages and tidal lagoons based on cost and damage to marine life. However, emerging technologies relying on tidal kinetic energy and free flow rather than capture are gaining commercial interest. Basically, these are based on undersea turbines that use water currents from coastal or deep estuary streams, to generate respectable levels of power. Pilot schemes are trialling up to 2MW from a single installation (Scotland, Spain etc.) Both horizontal and vertical axis turbines are under investigation with excellent results.
Whilst tidal power is the most reliable and predictable of all renewable energy sources, based on the relative movements of the Earth, Sun and Moon, it cannot guarantee to deliver at the right time to meet energy demands. For this reason, yet again, it is necessary to have energy storage integrated with all renewables-based energy generators. (Fig 7)
One of the tools in the shed of carbon reduction technology is the ability to capture CO2 as it is emitted from a fossil-fuel energy source. Recently this has been extended to sucking CO2 out of the atmosphere without linking it to a combustion process. Artificial methods rely on capturing and storing CO2 to remove it from the atmosphere. This is a large topic with rapidly emerging technologies. The various methods will be discussed in later articles. For now, we can say that present costs are $25-52/tonne of CO2 and there are two routes – storage in containers and reuse via carbonated beverages. The main disadvantage of these methods (financial considerations and future toxic waste sites put aside) is that they do not capture carbon; they capture carbon dioxide. This means that for every 12 tonnes of carbon removed, we also take out 32 tonnes of oxygen from the atmosphere. (Fig 8)
Not a good idea. For this reason, we turn to a technology that has been hundreds of millions of years in the making. It already exists and was in plentiful supply until we reverse engineered these machines by burning them and releasing the stored carbon into the atmosphere. Yes, I am referring to that natural biological engine – constantly absorbing CO2, releasing oxygen and storing the carbon via photosynthesis – the tree. This free engine provides a far better ROI than our physical methods of carbon capture, and it generates oxygen!
The net zero emissions target also needs to take into account the biomass available. It is the arithmetic sum of the amount of GHGs generated, minus the amount absorbed. Again, some straightforward numbers give us a reasonable idea of the amount of carbon removed from the gross emission figure by trees alone. According to the UK’s Forestry Commission, there are around three billion trees in the UK. On average, a mature tree will synthesise around 21kg of CO2 per year.
Taking our current emissions as 455Mt CO2 per annum and dividing by 21 kg, we get a requirement of 2.12×1010 or 21 billion trees to get us to carbon neutral. We can deduct the three billion that we already have, leaving a mere 19 billion trees to plant in order to suck up all the current CO2 emissions.
Apart from the logistics of the planting exercise, how much area would be needed to accommodate this extra forestry? According to the Centre for Sustainable Health Care (nhsforest.org), typical forestry planting densities are around 2,000 trees per hectare. To plant 19 billion would need 9.5 million hectares of land, or the equivalent of 11 North Yorkshire counties’ worth, or more dramatically, close to one half of the total UK land area.
Dare I mention that the survival rate of saplings could be as low as 20% if measures are not taken to reduce damage from vertebrates, invertebrates and disease? Luckily there are other carbon sinks including grasslands, heaths, hedgerows, coastal tributaries and surrounding seas that also contribute.
We are also reducing emissions to reduce the burden. In all we can expect the number of trees required would be reduced to about one quarter of this value if future emissions were halved and other natural carbon sinks are undisturbed. In this case we need only plant a further five billion trees by 2050, which is a mere three North Yorkshire-sized areas. The planting rate, however, would need to be around 167 million trees or 83,000 hectares per year. This compares with the UK government’s scheme of 30,000 hectares per year.
Another problem is the 21kg absorption per annum for one tree is based on a mature tree with at least 15 years’ growth. Trees planted later would be relatively ineffective. In all, it means we need to reduce our emissions by a lot more than 50%; in fact, it should be closer to 90% by 2050 to balance our likely tree population.
As is often pointed out (and just as often ignored), aiming for individual net zero targets is not only short sighted, it is nonsensical. The first stage in carbon capture is to ensure that present deforestation activity in emerging economies is not only stopped, but reversed. Latest reports of deforestation tell us that an area of rainforest the size of Portugal is chopped down and burnt each year.
The barrier to stopping this of course, is the powerful argument that these countries have the right to improve their population’s standard of living (Fig 9). In fact, broadly mirroring the way in which the developed economies have already done.
The last climate summit concluded that some compensation has to be considered as a financial incentive to encourage emerging economies to participate in a net zero programme. Raising funds to help countries move to low carbon economies has always been part of the COP meetings and is separate from the loss and damage fund agreed at the last COP 27.
Unfortunately, as pointed out by some delegates, financial incentives to encourage emerging economies towards net zero will most probably not reach the right target area. However, there was general agreement that something must be done to prevent the destruction of the planet’s lungs. Yes, everyone says that, but have they said the following?
Pay countries for the oxygen they produce
Think about it. Burning fossil fuels requires two elements of combustion, carbon-based fuel, plus oxygen. O2 is every bit as necessary as carbon to utilise fossil fuels in our everyday activities. In fact, for every 12 tonnes of carbon consumed there are 32 tonnes of oxygen taken up.
Why do we pay for the C-based fuel and not the oxygen used to ignite it?
Simple: unlike oil or gas, you cannot withhold or contain oxygen from trees in order to demand payment for it.
What you can do is to measure the existing forest areas of the countries that would be receiving payment. Provided the forest areas (and other CO2 sinks if needed) are registered by satellite images, then the payments would be based on the area of those features.
The attraction of this suggestion is that the more a developing country does to improve its O2/CO2 balance by stopping forest destruction, or even replanting it, the more it gets paid. That way, it no longer becomes a debate about charity and merit, it now becomes a straightforward commercial contract of demand and supply. It would also be simple to police in order to ensure that the money is correctly targeted. Satellite images would clearly show if forest areas were dwindling or expanding and could be used as a measure for amount paid.
This payment would at least partially replace the promised aid packages already allocated to these countries. Funding would, of course, be from the usual G20 members, probably structured on their individual carbon emission profiles. Even WTO trading tariffs could be levied along the same lines. In any event, all morality, righteousness and virtue signalling are removed.
The advantage for the richer countries is that it makes their present tree planting scheme a more realistic project than it currently is. It also means that the expensive and controversial CO2 capture requirement can be reduced. This is another example of why CO2 reduction should be treated as a global and not a local project.
The barrier of course, as always, is politics. The burden at the moment is on technologists, such as our readership, to find scientific and engineering methods to meet goals, rather than the economic and political solutions that we so desperately need to enable our already adequate technological advancements to be properly deployed.