Achieving net-zero emissions requires fact-based actions, not wishful thinking

The climate debate is characterized by many strong opinions, of which far from all are fact based. It is possible to become carbon neutral, but wishful thinking is not enough.

The world's energy consumption is enormous - the power consumption is a minor part of this

For many, the dream is for renewable energy sources to cover the entire world's energy consumption. Achieving this far from easy, and a major challenge in the climate debate is a lack of understanding of the enormous dimensions: It is difficult to comprehend how much energy the world uses! Power consumption is only a small proportion total energy consumption (see fact box).

As such, we must distinguish between power consumption which is about electricity and energy consumption which is about both electricity and heat. Most of the energy consumption takes place outside the grid, mainly related to transport and heating, including heat-intensive steel and cement industries that are difficult to electrify.

Energy consumption is so vast that Europe's largest wind project, Fosen Vind in Trøndelag, after the end of its lifespan of 25 years, will not have produced more energy than the whole world spends in five hours. Fosen Vind consists of 277 wind turbines, 221 km of construction road, and produces 3.6 TWh of electricity a year. This means that, to cover the world's energy consumption with wind power, five Fosen Vind must be built and disposed of every day – from now until forever.

Energy consumption will likely increase as we become more people, living standards are improved for the world's poor, and electricity becomes available to the more than 900 million people who do not yet have access. Electrification by using renewables and nuclear power can help limit this increase, because it provides higher energy efficiency compared to fossil fuels, where much of the energy disappears as heat loss.

Energy consumption by sources

Energy consumption by sources
Figure 1: Of the world's total energy consumption in 2019 (electricity and other), fossil fuels accounted for 86%. Electricity accounted for only 17% of the total consumption, of which 67% were from fossil fuels. Numbers are based on calculations using "direct method", and the figures will differ from reports that use the "substitution method". Sources: Our World In Data and Enerdata

Fossil fuel consumption must be reduced in a sustainable way

Fossil fuels account for as much as 86% of the total energy consumption in the world (Figure 1), and it is oil we use the most of, a whopping 100 million barrels every day, enough to reach around the equator and more if the barrels were placed one after the other. Still, this covers only a third of the total energy consumption. This means that a 100 million barrel oil discovery in the North Sea or elsewhere covers the global energy consumption for a meager 8 hours.

The Paris Agreement requires a reduction in the use of fossil fuels, but this must be done so that all people are ensured the right to a satisfactory standard of living, where hunger and poverty are eradicated, and everyone has access to reliable and modern energy services at an affordable price. A reduction of fossil fuel consumption therefore requires that the alternatives are present on a scale that makes it possible. This is not the case today, and in 2019 solar and wind power accounted for only 1.4% of the world's total direct energy consumption (electricity and more). In other words, we still have far to go.

The challenge is complicated by the fact that scaling up of renewables requires extensive and costly decentralization of the electricity grid, while the world's population is increasingly centralized in large cities. In addition, we must consider two of the biggest challenges in the transition to a low-carbon society, namely the high spatial requirements of renewable energy sources and variable electricity supplies.

Production of energy requires land

According to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), loss of nature is as big a threat as the climate challenge. High land use is thus one of the biggest challenges in the transition from fossil fuels to renewables.

All production of energy requires land. How much a country or region needs depends on the energy source, population density and energy consumption. Norway is one of the countries with the sparsest population density, only 14 individuals per square kilometer. This means that, despite high energy consumption, Norway spends an average of only 0.1 watts per square meter (see Table 1). The EU, on the other hand, has an energy consumption per area that is five times higher than Norway due to far higher population density, and in the UK, it is a whopping ten times higher.

High population density has consequences: This can be illustrated by looking at how much we get in return for the land the energy sources occupy - power density - measured in W/m2 (see Figure 2). Renewable energy sources are unfortunately far less area-efficient than non-renewable energy sources, requiring two to three orders of magnitude more land than fossil fuels and nuclear power, according to a study published in Energy Policy in 2018.

Table 1: Energy consumption in 2019 by regions, persons (kWh/day) and area (W/m2). The figures show actual consumption based on calculations using "direct method" and will differ from reports that use the "substitution method".
Figure 2: The power density says something about how much energy you get in return for the area used. Renewables have low power densities, which means much higher spatial requirement than nuclear and fossil fuels. Source: Energy Policy

How much land is available, and how much are we willing to sacrifice?

When we compare the power density of energy sources with the energy consumption per capita, we see how much of a country's area the different energy sources require. Land use is particularly problematic for countries, regions and cities with high population density, where land is needed for other things such as recreation, buildings and industry (including food production).

This challenge can be illustrated with wind power: If a fifth of Norway's energy consumption is to be covered by wind power, it requires 4,200 km2 of available area – far more than the entire Hardangervidda National Park plateau. Nuclear power would require 32 km2, and gas power 16 km2. In Norway, the discussion is not about food production, which in many countries can take place between the wind turbines, but about destruction of nature and visual pollution.

If EU were to do the same, i.e. a fifth of energy demand supplied by wind power, it would require 230,000 km2 (5.5%) of all available land - the equivalent of two-thirds of Germany. In the UK, the same calculation would mean that 11.5% of the land would be covered by wind power. It may sound manageable, but if we take away area used for buildings, protected nature and more, it represents a huge challenge, whether it's food production, visual pollution or loss of nature.

Of course, the wind turbines don’t have to be placed on land. They can be placed offshore, and the potential is huge, more than 15,000 GW (c. 60.000 TWh per year) according to the World Bank (current installed capacity is only 30 GW). Offshore wind is in an early development phase, and it is therefore uncertain how much of the potential that can be realized by 2050. In the roadmap to the International Energy Agency’s new report, Net Zero by 2050, it is assumed that around 10% of this potential will be exploited by 2050, something that corresponds to ten percent of the electricity consumption, or five percent of the total energy consumption, at that time.

Biomass requires even more land than wind power. If we use the median values in the Intergovernmental Panel on Climate Change's 1.5-degree report, which shows around a quarter of biomass in the energy mix by 2050, it will require more than the total land area within EU. Even in sparsely populated Norway, a third of the land will have to be used. The IEA roadmap is more moderate, but they clearly point out the challenges of increased land use.

Hydropower on a global basis is also very area-intensive (but significantly less so in Norway and some other countries with many natural reservoirs). Despite this, hydropower will be an important future contributor to the energy mix. The Intergovernmental Panel on Climate Change believes it is technologically possible to produce as much as 15,000 TWh per year. This is almost four times more than today's hydropower production. Nevertheless, it is far from enough, knowing that total energy consumption is already more than ten times higher, and is likely to increase further. The IEA's roadmap assumes a doubling of current hydropower, i.e. just over half of the technical potential.

What about solar power, which has the lowest spatial requirement of all the renewable energy sources? Solar irradiation contains more than enough energy to supply the entire world's population, but the challenge is to harness this energy.

The well-known, and now deceased, physics professor at Cambridge, Sir David MacKay, made a calculation in his book, "Sustainable energy – without the hot air”, based on rooftop solar panels. Such panels can produce up to 200 kWh annually per m2 at UK latitudes. He found that each person in the UK had an average of 10 m2 of south-facing roofs. If we assume the same in Norway and cover them with solar panels, it will contribute 5.4 kWh per day per person. Our total consumption is 172 kWh per day. Solar cells on roofs can certainly contribute, also in Norway, but the potential is limited.

For large-scale implementation it makes more sense, at least pricewise, to place the solar panels on the ground in solar farms, and there is little doubt that solar energy will be an important future source of energy, especially for countries with rich access to sun. This is also why the IEA's roadmap uses solar power to account for one third of all electricity production in 2050.

The challenge for Norway and other countries far away from the equator is the large difference in how much energy the sun delivers during different seasons, which comes in addition to day and weather variations. In Norway, the solar irradiation during winter is less than a tenth of what it is during summer (where the sun actually shines during winter time).

Geothermal energy is slightly less space-intensive than wind power and has potential in some places in the world with high subsurface temperatures, such as Iceland. However, most experts do not believe that geothermal energy will be anything other than a small contributor to the energy mix, and the World Bank estimates the total potential to around 500 TWh a year, while the IEA believes it is possible to install a bit more than this (820 TWh) by 2050. That is why geothermal energy is grouped together with other energy sources such as tidal power, wave power and other, which in total account for 0.4% of the current energy supply.

In total, the IEA roadmap assumes that 90% of all electricity consumption in 2050 comes from renewables. This is extremely challenging, not least with respect to spatial requirements. If we are to follow the roadmap and use the Energy Policy article on spatial requirements, an area equivalent to Norway will have to be occupied each year after 2030 for implementation of renewables. In parallel, the UN organizations UNEP and FAO are launching a global campaign to restore an area similar to China by 2030 to contribute to more food production, increased natural uptake of CO2, better resistance to climate change, as well as better environment and living conditions for millions of people. Following IEA’s road map, by 2050 we will have used almost as much area for renewables as that which is planned to be restored this decade.

We need stable power deliveries

The extent of renewables is steadily increasing, and solar and wind power have the fastest percentage increase (in actual numbers, natural gas increases the most). The challenge for these energy sources is that electricity must be delivered when we need it – all year round – regardless of whether the sun is shining, or the wind is blowing. Stable power delivery is a challenge for all energy sources that do not have steady access to fuel, such as coal, natural gas, biomass, and nuclear power. In their report, the IEA highlights energy security as a key risk aspect and believes that flexibility in the electricity grid must quadruple from today at enormous costs.

Energy storage becomes important, such as battery farms for storing surplus production from wind and solar. However, the batteries do not cope with seasonal variations, and in addition, it is expensive even if the price drops rapidly. Data from solar and wind farms in China show that the price of solar power will increase by 60% (2018) if lithium-ion battery farms are to replace the electricity demand for 4 hours, while the cost of wind power increases by 45%. This makes these options more expensive than all other energy sources. Furthermore, it is not possible as of now, either physically or economically, to implement battery parks on a very large scale, and therefore a technology revolution in battery storage is needed.

Hydropower can be used as a mechanical battery by pumping water back into the reservoirs. This is cheaper than lithium-ion batteries and is the most used mode of storage today. Such pumping power enables both short- and long-term storage of electrical energy, with the potential being limited by access to water reservoirs and acceptable level of natural interventions.

Chemical storage of hydrogen and the use of fuel cells will contribute to more stable electricity deliveries from renewables in the future, in addition to acting as fuel in the transport industry (see fact box). According to the IEA's roadmap to zero emissions, hydrogen production must increase sixfold and be generated mainly from energy-intensive electrolysis, which will require a fifth of all energy by 2050. In general, most storage solutions significantly increase the cost of power deliveries.

A contribution that reduces the need for storage is the establishment of international supergrids with power cables that cross national borders. For example, solar power surplus can be exported from sunny Spain to less sunny Norway when needed. Such grids are planned for in the EU, but the concept is not without challenges, illustrated by the dispute over the Northconnect power cable from Hardanger to Scotland. It will cost a lot, require local acceptance, and must be seen in light of the countries' own challenges of becoming self-sufficient with clean electricity – they have enough to deal within their own country. But supergrid certainly has the potential to contribute in the right direction.

Today, variable electricity supplies from solar and wind power are stabilised mainly by having access to alternative power plants that can be quickly adjusted when needed, such as natural gas, coal and hydropower plants. The challenge is that these are left unused much of the time, which increases costs and lowers the willingness for private investors to invest. In addition, fossil fuel power plants cause increased greenhouse gas emissions, which is a challenge for many countries with a high share of renewables in the energy mix, such as Denmark and Germany.

Decreased variability through energy storage, construction of supergrids, as well as flexible utilisation of alternative energy sources represent integration costs. These represent an important part of the overall picture when renewables share in the energy mix increases. A study in Renewable Energy shows that they can account for as much as 50% of the production costs of solar and wind power at high (40%) share in the energy mix. Integration costs are unfortunately often omitted in the cost discussion of renewables, thus misguiding the audience.

Renewables and batteries have high material throughput, including critical raw materials

The need for materials must not be underestimated when assessing the different forms of energy sources. Due to low power density, renewables use a large amount of materials, i.e. non-renewable resources, for the construction of the power plants. Parts of these are defined by the EU as critical raw materials, and they express concern about their availability. This is not least due to the fact that as much as four-fifths of rare earth minerals and metals are produced in China, who thus has almost full control over access. The power they have was illustrated in 2010 when China imposed export restrictions on rare earth elements, with the consequence that prices skyrocketed (Rare Earth Trade Dispute).

Batteries and electric engines use a lot of metals such as cobalt, lithium, neodymium and dysprosium. According to researchers at the Natural History Museum in London, electrification of the world's car fleet by 2050 will require annual production of neodymium and dysprosium to be increased by 70 percent, cobalt production increased by 350 percent, while world copper production doubles. In its net-zero emission roadmap, the IEA envisions a fivefold need for metals and minerals, while the need for elements such as nickel, cobalt, graphite and lithium must be increased dozens of times from today. The IEA is clear that this may not be possible and must be seen in light of human rights and political instability.

When it comes to material throughput in general, nuclear power uses the least materials of all energy sources. The material consumption of renewables is ten to twenty times higher, which means that a drastic scale-up of renewables requires tremendous growth in mining with the challenges it entails, and must be seen in light of the fact that it typically takes ten years or more to open a mine that will extract these raw materials.

The energy mix of the future must consist of more than renewables

Renewables will undoubtedly be a necessary and important contributor to the future energy mix. However, it is very difficult to envision that renewable energy will dominate already midway through this century. The IEA's roadmap envisages that two-thirds of the energy supply by 2050 must be from renewables to achieve the zero-emission target, but this must be seen in light of practical and economical challenges, as well as major negative consequences for nature and the environment.

However, it is not hopeless to achieve the zero-emission target, although probably not by 2050. To do so, we must be realistic, also in terms of the time it takes, and that we include two very relevant energy sources in the energy mix, namely nuclear and natural gas (in the long term with carbon capture and storage). Our opinion may be controversial, but the question is what is most important – to achieve the zero-emission target, or to exclude certain sources of energy because one "does not like them". All energy sources have their challenges, and it is largely about minimizing the disadvantages by looking at the totality.

Nuclear power has an undeserved bad reputation

Nuclear power is controversial, but this energy source is associated with the lowest greenhouse gas emissions, the land use is a fraction of renewables, the material consumption is by far the lowest, and it provides the most stable power supply of all energy sources – in stark contrast to solar and wind power. Health-wise, nuclear power is demonstrably at least as safe as solar and wind power.

Concerns about nuclear power are typically linked to the fear of accidents and the handling of radioactive waste. Nuclear accidents are admittedly the most expensive, but not the deadliest. That dubious "price" goes to hydropower, while wind power accounts for the most frequent accidents. To put that in perspective, traffic accidents cause as many casualties each day as the total historical number of casualties due to radiation from nuclear accidents. Modern nuclear power plants are also far more robust towards accidents than those built in Chernobyl and Fukushima, whose accidents resulted in a steep learning curve.

All energy sources produce waste, parts of which are classified as potentially harmful to health if not handled correctly. It is impossible to know what will cause the most casualties in the future from small amounts of very dangerous waste or large amounts of less hazardous waste - it depends on its handling. For example, nuclear and solar power have so far in history produced about the same amount of waste, around 250,000 tons. But nuclear power has produced over thirty times more electricity.

Going forward, solar power waste volumes will increase dramatically, and according to IRENA, the amounts from solar panels can reach 78 million tonnes by 2050, some of which are classified as hazardous waste in the form of indium, gallium, selenium, cadmium, tellur, lead and more. Nuclear power produces by far the least amount of waste of all energy sources.

A comprehensive new report prepared by the EU Joint Research Centre (JRC) concludes that nuclear power has many advantages and no greater disadvantages than renewables, and therefore should be incorporated into the EU taxonomy as a sustainable activity. The report has assessed the safety and management of hazardous waste in particular. Their conclusion is that existing nuclear power plants are as safe as renewables, while new nuclear power plants are even safer and have the lowest mortality rate of all energy sources.

The scientific panel also believes that the small amounts of hazardous waste can be handled properly by burying what cannot be reused in underground storage facilities. Should the waste leak in the distant future, the radiation doses will be far lower than both what is allowed and the natural background radiation, i.e. harmless. According to the panel, robust regulations mean that risk aspects related to weapons production and terrorism can be handled with the security procedures already established in the EU today.

Many claim that nuclear power is expensive, but their view often highlights extreme examples with long construction times and large cost overruns. While it is true that the construction costs of nuclear power have increased in some places, such as in the United States, they have fallen elsewhere, such as in South Korea. For costs, it is makes sense to use median or average values. Globally, there is no scientific support for the claim that these have increased dramatically over time. In any case, construction costs represent only part of the cost picture.

To say something about electricity prices, we must consider the full life cycle, and look at the total costs in relation to the total amount of electricity produced. The International Energy Agency (IEA) has done that, and their latest report shows that nuclear power in 2025 will be more expensive than solar and wind power if we ignore the cost of integration (something that should not be done), cheaper than hydropower and biomass, and cheaper than fossil fuels if the world agrees on carbon tax of 30 USD/ton.

Unfortunately, calculating costs is an imprecise science because there are so many complicating factors. However, when countries such as China, India, the US and the UK choose to invest in nuclear power, it tells a different picture than the one where solar and wind power are always cheapest. In addition, these countries are in need of stable electricity supplies and they value land use. This may explain why China plans to become the world's largest producer of nuclear power during this decade.

Nuclear power has nonetheless great potential for efficiency improvements, not least in Europe and the US, where much of the building expertise from the past is lost. When nuclear power had its heyday, the equivalent of 30 1-GW reactors was built in one year (1984). Had we repeated this, and started now, we could have tripled the current number of nuclear power plants by 2050, something that would be in the order that the Intergovernmental Panel on Climate Change believes is needed. Globally, nuclear power will like remain an important part of the energy mix, but this time it will not be France or the United States that sits in the driver’s seat, but rather China.

Looking at the total footprint on health, climate, economy, nature and the environment, nuclear power comes out with the lowest negative impact, almost no matter how you weight the different parameters (Table 2). This contradicts many people's opinion, but we believe this is an opinion guided more by emotions than facts. As such, we are disappointed that the IEA's zero-emission roadmap only envisages a doubling of the current nuclear power capacity.

And to make it clear: It makes little sense with regards to price, climate, environment and health to shut down operational and well-run nuclear power plants. Furthermore, if the lifespan of existing nuclear power plants is extended by 10-20 years, these will deliver by far the cheapest electricity.

Natural gas will remain important

Of all fossil energy sources, looking at negative impact on climate, health, nature and environment, coal is by far the worst with high emissions, high air pollution, high fuel consumption and much ash waste. Oil comes out better than coal, but still has high greenhouse gas emissions and pollutes a lot. Nevertheless, oil will be important in transport, heavy industry and heating until alternatives are in place.

Compared to oil, natural gas is cheaper, has lower emissions and higher efficiency, something that makes this energy source far better suited for electricity production. This is important in the upcoming transition where the world is to be more electrified. It is also important for Norway who, over the past twenty years, has moved through a transition from being an oil nation to becoming a gas nation. Today, Norway produces more natural gas than oil.

Gas from Norway is an important and cost-effective contribution towards achieving the zero-emission target because: Natural gas that replaces coal in power generation reduces greenhouse gas emissions by at least 50% according to a paper published in Nature Climate Change. We observe this when nations that increase their share of gas-fired power at the expense of coal experience a drastic decline in CO2 emissions. The US is a good example of this, and in the UK, natural gas replacing coal has been the main cause of the sharp decline in greenhouse gas emissions. Much of the gas comes from Norway.

In addition, coal-to-gas switching saves lives by reducing air pollution, which annually leads to the premature death of  seven million people. This is observed in China, where cities such as Beijing have introduced a ban on the use of coal and wood burning in their homes in favour of natural gas. By doing this, they have managed to reduce particle pollution by a third in five years.

Natural gas has at least as low overall footprint on climate, health, economy, nature and the environment as renewables if these parameters are weighted equally (Table 2). However, it is not a given that they should be weighted equally, and due to relatively high greenhouse gas emissions, it makes sense in the long term for natural gas power to be combined with carbon storage. According to the Intergovernmental Panel on Climate Change, this will reduce CO2 emissions by 80-90%, to a level lower than both hydropower and biomass. At that point in time natural gas is no longer just an option in a transitional phase but can become an important part of our future energy mix, thereby helping to satisfy the world's enormous energy needs.

We believe the transition will be very difficult or impossible without a significant amount of natural gas in the energy mix. The IEA's roadmap for zero emissions is based on a 55% reduction in current natural gas consumption, which suggests that natural gas will account for just over a tenth of the total energy supply in 2050. This is a halving from today, but because the roadmap contains numerous large challenges, we believe the world will benefit from using natural gas actively to replace coal, and allow a somewhat higher share in the energy mix in 2050.

The influence of energy sources on measurable parameters

Table 2: The influence of selected energy sources on quantifiable parameters. See for details and sources.

The zero-emission target is achievable if we listen to the facts

Much of what is written in this article is perhaps both unpleasant and controversial. However, this is what we need to deal with when establishing the energy mix of the future. Our view is that one of the most important things we can do, in parallel with implementing energy efficiency measures and accelerating the build-up of renewables, is to accept nuclear and natural gas as key contributors in the energy mix. These energy sources contribute to reduced greenhouse gas emissions, while at the same time having stable electricity deliveries with minimal consequences for nature and the environment.

We need to take this into consideration if the goal is to become carbon neutral in a sufficiently sustainable way.