Modelling each sector

The transport sector of the Global Calculator allows users to determine total transport energy demand and emissions using a number of levers. These alter the distance people travel, the amount of freight being moved across the world, and the type of vehicles being used. In the model, passenger and freight transport are considered as separate sub-sectors, each including all relevant transportation options including non-motorised (walking and cycling) and motorised transport (cars, buses, trains and planes) for passengers, as well as trucks, ships and planes for goods.

For motorised transport, the main technical options are considered, from traditional internal combustion engines, to hybrid, electric and hydrogen fuel cell vehicles. Biomass-powered transport is included in the model, but there is no specific lever allowing users to choose the amount of biomass used in this sector. Please see the section on land, bioenergy and food below for an explanation of how bioenergy is used in the model.

Transport is modelled according to geographical area type. The model splits the world into the following categories: 

• three types of urban area (automobile cities, transit cities and booming cities)
• two types of rural area (developed and developing)
• two types of international travel area (slow and fast growth).

Driving transport demand

Key drivers explicitly modelled to estimate transport energy demand and emissions are:

• population growth (which is the same as for the other sectors, and is a separate lever)
• the evolution of transport demand per person and the amount of transported goods
• the share of each mode of transport
• the technical choices for each transport mode in the future.

Other factors are modelled implicitly:

• the structure of the territory and the density of habitat in the various regions of the world
• as well as the geographical spread of economic activity. 

GDP growth and the wealth of households is not modelled explicitly in the tool: all levels 1 to 4 are designed to be consistent with GDP projections.

Transport and the economy

Transport is a key facilitator of other economic activity, and so impacts on many other sectors of the economy. Some of these interactions are modelled in the Global Calculator, but some aren't. For example:

• Goods transportation depends on the development of other sectors (for example, buildings and industry). Trajectories for these sectors could therefore influence the transport sector, but this is not explicitly modelled.
• Behavioural or technical changes could have unattractive consequences (for example, transport demand may rise if efficiency improves due to "rebound effects"). These are not taken into account directly but the user can simulate them by making appropriate lever choices.
• Changes in electricity demand in the transport sector will affect emissions, but these are included in the electricity production sectors in the model rather than the transport sector itself. Emissions computed in the transport sector are tank-to-wheel emissions only.

More information

GC Transport methodology.pdf

The buildings sector of the Global Calculator allows users to explore how the lifestyle we adopt in our homes and other buildings could influence global energy consumption and global emissions.

The buildings sector includes two components, residential and non-residential buildings. The residential sub-sector models urban and rural residents, and divides each of these into those who have access to electricity and those who do not. For the residential sector, the calculator models six kinds of energy consumption:

• heating
• cooling
• hot water
• appliances
• lighting
• cooking.

It then models the non-residential sector as a single unit, and models:

• heating
• cooling
• lighting
• equipment
• other energy use.

The calculator allows the user to choose:

• the warmth of our buildings in cold months and the heat in cool months
• the ownership of appliances and lighting
• the size of our buildings
• the "envelope" of our buildings (i.e. how well insulated they are)
• the technology we use for temperature control, cooking and lighting
• the efficiency of our appliances.

The user also chooses population and urbanisation, which drive the number of people within the four residential categories.

More information

Buildings methodology paper.pdf 

The manufacturing sector allows users to explore how the demand for materials and products drives global energy consumption and global emissions. It models the demand for products (e.g. cars) and then models the production of materials (such as steel) used in these products. It works in the following way:

• New product demand can be modified through three drivers: total product demand (which can be reduced), product reuse and product recycling. Total product demand is defined by action in other sectors, and by the "product lifespan and demand" lever.  Some of the product demand is modelled in this section, some is defined by the activity of the other sectors. Products are divided into around 15 categories (for example, "cars and light trucks").
• Once this amount of product demand is determined, products are manufactured using materials. The amount of materials required per product can be modified through three drivers: using less material through smarter design, using less impactful materials through materials switch, and reusing produced materials through materials recycling. Materials demand is segmented into 15 categories: oxygen (Hsarna) steel, electric steel, alumina, primary aluminium, secondary aluminium, high-value chemicals, ammonia, methanol, other chemicals, timber, pulp, virgin paper, recycled paper, cement, and other materials.
• Once the amount of materials demand is determined, the energy consumption and emissions can be modified through a series of around 60 industry-specific sub-drivers, which are linked to the main levers outlined above. These are grouped into the following four clusters: process optimization, fuel switches, energy efficiency and carbon capture and storage (CCS).

To keep the model simple, some interactions are not integrated, for example:

• The products’ consumption of the industry itself is not included.
• Emissions related to electricity production are computed in the electricity production sectors of the model. Emissions computed in the materials analysis are cradle-to-production emissions. The end-of-life treatment is only included when there is a demand for recycled materials.
• GDP growth and the wealth of households are not modelled explicitly in the tool: all levels 1 to 4 are designed to be consistent with GDP projections.

More information

• Manufacturing technical documentation 1 (demand for materials) (PDF 1.8MB)
• Manufacturing technical documentation 2 (evolution to 2050) (PDF 1.7MB)
• Manufacturing technical documentation 3 (existing studies) (PDF 1.9MB)
• Manufacturing complementary info.xlsx

The electricity and fuels sectors allow the user to explore how we produce the fuels and electricity that power our homes, cars, steel production etc. 

Electricity

The electricity sector works broadly as follows:

• The user decides the demand for electricity by choosing the level of activity in the transport, buildings, manufacturing and food sectors.
• The user decides on the supply of electricity from renewables, nuclear and carbon capture and storage.
• The Calculator supplies any shortfall from unabated thermal power (e.g. coal), or warns the user if they have oversupplied electricity.

The user can define electricity supply with the following levers:

• Whether power plants are powered by solid (coal or biomass), liquid or gaseous hydrocarbons.
• The technology of power plant deployed and the efficiency of the technologies.
• The capacity of carbon capture and storage (CCS), nuclear and renewables (wind, hydroelectric, solar and geothermal).
• The capacity of storage and the size of the demand peak.

The products’ consumption of the industry itself is not included.

Fossil fuels

The model then works broadly as follows for fuels:

• The user decides the demand for solid, liquid and gaseous hydrocarbons by choosing activity levels in the transport, buildings, manufacturing and electricity sectors.
• The user decides on the supply of bioenergy from the land, food and bioenergy sector.
• The calculator supplies any shortfall in hydrocarbon supply from fossil fuels. It works from final demand back all the way to extraction, accounting for the energy used in extraction, refining and distribution to estimate the total primary energy supply from fossil fuels.

The user can influence fuel production with the following levers:

• Specific energy consumption in oil extraction and refining, coal extraction and washeries, and gas extraction and liquefaction.
• Production efficiency of hydrogen through steam methane reformation, coal gasification and electrolysis.
• Split in hydrogen production method.
• Conversion efficiency in biomass pelletisation, dry biomass liquefication and dry biomass gasification.

The Global Calculator ensures there is never insufficient electricity supply to meet demand (explained on the energy balancing page).

The Global Calculator presents a novel methodological approach for the modelling of land use, bioenergy and food security, three sectors that interact because they all involve the scarce resource of land.

The Global Calculator applies a mathematical model to balance land for the production of food crops, livestock, biofuels and other bio-based products.  It allows users to simulate a number of trajectories of land use change and its associated greenhouse gas emissions, according to different demands for land-dependent products and services by 2050 using the combination of a number of levers. These include choices about diet, agricultural practices, and crop and livestock yields.

The model draws on several data sources, primarily the UN Food and Agriculture Organisation, International Energy Agency and Intergovernmental Panel on Climate Change statistics, and representative international references on land use modelling.

Food first, then bioenergy

Land use change over the period to 2050 is determined by the user’s choices using a hierarchy of land use types. The model is constrained by the total land available on Earth, excluding deserts, ice sheets and other non-productive land. Land for settlements and infrastructure presents a fixed trend in the model. After that, it is assumed that food security should be a priority over other uses (e.g. forestry and energy crops), which are then adjusted in the calculator to fill the remaining lands.

Thus, after allocating land for settlements and food (i.e. crop and pasture lands) based on the user’s choices, there may be a surplus land (remaining area). This could be because of substantial crop and livestock yield growths have been chosen and/or low calories and meat consumption levels. In this case, the freed up land can be allocated as natural regeneration, additional forest and/or energy crops using the “surplus land” lever.

In contrast, in some extreme situations (e.g. no crop yield growths due to strong climate change impacts, along with high food consumption choices), there may not be sufficient conventional land to meet food demand by 2050. In this case, agriculture and pasture would automatically expand over forest area in the model.

More information

• Briefing paper on land food and bioenergy (PDF 1.6MB)
• Definitions of land classifications (PDF 456KB)
• The Limits of Bioenergy: A Complex Systems Approach to Land Use Dynamics and Constraints by Alexandre Strapasson (on the Imperial College London website)
• Land Use Futures in Europe by Alexandre Strapasson, Jeremy Woods and Kofi Mbuk (on the Grantham Institute website) - briefing paper on land use in the EU using a methodology adapted from the Global Calculator

GGR comprises a number of technologies that aim to remove greenhouse gases from the atmosphere in order to limit the anthropogenic global warming effect. There are many risks and uncertainties associated with GGR, which vary depending on the technology type, its scale, public acceptance, energy requirements and environmental impacts. Therefore, GGR technologies are presented as something merely speculative in the Calculator, in a separate tab in the online tool. They should not be viewed as equivalent to the other GHG mitigation measures included in the calculator, due to the high level of uncertainties associated with them. The GGR technologies considered in the Global Calculator are:

• biochar
• direct air capture
• ocean fertilisation
• oceanic enhanced weathering
• terrestrial enhanced weathering.

Energy penalties for all technologies are also included in the calculations. The emissions associated with the energy input are calculated according to the energy mix chosen by the user.

Carbon dioxide can be removed from the atmosphere in other ways using the Calculator through afforestation/reforestation, bioenergy with carbon capture and storage (BECCS), and land use/soil carbon management according to the user’s choices. These are calculated in other sectors in the calculator.

More information

Briefing paper on proposed GGR techniques.pdf

The Global Calculator takes the amount of extra greenhouse gas emitted by 2100 in the pathway the user has chosen and works out the temperature change and other climate impacts using the latest climate science from the Intergovernmental Panel on Climate Change (IPCC). The Global Calculator does not include any "new" climate science.

Firstly, the relationship given by the IPCC's Fifth Assessment Report (2013) is used to derive a range of plausible global average temperature change for the given carbon dioxide emission level, adding a contribution from the other modelled greenhouse gases. This is displayed on the thermometer on the calculator's dashboard. The range of possible temperature outcomes is often several degrees; this is partly because of the limitations of climate science itself and partly because of the simplifications used in the Global Calculator approach.

State-of-the-art climate models are then used to visualise the possible impacts consistent with this range of temperature change, like regional temperature changes, regional precipitation changes and ocean acidification. These are displayed in the climate tab of the Global Calculator.

Variations on a theme

We have chosen to use outputs from a range of models so you can see the variety of projections that are currently available. In some cases they vary a lot because of the wide range of alternative projections about regional changes in circulation patterns. However, there are some very robust patterns which are found across all models, for instance temperature rises more over land than over ocean, and it rises more in the Arctic regions than anywhere else. There is greater agreement between models, and greater confidence in the result, for temperature changes than for precipitation changes.  You should think of these alternative model runs as a range of possibilities consistent with your lever choices.

Simple calculations

In the "basic physics" section of the climate tab you will find other climate results based on your pathway. These are the result of simple calculations based on the well-known logarithmic relationship between carbon dioxide and radiative forcing. These outputs are illustrative of the basic physics but are not quantitative projections. They are helpful because they illustrate that scientists' confidence in the global warming effect is derived not just from the results of complex climate models, but from an understanding of well-established physical relationships.

More information

• Animated maps methodology and discussion.pdf

The Global Calculator estimates the total capital, operating and fuel cost of the global energy system out to 2050. For example, it includes the costs of building and maintaining power stations, wind turbines, heat pumps, boilers, cars, trains, planes, roads, railways and the clean technology used in manufacturing, as well as the fuels, such as fossil fuels and bioenergy, used to power these technologies.

Our methodology for including costs in the Global Calculator has been guided by the principles that it should be simple and as consistent as possible with how other global energy models have done it. Since the Calculator does not have regional detail, we use US costs only. Many of our central estimates are US costs from the TIAM-UCL model. We also have high/low cost ranges.

More information

Global Calculator costs methodology.pdf