5 ways of visualising emission reduction pathways

Many of our services involve the development of emission reduction pathways, which greatly enhance climate change action plans. In this blog post, we will show you 5 common ways to visually display such a pathway. Seeing these different illustrations can help you to shape how you would like to present your own organisation’s pathway towards a low carbon future.

Introduction

What are emission reduction pathways?

Emission reduction pathways allow for the easy communication of

  • where your organisation is currently at in terms of greenhouse emissions (or energy consumption)
  • where you can be through the implementation of reduction measures that are feasible and cost-effective over time
  • where you would be in the absence of any measures to reduce emissions

Pathways usually start with your selected baseline year and end at some point in the future, typically at 2030, or when agreed or proposed targets are to be met.

What do emission reduction pathways cover?

Boundary:

Your emissions boundary will typically consider three things:

  • The level of an organisation or region you want to assess in terms of emissions reduction. This could be a single site, an asset class (e.g. community buildings), a Division in an organisation, a whole organisation, a town or community, and up to State and National levels.
  • The emissions and energy sources that you want to evaluate. For example, electricity, natural gas, petrol, diesel, refrigerants, waste, wastewater and so on.
  • The Scopes of emissions you want to include. Typically Scope 2 (electricity) is included, and material Scope 1 emissions (on-site combustion or direct emissions). Selected Scope 3 emissions may also be included, such as upstream emissions associated with energy usage and waste.

Units of measure:

The unit for reductions or savings to be modelled will typically be tonnes of greenhouse gas emissions, or a unit of energy, such as kilowatt-hours or megajoules.

What greenhouse gas reduction measures are considered in abatement pathways?

For most organisations greenhouse gas reduction measures usually relate to six high-level carbon abatement areas as shown in Figure 1 below, being

  • Energy efficiency
  • Management of waste and other Scope 3 emissions sources
  • Sustainable transport
  • Local generation of renewable energy such as rooftop solar PV
  • Grid decarbonisation
  • Buying clean energy and/or carbon offsets

These high-level categories can be further broken down into as many subcategories as relevant within your selected organisation boundary.

Figure 1: 6 categories for carbon reduction opportunities

The need for a graphical representation of emissions pathways

For many people, it is hard to engage with complex data presented in a table or report. In our experience, it is most effective if abatement potential can be shown in a graph. The visual representation of a carbon abatement pathway allows people to better grasp the overall opportunity for abatement, where this will come from, and the timeframes involved.

It also helps organisations to better communicate their plans to their stakeholders, be they internal or external. Simple and well-presented graphics can also help when seeking decisions to budget for and implement cost-effective measures.

5 ways to graphically represent emission reduction pathways

There are many different ways you can display an emissions reduction pathway; some are more suited to specific circumstances than others. The five examples we are using in this blog post are:

  1. Line chart
  2. Waterfall chart
  3. Area chart
  4. Column chart
  5. Marginal Abatement Cost Curve (MACC)

Let’s look at these examples in detail.

Example #1 – line chart

A line chart is a simple but effective way to communicate a ‘Business-as-usual’ or BAU pathway compared with planned or target pathways at a total emissions level for your selected boundary. Such a boundary could be comparing your whole-business projected emissions with and without action to reduce greenhouse gases.

This type of graph is also useful to report on national emissions compared with required pathways to achieve Australia’s Paris commitments, for example.

Figure 2: Example of a line chart

Example #2 – waterfall chart

A waterfall chart focuses on abatement measures. It shows the size of the abatement for each initiative, progressing towards a specific target, such as 100% renewable electricity, for example. It is most useful to highlight the relative impact of different actions, but it does not show the timeline of implementation.

Figure 3: Example of a waterfall chart

Example #3 – area graph

Area graphs show the size of abatement over time and are a great way to visualise your organisation’s potential pathway towards ambitious emissions reduction targets.

They do not explicitly show the cost-effectiveness of measures. However, a useful approach is to include only measures that are cost-effective now and will be in the future, so that decision-makers are clear that they are looking at a viable investment plan over time to lower emissions.

Figure 4: Example of an area chart

Example #4 – column graph

A column graph is similar to the area graph but allows for a clearer comparison between specific years compared with the continuous profile of an area graph. In the example column graph below, we are looking at Scope 1 and Scope 2 emissions, as well as abatement in an organisation over a 25-year timeframe covering past and future plans.

In the historical part, for instance, we can see Scope 1 (yellow) and Scope 2 (blue) emissions in the baseline year. The impact of GreenPower® (green) on emissions can be seen in any subsequent year until 2018.

Going forward we can see in any projection year the mix of grid decarbonisation (red), new abatement measures (aqua) including fuel switching and renewables purchasing, as well as residual Scope 1 and 2 emissions.

Figure 5: Example of a column chart

Example #5 – Marginal Abatement Cost (MAC) Curve

MAC curves focus on the financial business case of abatement measures and the size of the abatement. MAC curves are typically expressed in $/t CO2-e (carbon), or in $/MWh (energy), derived from an assessment of the net present value of a series of investment over time to a fixed time in the future.

The two examples below show MAC curves for the same set of investments across an organisation. Figure 6 shows the outcome in 2030, whereas, in Figure 7, it is to 2040 when investments have yielded greater returns.

MAC curves are a good way to clearly see those investments that will yield the best returns and their contribution to your overall emissions reduction goal.

Figure 6: Example of a Marginal Abatement Cost curve with a short time horizon

Figure 7: Example of a Marginal Abatement Cost curve with a longer time horizon

Please note that no one example is superior over another. It depends on your preferences and what information you would like to convey to your stakeholders.

100% Renewables are experts in putting together emission reduction and renewable energy pathways. If you need help with determining your strategy, targets and cost-effective pathways, please contact  Barbara or Patrick.

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