UQx Carbon101x 4.2.1.3 Marginal abatement cost curves - YouTube

In managing the carbon footprint of an organisation,

it makes sense to implement the lowest cost abatement options first…

But what does this mean?

And, how do you work this out?

In this video, we’re going to investigate “marginal abatement cost curves”, which

are a useful tool for comparing and prioritising different abatement options.

Consider this scenario: Your company wants to reduce its carbon footprint,

and it has two low-emissions technologies to choose from.

The first is a vehicle fleet upgrade, with a net present value, or NPV, of negative 200,000

dollars.

The second is a fuel switching project, with a net present value of negative 100,000 dollars.

Assuming you have capital constraints and can only implement one of these projects,

which abatement option would you choose?

Now, if you recall from the previous video, a negative net present value represents a

net financial cost over the project lifetime.

Therefore, in our example, the project with the lower NPV is more appealing.

That means you’d choose the fuel switching option, right?

Well, not necessarily, if we’re considering carbon management as a driver.

Net present value gets us halfway to identifying the lowest cost abatement options.

It helps us understand which projects have the highest financial benefits, but it does

not tell us about a project’s relative greenhouse gas reduction benefits.

Let’s assume the vehicle fleet upgrade has the potential to reduce the company’s carbon

footprint by 20,000 tonnes of CO2 equivalent, and the fuel switching project will avoid

only 5,000 tonnes.

Now which option will you choose?

From a carbon management perspective, your company is likely to want the most “bang

for buck” – that is, the most carbon abatement for the least cost.

Therefore, we need a way of relating NPV to carbon abatement, in order to know which projects

are most beneficial in terms of both their financial and greenhouse gas reduction performance.

And there’s a nice, simple metric for this: "Marginal Abatement Cost".

This is defined as “the average cost of reducing one tonne of carbon dioxide equivalent”.

It is expressed in dollars per tonne of CO2 equivalent.

Importantly, when the marginal cost is positive, then the cost to the company will be that

amount per tonne of CO2 e reduced.

When marginal cost is negative, however, it means the company is saving that amount per

tonne of CO2 e reduced.

A negative marginal abatement cost is therefore considered a cost saving.

This may sound confusing and counterintuitive, but it will become more clear shortly.

The cost per tonne of CO2 equivalent reduced is found by taking the net present value -

NPV (which you should have already derived from your financial analysis),

dividing it by the total volume of abatement the project will achieve over its lifetime and then multiplying this number by negative one.

This last part of the equation is important, as it translates a positive NPV into a negative

abatement cost saving figure, and vice-versa.

Going back to our example, this means the fleet upgrade has a marginal abatement cost

of 10 dollars per tonne of CO2 e, while the fuel switching project will cost 20 dollars

per tonne of CO2 e.

Now which project would you choose?

Well, now that we’ve factored in the projects’ respective abatement potential, the fleet

upgrade is the better option.

To visualise this, we can go one step further and develop a marginal abatement cost curve,

or "MACC", which looks like this.

Each box on the MACC curve represents a different project option to reduce greenhouse gas emissions.

Essentially, a MACC is a visual, economic decision-making tool that assists managers

to identify, rank and prioritise emissions abatement projects.

Let’s focus our attention on this biogas to energy project.

As you can see, a MACC presents two important indicators.

The X-axis gives us the volume of abatement that each project can deliver over our evaluation

timeframe.

Here, we can see that a biogas project will reduce the organisation’s emissions by 20,000

tonnes over the evaluation timeframe.

The Y-axis gives the marginal abatement cost.

In the case of the biogas project, the marginal cost is $16 per tonne of CO2 equivalent.

Once we’ve added all of the organisation’s project options to the MACC, these are ranked

from lowest (most desirable) to highest abatement cost per tonne of CO2 equivalent.

This produces the characteristic fan pattern that you see here.

Importantly, projects that present savings (that is, negative abatement costs) are positioned

below the horizontal axis, and should be prioritised for implementation.

Those that appear above the horizontal axis should, however, be evaluated carefully against

the marginal cost of other compliance options, such as buying allowances or offsets on the

carbon market.

For example, our biogas project has a marginal cost of $16 per tonne.

However, if offsets are cheaper at say $10 per tonne, then the organisation would first

choose to buy offsets, as they will save $6 for every tonne of CO2 equivalent when compared

to the biogas project.

So, in a nutshell, a MACC is a useful way to visualise and understand the internal abatement

options for an organisation, and compare their relative cost and climate mitigation performance

against other compliance options.

We will expand on this further in Part 4’s practical activity, where you will apply this

new understanding to build a MACC for your Tasland company.