WELCOME to topic 4 OF THE Masive Online Open Course “DESIGNING THE ENERGY TRANSITION:
SIMULATION MODELS FOR THE DESIGN OF TRANSITION PATHS TOWARDS A SUSTAINABLE SOCIETY”,
This topic is entitled “Energy infrastructures and land use in MEDEAS” and this session
is dedicated to the first part of Topic 4: Energy infrastructures and land use in MEDEAS.
The contents of this video are related to the following modules of the MEDEAS model:
Energy Infrastructures, Materials and Land Use.
In Topic 3 we talked about energy sources: fossil as well as renewable ones.
We also said that in order to capture renewable energy we need to build up infrastructures.
The amount of renewable energy that we can extract in every moment is proportional to
the amount of infrastructures we have got.
When we talk about infrastructures we can refer to things such as solar pannels, windmills
or hydroelectric dams, but, in a wider sense, we can also talk about the equipment we need
to distribute the energy, or about thigs such as electric vehicles and batteries that serve
us to use electric energy from renewable sources in transportation.
There is a limit to the amount of infrastructures that we might have, since their building up
requires time and investments.
Materials might also pose a limit, since the amount of minerals in Earth crust is limited
and some technologies require minerals that are very rare.
The building up energy infrastructures requires, as well, spending energy.
This is the reason why we need to talk about the concept of EROI: Energy Return on energy
Investment, and, finally, energy infrastructures require land.
All of these aspects are going to be addressed in this session.
Topic 4 is divided in two sessions: Session 4.1 dedicated to Minerals, Transportation
and EROI; and sesión 4.2 is dedicated to land use.
This session starts with and introduction to topic 4 and describing what we call, in
a wide sense, infrastructures for a renewable society.
Fist, we talk about infrastructures for energy extraction and distribution
Then we will continue focusin on one of the most important sectors: transportation,
The fourth section is about mineral requierents for the energy transition
Finally, we will take a look at energy requierements for the energy transition, which is about
a crucial aspect: the concept of Energy Return on Energy Investment (EROI) by reviewing some
of the contents already seen in Topic 3.
Let us start with the first section: energy extraction and distribution.
In Topic 3 we talked about the renewable energy infrastructures in MEDEAS.
We showed they are modelled using several stocks for the installed, planned and required
capacity of production of renewable energies.
The main infrastructures considered are: Renewable electricity generation of 8 technologies;
Storage and distribution for electric renewable energies; Gas to Liquids and Coal to Liquids
conversion plants; and Renewable energies for heat.
Let us focus our attention now, on one of the industrial sectors that is a vital factor
in the energy transition: transportation.
The demand of energy for transportation in MEDEAS comes from different uses on one hand,
we have the energy demanded for households private cars on the other hand, the demand
of companies that transport goods and persons, which is divided into inland transportion,
air transportation and wáter and other transportation.
The energy vectors that move this transportation are mainly liquid fuels, most of them derived
from oil.
Only 2% of the energy for transportation is electricity and 7% is gas.
We know that oil is going to be the first fossil fuel to experimenting shortage, and
liquid fuels are not easy to obtain from other sources.
On the other hand, most of the renewable energy is electricity.
It is, therefore, desirable to change the energy vector of transportation from liquid
fuels to electricity or, eventually, to gas.
This can only be done if there is a change in the vehicles, and gasoline and gasoil vehicles
are substituted by electric, hybrid and gas vehicles.
This change can be done, more or less easily for private cars and inland transportation.
But it is technically very difficult to do for air and wáter transportation and, at
present, no such comercial prototypes are available.
Therefore, MEDEAS, considers the change in the type of vehicle for private cars and motorbikes
and for trucks, light cargo vehicles, buses and trains.
While in air and wáter transportation only general and limited improvements of the efficiency
are considered.
The MEDEAs Transportaion module works as follows.
We consider the percentage of vehicles of each type, for example electric cars, electric
motorbykes, hybrid trucks, etcétera.
The rate of change of this stock is decided by the user and it changes linearly.
For example: the initial percentage of –liquids cars is almost 100% today, while the percentage
of -electric, hybrid and gas cars is neglictible.
We can decide the final percentage in the final year of the policy so that the alternative
cars will grow and liquids cars will decrease.
MEDEAS model (at least al present version) does not consider social policies that change
mentalities or enforce cultural changes, such as the policies to promote masively public
transportation or bycicles, therefore, the total number of vehicles is determined by
the economic demand and the growth of the population.
The number of alternative vehicles is determined multipying the total number of cars times
the percentage of each alternative type.
This estimation of the number of cars enables us to determine the batteries needed and the
energy necesary, which is calculated via the energy intensity of Households and Inland
Transportation sectors.
In the excel file inputs_W the user can decide if these policies of vehicle substitution
are activated, the initial and final year fo the transition and the desired percent
of vehicles in the final year for households vehicles and for Inland Transportation vehicles.
Lest take a look now at the fourth part of this topic: mineral requirements.
Minerals are present on Earth crust in deposits of high concentration called mines.
These deposits are classified into resources and reserves.
Reserves are those technically, economically and legally feasible to extract.
Resources are greater: are those deposits that might, eventually, be extracted but,
at present, are not profitable or legal but resources might became reserves when the price
or the technology makes extraction viable.
Human beings extract minerals to use them in different technologies.
After use, some of those elements are recycled.
Both extraction and recycling require energy (normally, extraction more than recycling).
The massive use of fossil fuels has enable our society to extract many more minerals
than those that where available in past centuries.
But most minerals are not recycled, and, after use, they go to landfills where they end up
dispersing in soils or in the ocean.
Theoretically, those minerals could be concentrated again and used, but, according to thermodynamic
laws, this requires an enormous amount of energy.
Therefore, once minerals are dispersed, their recycling is not reasonable, and they are
lost forever for human technology.
At present, most minerals are not recycled.
In this figure, we can see the recycling rates of the most relevant elements of the periodic
table.
Only those in blue are recycled at rates higher tan 50%.
Many minerals that are used in electronics and renewable energy are no recycled at all,
like thithium, the lightest metal, very important to fabricate light batteries for electric
vehicles galium, indium and tellurium, used to obtain high performance photovoltainc pannels
or neodymium, used in the permanent magnets of wind turbines.
MEDEAS considers the availability of 58 materials, out fo them 19 are minerals.
They have been elected because they are the bulk of the raw materials used in the construction
of the 6 most critical technologies: Solar photovoltaic and concentrated solar power,
wind onshore and offshore, batteries for the electrical vehicles and electric grids.
MEDEAS calculates the demand of these materials for renewable energy and for the rest of the
economy, the policy that can be selectd by the user is recycling and the output information
are warnings that tell us when the reserves and the resources of a particular mineral
are depleted.
In the excel file inputs_W.
The initial and final year of the policies and the recycling rates of each mineral can
be selected.
In order to have a sustainable technology we should move from today’s picture of very
low recycling, otherwise the transition to renewable energies will deplete the reserves
and even the resources of some key critical minerals.
For example, a 100% renewable society in 2060 with no recycling policies will use 78% of
the reserves of copper, 135% of the reserves of Lithium
And will need an amount of Tellurium and Indium several times bigger tan the resources of
those minerals.
Some of these minerals could be substituted by others, but at the cost of loosing their
unique properties, and ending up with technologies with lower efficiencies and more land demands.
The fifth section of this presentation is about the EROI os the transition to a renewable
society.
As we mentioned at the beginning of this presentation, in order to capture renewable energy we need
to build up infrastructures.
And this requires materials and energy.
In fact, most of the energy required to set up infrastructures comes for the materials
used.
In topic 3 we gave a definition of the Energy Return on energy Investment (EROI).
The most commong way to calculated it is the static form.
Static EROI is the result of dividing the energy output of a infrastructure over all
its lifetime by all the energy needed to build and opérate it.
In MEDEAS we have calculated the static EROI of the most important renewable technologies,
based on their materials requierements.
The results are shown in this table.
We can see that some of them, such as biofuels, have enery returns very close to 1, which
means that the energy they give is almost the same they requiere, while others such
as wind, wind offshore, photovoltaic and solar CSP have higher ratios.
These ratios can be compared with the combined EROI of all the economic system at present,
which is higher in most cases.
But MEDEAS does not only calculate the static EROI.
The dynamic nature of our model enables us to into account a very important aspect of
the energy transition: as the stock of renewable infrastructures is set up energy is invested
in advance; and, once it is build, energy can be obtained; this means that we need to
invest energy in advance.
For example, if we want to increase the amount of energy obtained followind the pattern of
the right hand graph; we would need to invest energy in a pattern similar to the one of
the left graph, which is greater at the beguining when the infrastructure is built
The result of substracting the energy invested from the energy obtained might lead to curves
such as the one below, which, in the first yeas, migh even get negative.
In this case, the first years, renewable infrastructures are a net consumer of energy instead of a
source.
When this pattern is found, renewable energies became a sacrifice of present well being for
the sake of the wellbeing of the future.
This pattern is called “the energy trap”.
In MEDEAS, dynamic EROI is calculated dividing the output of energy obtained one particular
year from the whole system by the energy invested that year.
If the introduction of renewable energies is very fast we might find situations such
as the one shown in these graghs.
Let is asume that the percent of renewable energies in the elctric mix increases to 50%,
or 75% of 100% from now to 2060 In these cases the EROI of the whole energy-economy
system woul decrease much faster for the 100% renewable target thatn for the 75% or 50%.
The fast introduction of renewable energies if lowering the EROI of the society to very
low and dangerous leves, forcing the society to function with very low net energy.
Some argument that the mínimum EROI that can maintain a complex society is around 10
or 5, although these data are subject to many uncertainties.