MEVA – Advanced Vector Energy Model

Why the kilowatt-hour is no longer sufficient to describe the value of an energy vector

From Energy Measurement to a Multidimensional Representation of Energy Systems

The energy transition is profoundly transforming the way we produce, distribute, and use energy. The integration of renewable energy sources, the growing electrification of energy consumption, and the development of hydrogen, energy storage systems, and smart grids are making the energy system increasingly complex.

In this context, while energy measurement remains fundamental, it is not always sufficient to fully describe all the characteristics of an energy vector.

This consideration led to MEVA – Advanced Energy Vector Model, a methodological framework developed by Think Green Technologies R&D S.r.l. to represent energy from a multidimensional perspective.

The kilowatt-hour remains correct.

The kilowatt-hour (kWh) is the universal unit used to measure energy.

Its validity is not in question.

One kilowatt-hour of electrical energy and one kilowatt-hour of thermal energy represent the same quantity of energy, fully consistent with the first law of thermodynamics, which expresses the principle of energy conservation.

However, in engineering practice, two energy vectors that deliver the same amount of final energy may differ significantly in other respects.

For example:

• The amount of primary energy required to make them available;
• The technology used to produce them;
• The thermodynamic quality of the energy form;
• The capacity to perform useful work;
• The complexity of the energy supply chain.

The kilowatt-hour accurately measures the quantity of energy, but it does not describe the context in which that energy was produced and made available.

A simple example.

Consider a standard electric resistance heater.

From the device’s perspective, the conversion is extremely efficient:

1 kWh of electrical energy → approximately 1 kWh of thermal energy

The efficiency of the heating element is therefore close to 100%.

However, the picture changes when we consider the entire energy supply chain.

To make that kilowatt-hour of electricity available, a significantly greater amount of primary energy may have been required, depending on the generation system used, the national energy mix, and the losses along the conversion chain.

The heating element therefore remains highly efficient.

What changes is the energy context required to power it.

This distinction represents one of the fundamental concepts underlying the MEVA project.

Measuring Energy and Describing the Energy Vector

MEVA introduces a very simple methodological distinction.

Measuring energy and describing an energy vector are two distinct but complementary operations.

The kilowatt-hour continues to serve as the universal unit of measurement.

MEVA instead proposes representing each energy vector through three fundamental coordinates:

$$V=(E,\alpha ,\psi )$$

where:

• E represents the available final energy;
• α It describes the relationship between associated primary energy and final energy, as a function of the energy supply chain;
• ψ It represents the thermodynamic quality of the energy vector through an exergy indicator.

In this way, it becomes possible to integrate, within a single representation, information that is generally analyzed separately today.

The Model Coordinates

One of the innovative aspects of MEVA is the distinction between the inherent characteristics of the energy vector and those of the system that produces it.

Intrinsic Coordinates

They are inherent to the energy vector itself.

They include:

• available final energy (E);
• thermodynamic quality (ψ).

Contextual Coordinates

They instead describe the energy supply chain.

In the MEVA model, this information is represented by the parameter α, which expresses the ratio of primary energy to final energy.

In this way, it is possible to clearly distinguish the physical properties of energy from the characteristics of the system that makes it available.

Why MEVA Was Developed

The evolution of the energy system requires increasingly advanced tools to analyze scenarios characterized by:

• distributed generation;
• renewable energy sources;
• energy storage systems;
• heat pumps;
• hydrogen;
• smart grids;
• energy communities;
• electrification of industrial processes.

In these contexts, it is increasingly useful to compare not only the amount of energy available, but also the pathway through which it was produced and its thermodynamic quality.

MEVA was developed as a methodological framework to support this new approach to energy representation.

A Framework Open to Research

The model was conceived as an open platform.

Alongside the three fundamental coordinates, future developments may incorporate additional indicators, such as:

• environmental sustainability;
• resource availability;
• system resilience;
• economic indicators;
• overall supply chain performance.

The objective is to develop a descriptive language capable of keeping pace with the evolution of the energy system without altering the principles of thermodynamics or established energy engineering tools.