Technology

Hydrogen: Clean and Convenient Energy

What is hydrogen and why is it important for clean energy?
Hydrogen is the lightest and most abundant chemical element in the universe. It is not a source of energy like the sun or wind, but an energy carrier: it stores and delivers energy when it's needed.

How to produce it?
Electricity is used to split water molecules (H₂O) into hydrogen (H₂) and oxygen (O₂). When electricity comes from renewable sources like sunlight, the hydrogen produced is called green hydrogen. This process needs only water and solar power—no CO₂, no pollution.

Why is it considered clean and convenient?

When you use hydrogen, the only “waste” you have is water
It can be stored and transported, unlike solar or wind energy which must be used immediately.
It’s suitable for industries, transport, and residential use.

How to use Hydrogen to generate energy?
Hydrogen can be 'reactivated' to produce energy through a device called a fuel cell. Inside the cell:

1. Hydrogen combines with oxygen
2. It produces electricity, heat, and water

It’s like a small power plant without smoke or combustion.

Fuel cell efficiency: around 60%
Latest-generation PEM electrolyzer efficiency: about 75%
Total system efficiency: around 45%

How is hydrogen stored?
Hydrogen can be compressed and stored in high-pressure cylinders. Safety is ensured by:

Durable materials used in the tanks
Hydrogen sensors installed at critical points—typically near the electrolyzer and compressor

There are also alternative technologies that can store hydrogen in solid or liquid forms.

How does the complete system work?
A simple and schematic explanation:

The sun provides electricity to the photovoltaic modul
This electricity powers a PEM electrolyzer
The electrolyzer splits water into hydrogen and oxygen
Hydrogen is compressed and stored in tanks
When energy is needed, hydrogen powers a fuel cell
The fuel cell generates electricity for homes, vehicles, and industries, with zero emissions

Renewable Energy and Solar Systems

What Renewable Energy are
Renewable energy comes from sources that regenerate naturally and continuously. Unlike fossil fuels (like coal, oil, and gas), they do not run out and do not pollute. The main renewable sources are:

The sun (solar energy)
The wind (wind energy)
Water (hydropower)
Biomass
Earth’s heat (geothermal energy)

What a Photovoltaic System is
Given Italy’s geography, the sun is a highly abundant renewable resource from north to south. Therefore, solar energy is particularly important in our country. A photovoltaic system converts sunlight directly into electricity. This happens through solar panels made of silicon cells. When sunlight hits the cells, it creates direct current (DC), which is then converted into alternating current (alternating current – the kind used in homes) by an inverter. In summary:

Sunlight hits the panels
Panels produce electricity
Electricity powers lights, appliances, computers, and more

What a Solar Thermal System is
A solar thermal system, instead, is used to produce hot water (not electricity). It uses solar collectors that absorb the sun’s heat and transfer it to a fluid. This fluid then heats the water in a tank. It’s ideal for:

Bathrooms and showers
Heating indoor spaces
Swimming pools

How electricity is generated from the sun

Sunlight hits the photovoltaic panels
The cells convert light into electricity
The inverter makes the electricity compatible with household sockets

It’s a clean, silent, and emission-free process.

What happens to excess energy
When there is more sunlight than the house needs, the energy is not wasted. It is:

Immediately used (if needed)
Sent to the grid (through net metering)
Or stored in lithium batteries

Lithium batteries: what are they useful for?

They store solar energy during the day
They make it available at night or on cloudy days
They can power a home for several days, depending on capacity

What is a cogenerator?

Operation during daylight

During daylight hours in summer, the Elf-Tech system first stores the solar energy produced on the roof in batteries.
Excess solar energy is converted into hydrogen via electrolyzers and stored for winter.
Residual heat is collected in hot water tanks and it's available for use.
During summer nights, the user powers its home using the electricity stored in the batteries.

Operation at night and/or in winter

In winter, solar energy is never sufficient.
The Elf-Tech system’s seasonal hydrogen storage module ensures the electricity supply needed for users’ homes.
The system’s fuel cells convert the stored hydrogen into electricity.
In addition, the system can heat users’ homes and reduce or eliminate heating costs.

Water electrolysis and fuel cells: how hydrogen is produced and used

Introduction
Hydrogen is considered a key pillar in the energy transition toward a sustainable future. It can be produced from renewable sources and used to generate energy with zero emissions. Two core technologies in this process are water electrolysis and fuel cells. Below is a clear and detailed explanation of how they work, the available technologies, and their role in the modern energy system.

1. Water electrolysis: generating hydrogen with solar energy
Electrolysis is a chemical process that uses electricity to split water (H₂O) into its basic elements: hydrogen (H₂) and oxygen (O₂). When the electricity comes from renewable sources like solar power, the hydrogen produced is called green hydrogen. The process takes place inside a device called an 'electrolyzer'. There are different types of electrolyzers, each one with specific features.

1.1 Alkaline Electrolyzers (AWE – Alkaline Water Electrolysis)
These are the most technologically well-established. They use an alkaline solution (typically potassium hydroxide, KOH) as the electrolyte. They are reliable and affordable but have slower response times and are best suited for constant loads.

1.2 Proton Exchange Membrane Electrolyzers (PEM)
PEM electrolyzers are more compact and respond quickly to load variations. They use a solid polymer membrane as the electrolyte. They are ideal for variable renewable sources (like solar power),but they are more expensive due to the use of noble materials (e.g. platinum).

1.3 Solid Oxide Electrolyzers (SOEC – Solid Oxide Electrolysis Cell)
These operate at high temperatures (700–1000°C), using ceramic oxides as the electrolyte. They offer very high theoretical efficiency, especially when integrated into industrial processes where heat is available. They are still under development.

1.4 Anion Exchange Membrane Electrolyzers (AEM)
An emerging technology that tries to combine the benefits of alkaline systems (low cost) and PEM systems (fast response), using membranes that transport anions instead of protons. It's still in the testing and optimization phase.

2. Fuel Cells: Converting Hydrogen into Electricity
A fuel cell is an electrochemical device that converts the chemical energy of hydrogen into electrical energy. This process takes place by combining hydrogen and oxygen in a controlled manner, generating electricity, heat and water as the only byproduct.

2.1 How does a fuel cell work?
Inside the cell:

Hydrogen (H₂) enters the anode, where it is splitted into protons (H⁺) and electrons (e⁻)
Protons pass through the electrolyte membrane to the cathode
Electrons travel through an external circuit, generating electric current
At the cathode, protons, electrons, and oxygen (O₂) recombine to form water (H₂O)

2.2 Types of Fuel Cells
Fuel cells also differ based on the technology used. The main types are:

PEMFC (Proton Exchange Membrane Fuel Cell): the most widespread, used in vehicles and residential applications
SOFC (Solid Oxide Fuel Cell): operate at high temperatures, suitable for stationary applications
PAFC (Phosphoric Acid Fuel Cell): use phosphoric acid as electrolyte, for stationary use
MCFC (Molten Carbonate Fuel Cell): high-temperature cells used in industrial plants
AFC (Alkaline Fuel Cell): one of the earliest technologies, also used in space missions, but sensitive to CO₂

3. Electrolysis vs Fuel Cells
The full hydrogen production and use cycle includes:

Hydrogen production (via electrolysis)
Storage and transport (e.g. in cylinders)
Electricity generation (via fuel cells)

There are efficiency losses in both phases, but the flexibility and sustainability of the system make hydrogen a valuable energy resource for the future.

Conclusion
Hydrogen, produced through electrolysis and used in fuel cells, represents a concrete solution for clean and safe energy. Today, the technologies available are various and continuously evolving, with room for improvement in cost, efficiency, and scalability. Integrating these systems with renewable sources like solar energy enables a zero-emission virtuous cycle. To tackle global climate challenges, large-scale adoption of these technologies has become essential today.

Hydrogen: strategic storage for renewable energy

Hydrogen: the missing link for continuous and self-sufficient renewable energy
Renewable sources like the sun and wind are clean, abundant, and freely available—but they have one key limitation: intermittency. The sun doesn’t shine at night, and the wind doesn’t always blow. For this reason, even homes and communities powered by solar or wind energy need reliable energy storage systems.

Why is hydrogen the missing link?
Hydrogen, produced in excess when solar or wind energy is abundant, can be stored for days, weeks, or even months. This makes it the perfect complement to renewable energy. Unlike traditional batteries, which discharge quickly and are designed for short-term daily use, hydrogen can be stored long-term without losing its energy capacity.

Seasonal Storage: summer energy for winter use
During the summer months, solar energy production is very high—often exceeding daily consumption. A system equipped with an electrolyzer (which converts electricity into hydrogen) can generate hydrogen during summer, when energy is abundant and low-cost. This hydrogen can be stored in safe tanks and used in winter or during long cloudy periods, when renewable production is low.

A self-sufficient home thanks to hydrogen
By installing an integrated system with:

Photovoltaic panels
PEM electrolyzer
Hydrogen storage tank
Fuel cell

a home can become completely self-sufficient, producing, storing, and consuming energy all year round.

Hydrogen is safe even in large quantities
Contrary to common belief, hydrogen is very safe when handled with modern technologies:

High-pressure tanks are built with highly resistant, thoroughly tested materials
Systems are equipped with smart sensors that detect any leaks and intervene immediately
European and international regulations ensure very high safety standards

It’s also worth noting that hydrogen is non-toxic, lighter than air, and disperses quickly in case of a leak—reducing risk.

A Home or Neighborhood Network
Hydrogen production and storage aren’t just for a single home. Neighborhoods, apartment buildings, or small villages can share a centralized system to:

generate hydrogen from shared solar panels
store it safely in one location
use it for electricity and heating during cold months

This solution enables smart, scalable, cooperative energy management.

Conclusion: hydrogen provides continuity and energy freedom
Hydrogen lets us break free from fossil fuel dependence, ensuring:

uninterrupted energy even in winter or bad weather
security of supply
the possibility of living off-grid (without connection to the grid)
true energy independence, even at a collective scale

When integrated with a renewable energy system, hydrogen becomes the bridge between today’s energy and tomorrow’s, finally making unconditional, stable, and complete use of renewables a reality.

Energy freedom and energy democracy: a strategic link

What is energy freedom?
Energy freedom is the ability of an individual, family, or community to produce, manage, and consume energy independently of large centralized grids or fossil fuels. This is possible by accessible renewable technologies such as:

solar panels
storage batteries
hydrogen production and storage systems

It is a form of concrete autonomy, which allows you to protect yourself from increases in market prices, network interruptions, geopolitical crises related to fossil sources.

Energy Democracy: definition and values
Energy democracy is a broader concept that affirms everyone should have the right and opportunity to actively participate in energy production and control. Not just consumers, but also producers, decision-makers, and co-managers. This means:

equitable access to clean energy
community involvement in energy decisions
cooperative and shared models (e.g. energy communities)
decentralization of infrastructure

How do they connect?
Energy freedom is the tool while energy democracy is the goal. When a citizen or community has the technologies to produce energy (like solar + hydrogen), it becomes free. But when these technologies are widespread, shared, and collectively managed, energy democracy is born. In this scenario:

Energy is no longer a privilege or monopoly
Decisions are no longer imposed from above
Every citizen can be an active part of the change

A concrete example
Imagine a village or neighborhood where:

every roof has solar panels,
energy is stored (even as hydrogen),
residents decide together how to manage the systems,
profits from excess energy return to the community.

This is energy freedom + energy democracy: a fairer, autonomous, resilient society.