Fuel Cell Technology
What is a Fuel Cell?
Originally invented by Sir William Grove in 1839, fuel cells are now becoming a viable source of power. Fuel cells can in their simplest form be regarded as generators. But whereas conventional generators use internal combustion engines to rotate an alternator, fuel cells generate power by producing electrons directly, with no moving parts. As a result, they are very efficient and reliable. Moreover, they are almost silent and, other than electricity and heat, they produce only water vapour. This makes them ideal for indoor use.
Efficient and reliable.
Fuel cells have no moving parts so they are very efficient and reliable, requiring little maintenance.
Clean and quiet.
Fuel cell systems are clean, very quiet and produce no exhaust gases other than water vapour.
How does it work?
The EFOY fuel cell is the ideal power generator for your 12 V and 24 V battery. The integrated charge controller permanently monitors the charge level of your superstructure/on-board battery and recharges it fully automatically if necessary. It switches off again (standby mode) as soon as the battery is fully charged. This means that you always have full energy reserves and it protects your battery from damaging deep discharge through continuous charging. To operate 230 V consumers, such as coffee machines or hair dryers, you will also need an inverter.
The EFOY Power Generation Principle
EFOY fuel cells are based on DMFC (Direct Methanol Fuel Cell) technology. They convert chemical energy into electrical energy without interim stages and without much loss of efficiency. The methanol in the fuel cartridge is supplemented by oxygen from the air, and is used to produce electricity. In addition to power, all this creates is waste heat and water vapour with little carbon dioxide, making it efficient and exceptionally environmentally friendly.
The Principle of Water Recovery
The stack is the power-generating core of the EFOY fuel cell. It consists of individual cells, each of which is set up to include a cathode and a membrane. As an electrolyte, the membrane separates the anode and cathode from each other. Positively charged electrical particles, known as protons, can diffuse through the membrane. On the side of the anode, water and methanol are added, and on the side of the cathode, oxygen is taken from the ambient air. In the reaction at the anode, H+ ions and free electrons are created, as well as the reaction product carbon dioxide (CO2). The protons can cross the membrane. The electrons, however, have to travel to the cathode side via a connected electric circuit during which they generate power. On the cathode, the H+ ions, the oxygen from the air and the electrons are converted into water vapour
Fuel Cells Explained
The Cell
A fuel ‘cell’ essentially consists of two plates (the anode and cathode) separated by an ‘ion-conducting’ electrolyte which can come in many different forms.
Stage 1
A fuel (the simplest form being hydrogen) is passed across the anode where it is split by a catalytic reaction into hydrogen ions (H+) and electrons.
Stage 2
Simultaneously an oxygen source (usually either air or pure oxygen) is passed across the cathode side of the cell.
Stage 3
As the fuel cell’s electrolyte layer is designed only to allow a flow of hydrogen ions through it from anode to cathode, these flow across the membrane forcing the electrons to flow through an external electrical circuit to the cathode side where they then combine with the hydrogen ions and oxygen to form water.
This flow of electrons creates the electrical current or power from the fuel cell.
The Stack
Each individual fuel ‘cell’ produces only a small amount of power, each cell’s output differing dependent on their design and size.
To provide the higher levels of power output required from a fuel cell system for practical use as an energy source, the cells are then combined to form a fuel cell “stack” the size of which is dependent on its manufacture and requirements.
The systems available on the market today are more correctly termed as fuel cell systems as they comprise all the cells in a ‘stack’ plus the electronic controls required to meter the fuel and oxygen, and control the process.
Technologies
Fuel Cells offer a wide choice of power outputs dependent on the system chosen.
These vary from smaller portable fuel cells which produce low power outputs from 1W to 150W running on gaseous hydrogen or methanol, to standby power units from 10kW to 100kW running on hydrogen through to prime power 250kW+ units mainly fuelled by natural gas, with alternative sources of methane such as biogas now becoming available.
Today’s fuel cell development continues apace with new technologies appearing on a regular basis. In terms of those systems which could be deemed commercially available, there are several variants all of which can be chosen, dependent on the requirement of the user.
High Temperature Fuel Cells
These fuel cells have long start-up times and are generally higher power units from 200kW upwards. As such they are best suited to continuous use.
Even though fuel cells in general are considerably more fuel efficient than other forms of power production, use of the high-grade heat produced by these types of fuel cell for combined heat and power (CHP) or cooling via absorption chillers, can increase efficiency further by up to 85% in total.
Low Temperature Fuel Cells
These fuel cells have rapid start-up but produce little in the way of usable heat. They are generally of lower power output (up to 20kW) and are ideal for standby and low-power, long runtime, prime power applications.
Fuel cell technologies are continuing to develop, but whilst they share the fundamentals and the technology adopted within them, their differing power outputs make each one suitable for differing applications.