Many MAN gas engines already include an optional H2-ready option that enables them to function with up to 25 percent hydrogen content, but their development poses unique challenges. Matthias Auer from MAN Energy Solutions discusses them here.
Hydrogen is a highly flammable gas and must be stored in tanks that have undergone rigorous crash tests to protect both itself and those around it. Such tanks typically feature special absorbent materials which absorb excess hydrogen like sponges.
1. Fuel Cells
Hydrogen fuel cells convert chemical energy to electricity without emitting harmful greenhouse gas emissions, producing only water and heat as byproducts.
An anode catalyst ionizes hydrogen molecules, splitting their protons and electrons to form positive hydrogen ions and negative electrons that travel over to the cathode side for use with oxygen from outside air in producing electricity and water as outputs.
There are various types of fuel cells, each operating differently. Molten carbonate fuel cells (MCFCs), for instance, operate at higher temperatures than their counterparts and make an ideal fit for large stationary power generators. They use molten salt solution as an internal reforming catalyst in order to separate hydrogen from traditional fossil fuels like natural gas – this process is known as reforming.
2. Reverse Electrolysis
Hydrogen fuel cells utilize reverse electrolysis to convert hydrogen and oxygen into electricity, producing no greenhouse gas such as carbon dioxide but do produce some nitrogen oxide emissions.
Fuel cell vehicles utilize a membrane called a fuel cell membrane that separates hydrogen and oxygen much like how a sponge absorbs water. Hydrogen is supplied from one or more tanks built into the vehicle while oxygen enters via another side of the membrane.
This releases electrical energy into a flow that powers an electric motor that propels the car, or charges up a buffer battery that extends driving range or captures braking energy to extend storage capacity – giving FCEVs similar performance and feel to traditional vehicles while decreasing environmental impacts.
3. Fuel Storage
Hydrogen is an extremely safe fuel when handled appropriately, as it’s non-toxic, lightweight, and dissipates rapidly in an event of an accident.
Hydrogen should be stored either pressurised in a tank, or liquid form and chilled, to preserve energy loss when compressed or liquefied over distance transport. Storage systems must be well insulated and ventilated. Liquid hydrogen also loses energy during compression or liquefication processes that create long distance transportation costs.
Hydrogen can be produced near its point of use using renewable electricity and storage systems, or natural gas, thus decreasing dependence on fossil fuel suppliers and increasing access to energy. Furthermore, hydrogen-powered cars are safer and more enjoyable to drive than hybrids due to reduced engine noise and improved driving experience; similarly hydrogen powered aircraft and ships help eliminate many noxious chemicals from the air such as nitrogen oxides (NOx), which contribute to brown-orange haze over some cities.
4. Fuel Injectors
Hydrogen gas is a colorless form of energy often employed for industrial processes that involve pollution control. Additionally, hydrogen emissions from fossil fuel combustion can be stored away and reused as renewable energy carrier using special storage systems referred to as “green hydrogen.”
As opposed to electric vehicles with lithium-ion batteries that need external power sources for charging, hydrogen fuel cell vehicles use an efficient onboard power plant that converts pressurized hydrogen into electricity via water electrolysis using renewable resources such as solar or wind energy as power sources.
An anode fuel cell receives hydrogen and oxygen from separate tanks, while its cathode receives ions from an electrolyte solution. When electrons combine with ions at the cathode, electricity, heat, and pure water vapor are generated, which escape through an open tube under the vehicle.
5. Electrodes
As with their internal combustion engine counterparts, hydrogen fuel cell vehicles also produce electricity to power their electric drivetrains; this energy comes from both a small storage battery and their own fuel cell system.
Compressed hydrogen stored in a tank (using Sundyne PPI compressors) is fed into the anode side of a fuel cell while oxygen from air is pumped to its cathode side. At the anode side, a catalyst breaks up hydrogen molecules into protons and electrons; these electrons migrate to the cathode side where they combine with oxygen to produce water and electricity.
Water and heat are the only by-products of this reaction – no pollutants*. Energy used to split water molecules may come from fossil fuels or renewable sources like wind or solar power.
6. Spark Plugs
Spark plugs resemble J-shaped metal pieces with domes on either end and central electrodes, and when activated by an ignition coil they produce an electromotive force to create an electricity difference between their center and ground electrodes. When this spark ignites air and fuel in a combustion chamber it generates mechanical power that drives an engine’s crankshaft.
Hydrogen internal combustion engines use hydrogen and oxygen in their engines’ cylinders to generate electrical energy and water vapor instead of carbon dioxide, the main greenhouse gas produced by fossil fuels. They can be used to power cars, trucks, buses, as well as heavier machines like backhoe loaders.
Green hydrogen is created using renewable solar and wind energy and stored in tanks to be transported directly to vehicles for zero-emission driving, helping make zero-emissions driving possible across the economy.
7. Heat
Hydrogen is a high-performance fuel that emits no greenhouse gas emissions and only water vapor as exhaust. Due to its higher auto-ignition temperature, hydrogen engines can run with leaner air/fuel ratios than traditional combustion engines – further improving performance and efficiency.
This can make the engine more energy-efficient and extend its range, as well as decrease its reliance on fossil fuels, creating a more sustainable energy source.
Hydrogen for these engines is stored under pressure on board vehicles to allow for quick refueling, using tanks made of materials called Hydrides which absorb it like sponges absorb water, providing more storage with reduced volume – helping keep vehicle weight down while creating greater power.
