Different technologies for high efficiency
Fuel cells, like batteries, generate electricity from an electrochemical reaction. Batteries have a self-contained energy supply and must be discarded (primary batteries) or recharged (by an external electricity source) when that supply runs out.
For their part, FCs use external sources of chemical energy, in the form of fuel such as hydrogen or hydrocarbons (natural gas or methanol), from which hydrogen is extracted. As a result FCs can run as long as their supply of fuel (and oxygen) is uninterrupted.
Like primary and secondary batteries that come in different chemistries (e.g. carbon zinc, lead-acid, nickel cadmium, nickel-metal hydride, lithium ion, etc.) FCs come in varying technology types that use different electrolytes, anodes and cathodes made of diverse materials.
These types include: proton exchange membrane fuel cells (PEMFCs), direct methanol fuel cells (DMFCs), solid oxide fuel cells (SOFCs), alkaline fuel cells (AFCs), molten carbonate fuel cells (MCFCs) and phosphoric acid fuel cells (PAFCs).
Converting chemical energy into electricity and heat using FCs is much more efficient than burning fossil fuels in thermal power plants or in internal combustion engines.
FCs produce heat as a by-product of the electrotechnical reaction (from under 100°C for AFCs and PEMFCs up to around 1 000°C for SOFCs). In FCs operating at high temperatures, process heat can be used in combined heat and power (CHP) and combined cooling and power (CCP) plants. When heat is captured for such cogeneration, the efficiency of FCs can be increased significantly, from around 60% to over 80% in some processes.
Fuel cell types can vary from tiny devices producing only a few watts of electricity, used to charge or power consumer electronic products, to portable systems like auxiliary power units (APUs) for residential or mobile use or for road vehicles or aircraft (for ground and in-flight power generation), right up to power generation installations.
A fast expanding use of FCs is observed in transportation, mainly to power (or give additional power to) large public transport or industrial electric vehicles (EVs) like buses or forklifts. These EVs often benefit from easy access to hydrogen fuelling installations at their home base.
On the other hand, hydrogen fuelling and infrastructure support for private EVs are not yet widely available in most countries, limiting the adoption of such vehicles.
Additionally, all FC technologies have been tested for ship propulsion, with some found to present interesting prospects.
FCs for stationary applications will represent the lion’s share of the global value of FC applications in the future, in particular when used in reverse mode to meet power storage and power generation needs (see article in e-tech, March 2016). As noted in the article: “FCs for stationary applications should be able to use any locally available fuel”.
Using renewable sources to produce the hydrogen needed by FCs by electrolysis that splits water into hydrogen (which can be converted back into electricity in FCs) and oxygen is a perfectly clean solution which generates electricity without any harmful emission and can even provide a storage solution when using reverse mode.
The US Office of Energy Efficiency & Renewable Energy indicates that “electrolyzers can range in size from small, appliance-size equipment that is well-suited for small-scale distributed hydrogen production to large-scale, central production facilities that could be tied directly to renewable or other non-greenhouse gas-emitting forms of electricity production”.
IEC TC 105 work to underpin future of FC technologies
The wide range of FC technologies and of their applications dictates a need for common International Standards. These are prepared by IEC TC 105: Fuel cell technologies, which first met in 2000.
Its scope is “to prepare international standards regarding FC technologies for all FCs and various associated applications, such as stationary FC power systems, FCs for transportation such as propulsion systems, range extenders, auxiliary power units, portable FC power systems, micro FC power systems, reverse operating FC power systems, and general electrochemical flow systems and processes”.
To carry out its tasks, TC 105 set up 14 Working Groups (WGs). It also works in two Joint Working Groups: JWG 16: Cogeneration Combined Heat and Power (CHP), managed by IEC TC 5: Steam turbines, and JWG 7: Flow Battery Systems for Stationary applications, managed by IEC TC 21: Secondary cells and batteries.
Over 70 experts from 11 member organizations are currently active in this TC, which had issued 19 publications as of April 2017 and is preparing many more.
IEC TC 105 refers to Standards developed by more than two dozen IEC TCs, as well as by nine International Organization for Standardization (ISO) TCs, such as ISO/TC 11: Boilers and pressure vessels, ISO/TC 110: Industrial trucks and ISO/TC 197: Hydrogen technologies.
The FC global market is fast expanding, at a compound annual growth rate (CAGR) expected to exceed 24% between 2016 and 2024. It is forecast to reach USD 25,5 billion, with stationary systems making up nearly two thirds of the total, according to a July 2016 Global Market Insights report.
This robust growth points to a heavy workload for IEC TC 105 in coming years.