Fuel Cell Technology

Fuel cells are a type of technology that use hydrogen to produce useful energy. In fuel cells, electrolysis is reversed by combining hydrogen and oxygen through an electrochemical process, which produces electricity, heat, and water.

Fuel cells are electrochemical devices that convert the energy of a chemical reaction directly into electricity and heat. They are of great interest because they do not rely on the laws of thermodynamics for their operation so, in future, it will be possible to turn fuels into electricity with much higher efficiencies that can ever be possible with more conventional technology. The U.S. space program has used fuel cells to power spacecraft for decades. Fuel cells capable of powering automobiles and buses have been and are being developed.

Several companies are developing fuel cells for stationary power generation. Most major automobile manufacturers are developing fuel cell powered automobiles. There are five types of fuel cell (classified according to electrolyte) at different stages of development and with different potential applications.

The use of fuel cells for centralized electricity generation is unlikely within the next ten years, although by 2015 Europe, Japan and the USA could all have significant installed capacity. This market looks particularly promising in Japan where power generation costs are high.

Fuel cells, particularly high temperature fuel cells, are potentially well suited to the distributed power generation and CHP markets, both of which are growing. However, their market share will depend on long-term performance and cost-competitiveness.

Drawbacks of Carbon-based Fuel

To appreciate the various benefits of hydrogen as an energy carrier, it is important to understand the shortcomings of fuels we depend upon today. Conventional petroleum-based fuels like gasoline or diesel, as well as natural gas and coal, all contain carbon.

When these fuels are burned, their carbon recombines with oxygen from the air to form carbon dioxide (CO2), the primary greenhouse gas that causes global warming.

Furthermore, combustion of fossil fuels at the high temperatures and pressures reached inside an internal combustion (IC) engine (what powers most vehicles) or in an electric power plant produces other toxic emissions. Carbon monoxide (a poison, oxides of nitrogen and sulfur (NOx and SOx), volatile organic chemicals, and fine particulates are all components of air pollution attributable to the refining and combustion of fossil fuels.

When released into the atmosphere, many of these compounds cause acid rain or react with sunlight to create ground-level smog. Vast ecosystem damage, increased lung disease and cancer are the ultimate price we pay for consuming these fossil fuels.

IC vs. Fuel Cell - Superior Efficiency

Modern industrial development relied upon the widespread exploitation of these carbon-rich fuels. Mined in abundance, they were burned with little regard for overall system efficiency. But the search for alternatives has exposed another major shortcoming of carbon-based fuels: their energy is difficult to capture.

Harnessing explosions—the process by which an internal combustion (IC) engine converts chemical energy into mechanical energy—is inherently inefficient. Even after more than a century of refinement, most IC engines capture only 15–20% of the energy in gasoline. The rest of that energy is lost as waste heat and vibrational noise. Centralized electricity generation is similarly inefficient. The U.S.'s current electric system converts 33% of fuel energy into electricity and squanders most of the remaining heat.

Fuel cells produce electricity. Similar to a battery, a fuel cell converts energy produced by a chemical reaction directly into usable electric power. But unlike a battery, a fuel cell has an external fuel source—typically hydrogen gas—and will generate electricity as long as fuel is supplied, meaning that it never needs electrical recharging. Inside most fuel cells, hydrogen from a fuel tank and oxygen from the air combine to produce electricity and warm water. As a simple electrochemical device, a fuel cell does not actually burn fuel, allowing it to operate pollution-free. This also makes a fuel cell quiet, dependable, and very fuel-efficient.

In stark comparison, fuel cells running on pure hydrogen are dramatically more efficient. By harnessing the fuel's energy via a chemical reaction rather than combustion, a fuel cell can convert 40–65% of hydrogen's energy into electricity. While a hydrogen-burning IC engine pollutes less than one running on gasoline, its energy efficiency is still less than half that of a fuel cell.

Because a fuel cell's energy efficiency is not scale-dependent, stationary fuel cells can be sited locally where the waste heat can be used.

This cogeneration The production of electrical energy and another form of useful energy (such as heat or steam) through the sequential use of energy. of heat and power brings a fuel cell's energy efficiency close to 90%. All the while, this unparalleled energy efficiency arises from a reliable device that emits only drinkable water and scant traces of other emissions.

A fuel cell consists of two electrodes-a negative electrode (or anode) and a positive electrode (or cathode)-sandwiched around an electrolyte.

Hydrogen is fed to the anode, and oxygen is fed to the cathode.

Activated by a catalyst, hydrogen atoms separate into protons and electrons, which take different paths to the cathode.

The electrons go through an external circuit, creating a flow of electricity.

The protons migrate through the electrolyte to the cathode, where they reunite with oxygen and the electrons to produce water and heat.

Fuel Cell Technology

Drawbacks of Carbon-based Fuel

IC vs. Fuel Cell - Superior Efficiency

Further Fuel Cell Research Material - Books