BENEFITS OF FUEL CELLS
The environmental benefits of fuel cells are some of the main motivating forces in their development. These benefits include the zero- or near-zero-emission of criteria pollutants (NOx, SOx, CO, and hydrocarbons) and very low noise emissions. Environmentally friendly fuel cell properties could eliminate consumer contempt for power generation close to their houses and businesses. While most consumers probably would prefer to have conventional electricity generated at a location far from their homes due to the noise and pollution, the benign nature of fuel cells makes them non-offensive even if placed in residential communities. Depending upon fuel cell type and design, fuel-to-electricity efficiency ranges from 30 to 60 percent (LHV). For hybrid fuel cell/gas turbine systems, electrical conversion efficiencies are expected to achieve over 70 percent (LHV). When byproduct heat is utilized, the total energy efficiency of fuel cell systems approaches 85 percent.
As shown in Figure 3, stand-alone fuel cell systems have the capability of reaching efficiencies greater than 50 percent, even at relatively small sizes (e.g., 10 kW). Hence, fuel cell systems could reduce the impact of electricity production on global climate change by reducing the amount of greenhouse gases emitted into the atmosphere per kilowatt-hour of power. They would also reduce resource depletion and dependence on fossil fuels by allowing more power to be harnessed from an same amount of fuel.
Combined Heat and Power (CHP) or Combined Cooling, Heat and Power (CCHP) Capability
High-quality heat is available for co-generation, heating, and cooling. Fuel cell exhaust heat is suitable for use in residential, commercial, and industrial co-generation applications. The figure to the right compares conventional generation to CHP. On the left we see that the purchase of power from the grid must be supplemented with an onsite boiler to provide the same heating needs as what a fuel cellís waste stream (heat) could provide at no extra cost or investment.
The heat from a fuel cell can be used for a variety of purposes:
Fuel cells are assumed to be superior to the grid because they are on site and subject to fewer disruptions (e.g. storms knocking down wires). With no moving parts, fuel cells will have less instances of failure than mechanical systems.
Today, the long-term performance and reliability of many of the fuel cell systems has not been significantly demonstrated to the market. Research, development and demonstration of fuel cell systems that will enhance the endurance and reliability of fuel cells are currently underway. The specific RD&D issues in this category include: (1) endurance and longevity, (2) thermal cycling capability, (3) durability in installed environment (seismic, transportation effects, etc.), and (4) grid connection performance.
Fuel cell electrical output can be configured to be computer grade. For example, systems have been configured to provide 99.9999+ percent uptime. Furthermore, fuel cell power plants can be set up in a range of electrical outputs. Individual fuel cell systems also can be arranged in series to meet increasing load demands.
Permitting and licensing schedules are short due to the ease of siting. Furthermore, fuel cell power installations are exempt from air emission permitting requirements in many U.S. states and provide flexibility under many federal, state and local air pollution standards.
The fuel cell is inherently modular. It operates at near constant efficiency, independent of size and load. The fuel cell power plant can be configured in a wide range of electrical outputs, ranging from single kilowatt sizes up to multi-megawatt systems.
Distributed Generation (DG) refers to generation at or near the site of use (for example, at a near a building requiring power). Fuel cells are a form of DG, and can contribute to the establishment of a DG market because of their characteristics as described above. Instead of an electricity distribution infrastructure based on centralized power plants routing power through wires over long distances, fuel cells and DG make it attractive to spread small power plants throughout an electrical grid or a geographic area. The cluster