Grid independent power

As mentioned, the primary motivation for the PEFC development was the anticipated applicability in transportation. However, the economics of stationary use are more forgiving, and commercialization of the technology will likely begin as grid-independent power supphes. Figure 24-51 shows a 5-kW PEFC system operating on natural gas. 

Grid independent power 1-5 kW E.g. small Uninterruptible power supply, UPS, small remote stationary systems (energy supply for signaling or weather stations) Generator driven by ICE Lead acid battery Noise, Emissions... 

Every continent on the planet is surrounded by a cleaner, safer, more efficient energy resource. As conventional energy supplies are depleted, means are being developed, and in some cases are in actual operation, to convert the energy found in waves, tidal currents, ocean and river currents, ocean thermal gradients, and offshore wind into usable electric power for utility-scale grids, independent power producers, and the public sector. 

Cogeneration equipment must be safely connected to the utility grid. Utilities have objected to independent power generation by arguing that safety hazards can exist for their workers if independent systems continue to operate during system-wide blackouts. Such problems can be avoided by the installation of appropriate, standard safety equipment at the cogeneration site. 

Fuel cells will often be used in combined heat and power (CHP) systems in both homes and businesses. In these systems the fuel ceU wiU need to connect to the AC mains grid. The output may also be converted to AC in some grid-independent systems. 

Control equipment and user interface for remote load control, reactive power control and grid-independent operation. 

If grid-independent operation is required, a more complicated control system is necessary. A frequency control must be added. The inverter has to be able to supply as well as to demand reactive power. Especially when an asynchronous generator (the most common type of generator) is used in a hybrid system, the inverter must supply reactive power for grid-independent operation. 

A fuel cell power system may be sized to generate any power between minimum and maximum load power. Obviously, if it is sized at a lower end of this range it would work with a very high capacity factor, but it would cover only a portion of the power needs. The rest would have to be supplied from the grid. If it is sized to cover all the power needs it would provide grid independence, but it would operate with a very low-capacity factor. 

The term "portable power system" is not sharply defined. Hoogers (34] attempted to define it as "a small grid-independent electric power unit ranging from a few watts to roughly one kilowatt, which serves mainly a purpose of convenience rather than being a primarily a result of environ-... 

A load ramp rate of 80 kW/second when operated independently of the utility grid and following the initial ramp up to full power... 

Hydropower provides an essential contribution to the national power grid its capability to respond in seconds to large and rapidly varying loads, which other baseload plants with steam systems powered by combustion or nuclear processes cannot accommodate. Also, ownership is spread over a broad base. The owners comprise federal and state agencies, cities, metropolitan water districts, irrigation companies, and public and independent utilities. Individual persons also own small plants at remote sites for their own eneigy needs and for sale to utilities... 

---