02-03-2013, 10:20 AM
FUEL CELLS FOR POWER GENERATION
FUEL CELLS.pdf (Size: 1.18 MB / Downloads: 112)
INTRODUCTION
Fuel cells are commercially available today for power generation ranging
in sizes from under one kilowatt (kW) to scalable multi-megawatt (MW)
systems – suitable for applications ranging from residential and small
industrial backup power, to large industrial “base load” grid applications.
These systems have achieved billions of kilowatt hours (kWh) of successful
operation at customer sites worldwide. In selected markets fuel cell
systems are cheaper to own and operate on a life-cycle basis than
incumbent technologies. State incentives and a 30% federal tax credit
are also helping early adopters reduce the initial cost of fuel cell systems.
Fuel cell power systems are quiet, clean, highly efficient onsite electrical
generators that use an electro-chemical process – not combustion – to
convert fuel into electricity. In addition to providing electricity, they can
supply thermal energy for hot water and space heating, or absorption
cooling. Fuel cells have the potential to reduce facility energy service
costs by 20% to 40% over conventional power service.
HOW A FUEL CELL WORKS
Fuel cells use electro-chemical reactions,
rather than combustion (burning a fuel) to
produce electricity. The process is the reverse
of electrolysis. In electrolysis the action of
an electric current decomposes water into
hydrogen and oxygen, whereas in a simple fuel
cell the two gases can be combined electrochemically
to produce electricity, heat and
water. In practice, the process is more involved,
and each type of fuel cell has its characteristics,
operating temperature, materials, and flows.
What they have in common are high electrical
efficiency, no combustion in the basic reactions,
and a clean exhaust stream.
TYPES OF FUEL CELL SYSTEMS
The common types of fuel cells are phosphoric
acid, molten carbonate, solid polymer (or
proton exchange membrane) and solid oxide, all
named after their electrolyte. Because of their
different materials and operating temperatures,
they have unique characteristics, but all share
the potential for high electrical efficiency and
reduced emissions.
All fuel cells require H2 as a fuel, but some
fuel cells like molten carbonate (MCFC) and solid
oxide (SOFC) can also utilize carbon monoxide
(CO). Hydrogen may be acquired from any of
several gas distribution companies worldwide
or can be produced from hydrogen rich fuels
such as natural gas by a process called steam
reforming or auto thermal reforming. Use of
liquid fuels like diesel, gasoline, and other fossil
fuels is possible but more complicated because
of their high sulfur content and more complex
molecular structure.
The Ballard Mark1030 for Residential Coge ner ation
The Mark1030 was designed to provide
electricity; heat and hot water, as well as
environmental benefits for homeowners
currently experiencing high electricity costs in
comparison to gas costs. The product actually
satisfies two audiences, driving more business
and therefore increased revenue to gas
companies as well as providing an alternative
for homeowners to shift energy usage from
high priced electrical grids to lower cost energy
products for maximum savings.
Many App lications for the Power Markets
Distributed Energy Systems’ regenerative fuel cell technology can be used
in a wide range of applications including backup power for telecom and
other critical loads, peak shaving, and load leveling in premium power
markets and for remote applications. The technology has been used and
validated with renewable sources of energy such as wind and solar.
Distributed Energy Systems’ hydrogen technology group is actively
developing and demonstrating capability in domestic and global wireline
and wireless telecom backup power applications.
Other markets for our technology include UPS markets based upon our
regenerative fuel cell technology, Generator Set markets – our systems
offer storage flexibility – and backup power for utility substations and
cable television markets.