26-04-2014, 11:26 AM
Renewable Hydrogen Production Using Electrolysis
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INTRODUCTION
Hydrogen provides a promising method to help the U.S. achieve energy independence, make
strides in environmental stewardship, and develop a thriving economy. Hydrogen produced
through renewable energy sources, most commonly with a device which uses electricity to
separate water into hydrogen and oxygen called an electrolyzer, is an emissions-free way to carry
energy. Hydrogen is plentiful and can safely be harnessed for a variety of stationary and mobile
applications.
Introduction to Renewable Electricity
With the exception of hydroelectric power, less than 1% of the electricity generated in the U.S.
today is produced by renewable energy. The primary reason is cost. While hydropower is cost
competitive today but limited geographically, wind, geothermal, and ocean power are rapidly
becoming cost competitive with traditional electricity generation, and the cost of solar energy is
beginning to decrease as efficiency and manufacturability progress is made. Although biomass
can be burned to produce electricity and an emerging technology called microbial electrolysis cells
(electrohydrogenesis) has been shown to produce hydrogen biologically, these topics are covered
in other Fact Sheets of this series. Following are brief descriptions of the most common sources
of renewable electricity:
Wind Turbines
Wind turbines convert wind energy into electricity. Wind power is the
fastest growing electricity source in the world, and utilities throughout
the U.S. are installing wind farms (see photo) for additional power
generation. Large turbines can be up to 180 meters tall and produce 1.5
to 5 megawatts of power. (By comparison, the average household light
bulb requires 60-100 watts). Small turbines are also available to provide
power for homes or remote locations. Wind turbines can be sited and
installed faster than many conventional power plants, and technology
advancements are making it possible to generate electricity from low
wind speeds. Also, despite a common misperception about turbines’
impact on avian populations, they account for a fraction of 1% of bird
fatalities caused by human influences (the two major contributors being
buildings and domestic cats)
Hydropower
Hydropower captures the energy of fl owing water to produce
electricity, and is the most widely-used renewable energy
technology. There are a variety of hydropower technologies,
but the most common is impoundment hydropower, which
uses a dam to store and release water. This technology does
have an impact on the local environment. Other, lower impact
hydropower technologies are in use, but they generally provide
electricity on a smaller scale.
Hydrogen Production through Electrolysis
The main commercial advantages of hydrogen production by electrolysis are its scalability and the
emission-free production of hydrogen (when produced via renewable energy). Conventional
electrolysis is the most common method used to produce renewable hydrogen. Electrolysis
involves the separation of water into hydrogen and oxygen, using an electric current. Although
some electrolyzers use chemicals or intense heat to help the separation, conventional electrolysis
uses no chemicals, and works at room temperature.
Renewable Energy for a Hydrogen Future
In the near term, hydrogen produced in the U.S. may be from fossil fuels, but industry and
governments have their sights on increasing hydrogen production from renewables. Hydrogen
can help renewable electricity technologies mature and become more cost-competitive. In the
meantime, hydrogen production from fossil fuels can use low cost, existing infrastructure along
with emerging methods to capture and store greenhouse gas emissions to provide hydrogen while
minimizing environmental impact.
Renewables are an emissions-free way to produce hydrogen by electrolysis, and, conversely,
hydrogen offers a way for renewables to generate transportation fuel and reliable power. The
versatility of renewable technologies allows them to be adapted to meet diverse energy needs.
Though costs for some renewable technologies are higher than traditional generation sources,
technology advancements and increased market penetration are reducing prices. Additionally, the
environmental benefits help to compensate for the higher costs. When taken as a whole, the
future conjunction of hydrogen and renewable energy technology is a promising one.