(151b) Electrochemical Conversion of Ammonia and Nitrogen for Sustainable Food-Energy-Water

Electrochemical Conversion of Ammonia and Nitrogen for
Sustainable Food-Energy-Water

Gerardine G. Botte

Center for Electrochemical Engineering Research

Department of Chemical and Biomolecular Engineering

Russ College of Engineering and Technology

Ohio University, Athens

OH 45701

The
production of reactive nitrogen fertilizer via the Haber-Bosch (HB) process,
combined with industrialization and intensification of agriculture, has created
an abundant global food supply to support population growth, but has doubled
the amount of reactive nitrogen compared to pre-industrial levels.¹
With those perspectives, ammonia can be seen as an important chemical of use or
as an environmental challenge. Ammonia emissions into air (ambient ammonia) and
water represent an environmental challenge. Ambient ammonia not only
contributes to inorganic PM2.5 (particulate matter with an aerodynamic
diameter of less than 2.5 μ m) directly but also plays an important role in
secondary organic aerosol formation by interacting with gaseous phase organic
acids and forming condensable salts. In addition, ammonia emissions in water
are associated with environmental problems such as algae bloom. Various
industries and other operations are considered ammonia emitters, but the ones
related to sustainable food production such as livestock management and
fertilizer application are among the major contributors accounting for 60-75%
of the ammonia emissions.^2-3

On the
other hand, ammonia produced commercially via the HB process is usually known
as one of the greatest inventions of the 20th Century. The HB process made it
possible for the first time to produce synthetic fertilizers and produce
sufficient food for the Earth’s growing population. However, the HB process requires
high temperatures and pressures and as a result it can only be done in large
plants which consume large amounts of power and generate large quantities of CO₂
from the fuels used to power the process, such as natural gas. It is estimated
that the HB process accounts for nearly 1% of the entire global power
consumption. Due to the sheer scale of the HB process, distribution from the
point of production to the point of use becomes an additional carbon and energy
burden. Alternative methods of manufacturing ammonia that enable small scale,
distributed generation at the point of use using renewable energy and
sustainable feedstocks could have a great impact on global CO₂
emissions.

A
closed loop approach that includes producing fertilizer at the point of use,
applying nitrogen fertilizer as close to the time that crops needs it, and
recovering and recycling nitrogen fertilizer can contribute to address the
challenges related to ammonia emissions, while decreasing water and energy
consumption. Electrochemical conversion of nitrogen and ammonia presents an excellent
platform to achieve this closed loop approach. Dr. Botte and members of her
research group at the Center for Electrochemical Engineering Research (CEER)
are working on the electrochemical conversion⁴/synthesis of ammonia⁵
in alkaline media. In this talk, recent advances in the platform process for
ammonia and nitrogen removal/recycling and ammonia synthesis will be discussed
as well as their application for sustainable food, energy, and water.

References:

1.    
Grand Challenges - Manage the
Nitrogen Cycle [WWW Document], n.d. URL
http://www.engineeringchallenges.org/9132.aspx (accessed 5.28.18).

2.    
G. E. Mansell, "An Improved
Ammonia Inventory for the WRAP Domain (Final Report)", ENVIRON
International Corporation, Report No. 415.899.0700, March 7 (2005).

3.    
FAO. Global estimates of gaseous
emissions of NH₃, NO, and N₂O from agricultural land,
International Fertilizer, Industry Association. Rome. 2001.

4.     Botte, G. G., Cooper, M. and Vitse,
F., (2009) Electro-catalysts for the oxidation of ammonia in alkaline
Media, U.S. Patent No. 7,485,211.

5.    
B. L. Sheets, G. G. Botte,
Electrochemical nitrogen reduction to ammonia under mild conditions enabled by
a polymer gel electrolyte, Chemical Communications 54 (2018), 4250-4253.