Hydrogen production from gasification of agricultural waste

1. • Hydrogen can be used in fuel cells to generate power using a chemical
reaction rather than combustion, producing only water and heat as
byproducts. It can be used in cars, in houses, for portable power, and
in many more applications.
• Different Types of Hydrogen, based on Production Method
• The crux of emissions from this method, however, lies in the method
in which the electricity is produced.Hydrogen is often associated with
a color, whether it’s grey, blue, or green. These colors represent key
distinctions in the emissions profiles for the various ways hydrogen is
produced:

2. • Grey Hydrogen:
• Grey hydrogen is typically produced from natural gas in a process called methane reformation while brown hydrogen is produced
from coal gasification.
• These are the most dominant and cheap method of hydrogen production, but account for the “highest CO2 emissions”.
• Blue Hydrogen:
• Blue hydrogen is usually produced using fossil fuels but is usually dealt with by using CCS(Carbon Capture Storage).
• Blue hydrogen can be a stepping stone of sorts to move away form ‘Grey and Brown Hydrogen and move towards a green
hydrogen economy.
• Green Hydrogen:
• Green hydrogen is produced using renewable sources such as solar and wind via electrolysis of water.
• The process is clean but currently expensive. But the costs of renewable energy sources have plummeted in recent years, Solar PV
in particular
• The costs associated with this are a function of electrolyser costs and cost of energy source.
• As of today, only 4% of Hydrogen produced is through electrolysis (Green Hydrogen).

4. Green Hydrogen & Production Methods
There are different Green Hydrogen Production
methods as elaborated in the figure below.

5. Direct Water Splitting:
In this process, solar radiation is directly used to split water into hydrogen and oxygen molecules. This process is
also known as Photoelectrochemical (PEC) water splitting.
The PEC water-splitting process uses semiconductor materials to convert solar energy directly to chemical energy
in the form of hydrogen.
The semiconductor materials used in the PEC process are similar to those used in photovoltaic solar
electricity generation, but for PEC applications the semiconductor is immersed in a water-based
electrolyte, where sunlight energizes the water-splitting process.

6. Biomass Gasification:
Biomass gasification is a technology pathway that uses a controlled process involving heat, steam, and oxygen to convert
biomass to hydrogen and other products, without combustion.
Because growing biomass removes carbon dioxide from the atmosphere, the net carbon emissions of this method can be low,
especially if coupled with carbon capture, utilization, and storage in the long term.
Gasification is a process that converts organic or fossil-based carbonaceous materials at high temperatures (>700°C), without
combustion, with a controlled amount of oxygen and/or steam into carbon monoxide, hydrogen, and carbon dioxide.
The carbon monoxide then reacts with water to form carbon dioxide and more hydrogen via a water-gas shift reaction.
Adsorbers or special membranes can separate the hydrogen from this gas stream.

7. Electrolysis:
Technology for grid-scale hydrogen energy storage is a regenerative fuel cell. A regenerative hydrogen fuel cell system consists of a water
electrolyzer, compressed hydrogen gas storage tanks, and a fuel cell.
The system uses electricity to generate hydrogen from water in an electrolyzer. The hydrogen is stored in high-pressure tanks and dispatched to
the hydrogen fuel cell to generate electricity when desired.
Energy in the form of electricity is used in an ‘Electrolyser’ which splits water into hydrogen and oxygen. Hydrogen is under pressure in storage
tanks. The oxygen to is stored as it is required in the fuel cell process to electricity again. It is important to note that hydrogen is not an energy
source, but is an energy carrier.
Regenerative Hydrogen Fuel Cells offer an environmentally friendly method to store excess power from solar panels and wind turbines. The fuel
cells convert excess electricity from the solar panels and wind turbines into hydrogen that is stored on-site.

8. • Hydrogen Production from Biomass Gasification
• Abstract
• Upgrading of gas streams formed from biomass gasification for the
production of pure hydrogen or hydrogen-rich gases is facing many
technical and technological challenges. Both gasification and hydrogen
separation technologies play a significant role in the total efficiency of the
production process. The aim of this chapter is to analyze gasification
processes and examine the possible options for hydrogen production from
the product gas streams from a gasification process. Gas conditioning and
hydrogen purity will be taken into consideration as well as economic
aspects of the integrated process.

9. Biomass gasification technology: The state of
the art overview
• Abstract
• In the last decades the interest in the biomass gasification process has
increased due to the growing attention to the use of sustainable energy.
Biomass is a renewable energy source and represents a valid alternative to
fossil fuels. Gasification is the thermochemical conversion of an organic
material into a valuable gaseous product, called syngas, and a solid
product, called char. The biomass gasification represents an efficient
process for the production of power and heat and the production of
hydrogen and second-generation biofuels. This paper deals with the state
of the art biomass gasification technologies, evaluating advantages and
disadvantages, the potential use of the syngas and the application of the
biomass gasification. Syngas cleaning though fundamental to evaluate any
gasification technology is not included in this paper since; in the authors’
opinion, a dedicated review is necessary.

11. • Nowadays renewable energy sources are an essential issue in the
framework of global energetic scenario. Biomass can represent an
effective substitute to conventional fuels and a sustainable, carbon-
neutral and environmental-friendly energy resource. Biomass
gasification is a promising technique in order to valorize biomass
conversion in energy, biofuels and chemicals.