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Due to increasing awareness on the impact of fossil fuels on the environment, and heavier taxes on carbon emissions there is a worldwide effort to seek renewable sources of energy – alternative energy sources that increase energy efficiency and security.
A renewable source that’s gained significant attention in recent years is biogas, one of the most established renewable energy sources which is capable of producing heat, steam, electricity and vehicle fuel. [1]
Biogas: The Future of Renewable Energy
Many European countries have established policies to promote renewable energy, and this has resulted in a rise in biogas production over the past decade. For instance, the number of biogas plants in Europe increased from 16,834 to 17,376 in 2015 – an increase of 3% [2]. This has resulted in an increase in biogas output, with the amount of electricity produced from biogas estimated at 60.6 TWh; which corresponds to the annual consumption of 13.9 million European households. [2]
Biogas is produced using bacteria. Organic feedstock, such as food waste, manure and sewage, is broken down by bacteria using an anaerobic (oxygen free) process. This biogas is then processed and used as a source of energy. The main benefits associated with this energy (and other renewable sources) includes reducing greenhouse emissions and the environmental impact when compared to the use of fossil fuels.
The Challenge of Reliably Measuring Biogas Concentration
To effectively produce and use biogas as a source of renewable energy the ability to carry out accurate concentration measurements is crucial. This allows producers to analyse how much biogas is generated in each stage of production.
However, accurately measuring biogas is challenging due to variations in the concentrations of different gases in biogas. The composition of biogas varies depending upon the source. Biogas typically consists of 50%-75% methane (CH4) and 25%-50% carbon dioxide (CO2), while the rest is composed of water vapour (H2O), and traces of oxygen (O2), nitrogen (N2) and hydrogen sulphide (H2S). [3]
“low gas pressures can make most differential pressure devices unsuitable”
These wide ranges reflect how composition can change over time with changing conditions. And these compositional changes make biogas very difficult to measure confidently.
In addition to this low gas pressures can make most differential pressure devices unsuitable, and biogas is often dirty, with high moisture and particulate content. This can clog up measurement devices and introduce error into gas concentration measurements.
Inaccurate measurement is obviously problematic. Gas composition is directly related to the efficiency of turbines and fuel cells for generating electricity. Measuring the gas composition during production allows biogas producers to tweak the composition of the final product – ensuring that the gas produced is useful for efficient and clean energy generation.
The Ideal Device for Biogas Concentration Measurement
The solution to these challenges is obvious: accurately measuring biogas composition with the right device. A gas measurement instrument of integrity is required which is capable of simultaneously measuring the concentrations of carbon monoxide, carbon dioxide and methane present to a high degree to accuracy.
This is important as before an increase in the number of biogas plants in Europe can be justified, improvements in the process efficiency, and the development of new technologies for biogas production are necessary.
To do this the best gas sensing technology, to manage and measure the compositional changes in biogas, must be developed.
The ideal measurement device should have real-time atmospheric pressure and temperature correction. It should also allow integration with a wide range of gas detection systems for highly accurate and reliable measurement of CO2, and CH4 concentrations. The flexibility to work with additional gas detection technologies is also important, as is a wide operating voltage range.
Finding an accurate sensor with these features helps facilities measure exact biogas concentrations. This in turn helps facilities improve their production efficiencies and revenue streams due to increased biogas and energy production.
The Gascard NG for Biogas Concentration Measurement
The demand for accurate gas sensing technology to measure the concentration of the different gases present in biogas continues to grow. This is because finding the ideal device to do this is critical for optimizing the results of biogas production.
The Gascard NG infrared gas sensor from Edinburgh Sensors is designed for ease of integration with a wide range of gas detection systems that require high quality, accurate and reliable measurement of CO2, and CH4 concentrations.
It includes real-time temperature and atmospheric pressure correction via on-board sensors, and has the flexibility to incorporate additional technologies such as flow sensors. It has onboard true RS232 communications along with the option of TCP/IP communications protocols.
Its features include:
- On-board barometric pressure correction in the range 800 mbar to 1150 mbar.
- Extensive temperature compensation.
- Minimum operating voltage 7 V and wide operating voltage range (7 V to 30 V).
- True RS232 communications for control and data logging. Optional on-board LAN support.
References
1. European Biogas Association,
http://european-biogas.eu/wp-content/uploads/files/2013/10/EBA-brochure-2011.pdf
2. BioEnergy Insight Magazine, “Biogas Sector is Growing Steadily in Europe, EBA Says in New Report”, 2017,
3. EBA’s BIOMETHANE Fact Sheet, European Biogas Association,
http://european-biogas.eu/wp-content/uploads/files/2013/10/eba_biomethane_factsheet.pdf
