Gasless or Going for Green Gas? The Positive Characteristics of Biogas
Within three decades, it is intended that almost the entire energy supply in countries such as the Netherlands will be sustainable. No fossil fuels. No natural gas. Gasless. Gasless? To achieve an efficient and feasible energy transition, gas does seem to be necessary. Sustainable gas. The positive characteristics of this energy source in a nutshell. – written by Sjaak Klein Gunnewiek, Sales manager biogas projects at HoSt Bioenergy Systems
Biogas is a source of energy, which does not require any conversion to obtain the energy, and therefore has a high yield. Hydrogen, for example, is an energy carrier; it is produced by conversion (with conversion loss) of natural gas or electricity (the energy source).
Currently over 90% of hydrogen is produced by steam reforming: with an efficiency of about 75%, hydrogen and carbon dioxide are produced from natural gas and water. This is called grey hydrogen due to the use of fossil natural gas.
More and more initiatives are being developed to produce green hydrogen. Electrolysis is a technique that uses electricity to produce hydrogen with an efficiency of around 75%. In the long term (>10 years) this route offers many opportunities. For example, for storing or transporting local surplus of electricity production. The conversion of electricity from large solar parks into hydrogen for use on another continent is an example of this. In terms of application in the future, hydrogen will, in my opinion, be particularly interesting for the industry (see below in this blog).
Biogas is produced through anaerobic digestion from inexhaustible organic waste streams. These waste streams are available in abundance regionally. These include manure, organic waste, waste from the food industry, sludge from water purification and agricultural waste.
If we take the Netherlands as an example, we can see that no less than 1.5 billion Nm3 (cubic metres) of biomethane can be produced from all the available manure in this country. With an average annual gas consumption of 1,350 Nm3, this results in more than 1 million warm Dutch homes!
Biogas is a sustainable energy source for various flexible applications:
- Biomethane production from biogas. Biogas has a low methane content (50-65%). Thanks to biogas upgrading, with membrane technology for example, it is upgraded to the right quality with the same properties as natural gas. Any desired gas quality and calorific value is possible and can be fed into both the low- and high-pressure natural gas grid.
- Bio-CNG or bio-LNG from biogas. Both bio-CNG and bio-LNG are a sustainable fuel for vehicles. Bio-CNG production is also ideal if there is no gas infrastructure at the biogas production site. HoSt has already supplied several of these ‘virtual pipeline’ systems in the US. The production of bio-LNG is slightly more complex, but bio-LNG has about 3 times the energy content of bio-CNG;
- In a combined heat and power (CHP) plant, biogas can be converted into heat and green electricity;
- Direct use in the industry, by combusting biogas in the biogas boilers for process heating.
One of the main advantages of biogas is its year-round production. Solar and wind energy have limited full load hours, which causes peak loads on the grid and requires smart storage methods for the future. The gas network acts as a buffer when the demand for gas is lower. As a result, no cubic metres of gas are wasted, and biogas can play an important role in balancing the energy supply.
As HoSt is founded in The Netherlands, this is the location where HoSt does most of its research. The Netherlands is the most densely populated country in the European Union (EU). The local gas infrastructure has an exceptionally good national coverage. And a central heating boiler that can run on biomethane without any modifications is present in almost all local homes and buildings. The gas network can also be used to transport hydrogen, although this will require modifications because hydrogen can easily escape from valves because it is a light gas. Biomethane has an energy density three times as high (approximately 9 kWh/Nm3) as hydrogen and no network modifications are necessary. These methods can also be used in countries with a similar infrastructure.
Millions of homes are difficult to get off the natural gas (affordably) because low-temperature heating, which is necessary for electric heating with a heat pump, is not feasible. It is for a good reason that between 40% and 60% of our energy is still expected to come from gaseous energy carriers in 2050.
To achieve the sustainable energy ambitions, a combination of a gasless construction, adapting existing homes to heating with heat pumps and biomethane for the old homes is necessary.
My expectation is that most of the transport will ultimately be electric. Biomethane will gain a share in the energy mix for transport by means of CNG and LNG, which is particularly interesting for heavy duty transport (ships/trucks). Except for heavy-duty transport, hydrogen is not interesting for mobility as too much energy (about 40%) is lost both in production (about 20-30%) and in the fuel cell. Incidentally, CNG and LNG also involve a loss of efficiency in the combustion engine.
National governments are already stimulating the energy transition, as well as CO2 emission reduction techniques. Green gas production from sustainable low-value regional biofuels provides an emission reduction of no less than 90% compared to the use of natural gas. In addition, fermentation in combination with green gas production results in an extra reduction of emissions; after all, the emissions from the residual flows are reduced. For example, manure fermentation reduces nitrogen and methane emissions by about 40% and 60% respectively. The methane is put to good use in the production of biogas, instead of being released into the atmosphere. Two birds with one stone.
Biogas production is a readily available clean technology and biomethane is necessary for a realistic energy transition. Commitment to a combination of gas-free new-builds, conversion of existing buildings to heating with heat pumps and biomethane for old homes seems the right route. Time to step on the (green) gas!