Waste used for transportation
It is undeniable that we are facing a mobility paradigm shift. The fuel model based in technical and economic monopoly of fossil resources ─above all diesel and gasoline─ seems to be ending and alternatives based in renewable sources show up continuously. These technologies are more efficient and cause less damage to the environment.
Electric cars, biofuels, biomethane, etc. are realities from a technical point of view and has become alternatives to the traditional mobility. It is difficult to tell if in the long-term we will witness a new one-technology model. But, in the middle term, it seems clear that they will coexist as they present different advantages and disadvantages and are useful for different applications.
In this context, we must emphasize the interest in recycled fuels of these latest years. Recycled fuels are obtained from organic waste material. This definition includes bioethanol and biodiesel but biomethane is the one with the most potential as the other two need raw materials of a greater quality to be produced.
But, what is biomethane? In Europe anaerobic digestion plants are common. In there, organic material is fermented without oxygen to obtain biogas, composed by a 60% methane and a 40% of carbon dioxide. This kind of gas has an interesting heat power that has been traditionally used to obtain heat and/or electricity, but it is not enough to power a medium-size car. There are different alternatives to get a biogas with a 95% methane concentration so it can be called biomethane:
- Upgrading: Technologies that eliminate the CO2 from the biogas flow: membranes, stripping, etc.
- Methanazation: CO2 reformed with hydrogen so it can be transformed in more methane.
Obviously, each of these alternatives have different possibilities and nuances. For example, the present tendency of upgrading consists of using the extracted CO2 for vegetal growth or as chemical block to obtain interesting products for the industry sector (paints, food, cosmetics, medicine, etc.).
Regarding mobility, biomethane can be used in combustion engines as natural gas, so this kind of vehicles are already in the market: Ford, Volvo, Volkswagen, Iveco or Mercedes-Benz are some brands that have this kind of vehicles available from cars to industrial vehicles and they are even developing adapted farming vehicles.
The Nordic countries are the ones that have made more progress regarding biomethane from a quantitative and qualitative point of view, as happens with everything related to anaerobic digestion. Germany, Sweden and Switzerland have an important network of gas stations that are implemented in the whole countries. There are also very interesting community projects underway, although there are also problems such as in the case of Goteborg.
Anyway, biomethane is a solid and consolidated alternative that has several success cases, as it has been realized by important food business groups in the UK. Coca Cola, Sainsbury or Tesco has biomethane generation plants to generate fuel for their vehicles using their own waste material. So, circular economy models are developed and used both as publicity and to reduce GHG emissions and report important improvements in their result accounts.
Figure 1 – Coca Cola Biomethanation Plant & Gas Station in Enfield (UK), with capacity for 14 trucks. Source
However, we find interesting projects and clear advances in this sector also in Spain. The case of Valdemingómez landfill in Madrid. A pioneer project in Spain that generates biomethane by treating up to 4,000 Nm3/h of biogas that is generated from municipal waste. Biomethane is then use in two ways: it is injected in the natural gas grid and it is also used in 405 urban buses ─25% of the fleet─.
Figure 2 – Valdemingómez Biomethanation Plant in Madrid, Spain. Source
Other projects developed lately are the Vacarisses landfill biogas project in Barcelona or the sewage treatment plant biogas project in Murcia Este.
In the region of Galicia there are also very interesting projects such as the one carried out by Energylab and Naturgy in the Bens landfill in A Coruña. The biomethane produced there is use in urban buses and vehicles of the own installation. Norvento also participates in the project that is now in advanced stages of development.
Figure 3 – Biomethane Urban Bus refueling in Bens Landfield (A Coruña, Spain). Source
Recycled biofuels, specially biomethane, have came to stay. The possibility to obtain fuel from waste material that are expensive to be managed it is an interesting stimulus for large food industries and public administrations. Although it is clear we have a long way ahead and have to face considerable challenges for its implementation. Anyway, in the medium-term, biomethane will be a key actor in the energy and transportation fields if we keep our aim to decarbonize the economy by 2050.