By Tom Denton, Automotive Author
In this, the fourth in a series of articles, exclusive to Automechanika’s auto:resource, I will continue to dispel some of the myths and clear up the FUD around EVs! You may not agree with everything I say, and that’s fine, I may even be wrong – so let’s debate.
If you haven’t yet read them, catch up on Part 1, Part 2 and Part 3 here.
Below, I have presented some claims and issues as statements or questions – and then either agreed or shown them to be untrue. I will also look at some of the genuine issues that need to be solved.
Many people suggest that electric cars are not the only solution, so this article will look in particular at alternative fuels.
Biogas primer
Before we look at some of the comments and questions suggesting biogas as an alternative to EV development, here is some background.
Biogas is the mixture of gases produced by the breakdown of organic matter anaerobically (the absence of oxygen). It mostly consists of methane and carbon dioxide. It can be produced from many sources such as agricultural waste, manure, plants, sewage or food waste. Because of this, biogas is described as a renewable energy source. (Reference)
Figure 15 Biogas plant
Biogas varies but is roughly 50:50 methane (CH4) and carbon dioxide (CO2) but may have small amounts of other chemicals such as hydrogen sulphide (H2S). It can be burned directly as a fuel or treated to remove the CO2 and other gases, for use just like natural gas.
Biogas can be compressed after removing the carbon dioxide and other trace materials. The process is the same as when natural gas is compressed to CNG. In this format it can be used to power motor vehicles – that have been built to use this fuel.
Here in the United Kingdom biogas is estimated to have the potential to replace around 17% of vehicle fuel. The UK Government is planning to scale-up biomethane production to heat around 230,000 homes, rather than use it as a vehicle fuel. Another alternative would be that it is used to create electricity to charge our EVs…
Biomethane
Now to some of the points raised with me in previous debates. The first suggestion was that biofuels such as biomethane can be distributed by infrastructure we already have in place for filling stations.
I fully agree and support the creation and use of biofuels. However, the scale to supply all vehicles is far too complex. Methane can’t be mixed with petrol or diesel so it would have to have a separate transport system (big diesel-powered tankers probably). The fuel stations would then need separate tanks and supply systems. Not impossible but added complexity adds cost and produces emissions.
Changes to engines and fuel systems are also needed to make a car run on CNG and other alternative fuels because of different chemical compositions.
In the UK almost all petrol sold is known as E5 because it contains 5% ethanol – which is created in a broadly similar way to biogas, from sugar cane for example. If higher mixtures are used, the presence of these alcohols in fuel can cause corrosion to metallic fuel system components.
Biofuels are without doubt a good thing and should be used wherever possible. However, I think the plan to make larger digesters that produce fuel for home heating or electricity generation are the better options. Biodiesel is perhaps an area that could be developed further – but again engine modifications may be required for higher percentages.
Figure 16 E85 only for specially adapted engines
The suggestion was made that because methane is 20 times more potent as a greenhouse gas than carbon dioxide, it should be captured wherever possible. I couldn’t agree more, in fact some reliable sources say its global warming potential is 25 times that of CO2. (Reference).
The bottom line for me is that biogas production should be increased as much as possible. But it is not a viable replacement to using crude oil or a reason to stop EV development. Motorsports on the other hand:
Figure 17 Biomethane car for the 24hr Le Mons race (Source: WR Media)
Compressed natural gas (CNG)
Use of natural gas was a suggestion for reducing our carbon footprint. My view here is that it is a small and important step in the right direction, but as mentioned above, IC engines and their fuel systems need to be significantly modified to use CNG. There is also the storage and delivery issue.
Figure 18 CNG Honda Civic from 2012
Most of all however, natural gas is still a hydrocarbon fuel that is ‘dug’ out of the ground so will continue to add CO2 to the atmosphere.
Liquid propane gas (LPG)
We received a question, and it is another good one: Everyone is raving about electric cars and how eco-friendly they are but what about LPG for those of us who can’t afford an EV? Further, the suggestion was that conversions are already common and even new cars are available. And finally, the suggestion was made that LPG is cheap and could be a revenue source
Figure 19 LPG tank takes up boot space, but this is a trade off some people accept
I agree LPG has been a valuable fuel for years for some drivers. Taxis used it a lot at one point until diesel engines improved. Let’s first look at what LPG is, and some of the pros and cons of using it in a vehicle.
Liquefied petroleum gas (LPG) is a clean-burning fossil fuel that can be used to power internal combustion engines. It is a mixture of propane and butane and is often described as propane because that makes up most of the gas. It is refined from crude oil and it can be liquified at room temperature under comparatively low pressure. Its low carbon content means it produces about 10% less CO2 than the equivalent petrol/gasoline engine.
Petrol/gasoline and diesel vehicles can be retrofitted to run on LPG in addition to conventional fuel. The LPG is stored in pressurized fuel tanks, so separate fuel systems are needed in vehicles powered by both LPG and a conventional fuel. It is known as Autogas in Germany, GPL in France and GLP in Italy and Spain.
Figure 20 Filling with LPG (Source: www.flickr.com/photos/davilla)
Traditionally LPG vehicles used a vapour pressure system. Newer liquid injection systems have improved the efficiency considerably. Following are some of the advantages and disadvantages of LPG:
Advantages
- Fewer toxic and smog-forming particulates
- Higher octane rating allowing for higher compression ratio and greater efficiency
- Longest driving range compared to other alternative fuels
- Spark plug life can be extended
- Cheaper than petrol
Disadvantages
- Few cars and limited trucks commercially available
- Less readily available than conventional fuels
- Special delivery and storage facilities are needed
Shell has recently pulled out of supplying LPG in the UK. In response to a question, Shell said:
“LPG is a valuable energy source for numerous business applications in industry and transportation. However, in the UK, customer demand for LPG for domestic transportation is declining and many of our Autogas service stations are increasingly underutilised. As a result, Shell are moving towards offering alternative low-carbon transport fuels such as electric vehicle charging or hydrogen, areas where we are seeing increasing customer demand.”
The bottom line for me with LPG is that, while it is more efficient and cleaner than petrol, it is still a hydrocarbon fuel so adds to atmospheric carbon dioxide when extracted from crude oil and burnt. It is also important to note that only certain quantities of each distillate (product) are available from crude oil refining. It would be difficult therefore to scale LPG up to significant levels. It had an important part to play but I think it is now destined for the BBQ!
Alternate ending
In a completely different world, imagine what things would have been like if in the early 20th century, we had developed biofuels instead of drilling for oil?
Photobioreactor PBR 4000 G IGV Biotech
What if all our fuel came from algae in huge photobioreactors? It’s food for thought, and actually here’s another idea, maybe we could eat the by-products?
