Science Interviews


Tue, 26th Jul 2016

Brilliant biofuels?

Dr Christopher Chuck, The University of Bath

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We could keep refining the burning process of crude oil to make the system as Refining sugarcane for biofuelsefficient as possible, but why do we have to use fossil fuels at all? Biofuels have been around for the last few decades and they can be used in pre existing engines. But if theyíre so great, why do they only make up a tiny fraction of the fuel we put in our tanks? Chris Chuck is a researcher from the University of Bath and he took Kat Arney through the basics of biofuels...

Chris - Well simply, a biofuel is just a liquid fuel where most of the molecule, if not all of the molecule, is derived from a source of biomass. Now this biomass could be vegetable oil, sugars, plants, grass, waste food, any type of plant biomass.

Kat - When we hear about people running their cars off old chip fat - thatís a biofuel?

Chris - Thatís absolutely a biofuel. Yes, that was one of the early ones.

Kat - In places like Brazil, as well, they run cars of ethanol  and thatís derived from plants as well?

Chris -   Yes, so in Brazil theyíre using sugar cane. Theyíre growing sugar cane in the vast areas of lands that are suitable for that and turning it into ethanol; itís one of the most successful biofuels on the market.

Kat - So weíve got all these different biofuels from different sources - what are some of these sources? Youíve talked briefly about some of them and are they all the same, are they all just equivalently good or bad?

Chris - Thereís a great diversity of biofuels either on the market or being developed at the moment. Some are to fit the role of petrol, diesel, or aviation fuel, which all have different properties. In other kinds, itís where you actually derive them from.

So we really have two definitions of a biofuel whether itís a first generation biofuel, made from food matter or itís grown on land needed for food production. Or second generation biofuels where the biomass doesnít compete with food and this is a much, much bigger resource. So we can talk about agricultural residues, forestry waste, waste food, even algae and seaweed thatís produced biofuels from this. Now because theyíre so diverse these different types of biomass, we have to use lots of different chemical and biological processes to make the fuels from them.

Kat - And does this mean that, actually, they may be not as efficient as just drilling the stuff out of the ground?

Chris - Well yes, it very much depends on what land area youíve got to grow them on, whatís in place in terms of the infrastructure to make them, for example, bioethanol from sugarcane has been very well developed in Brazil and is actually a lot of the time, depending on the cost of a barrel of oil, cheaper than petrol there on the market as well. But most of whatís limiting biofuel manufacture at the moment is actually the cost implications.

Kat - There is this question though because itís being estimated that the fossil fuels that we have for car fuels and that kind of thing, weíve probably got a little bit more than we thought we had. And if the idea is that weíll eventually all be running on electric cars, are biofuels really more like just a stopgap? Do we need to put time, and effort, and money into making them a replacement for fossil fuels?

Chris - Well this is quite a common misconception. Now a lot of people have been looking at what our energy mix will look like in 2050 or even 2100. Everyone disagrees entirely on the numbers and what it can be made up of. But one thing all of these major models have suggested is that we need to increase the amount of biofuels being used and, if you take a rough average, itís approximately 50% of our transport fuel will need to come from biofuels by 2050. And our electricity networks and other forms of energy generation just canít meet that gap.

Kat - Obviously things like plants, you use carbon dioxide to grow; theyíre taking carbon dioxide out of the environment. Is that alteration of the carbon balance something we should be taking into account almost regardless of the cost?

Chris - Absolutely! Itís very complex to work out whether a biofuel actually is sustainable, actually is reducing carbon emissions on using fossil fuels and, in the last few decades, weíve been developing the tools made in life cycle assessment to be able to make those statements, to be able to understand that. And so we really need drivers to push the biofuels which are showing very big promise in reducing greenhouse gas emissions.

Kat - Because, I guess, theyíre taking the carbon dioxide in from the environment, youíre still burning it and putting it back out, but thatís almost like a closed loop, I suppose?

Chris - Absolutely, but then you have to work out how much energy are you putting in transporting the biomass, drying the biomass, using the fertilisers even to grow the crops. So you can have enormous energy inputs without really counting them unless youíre careful. Itís very important that you assess exactly how a biofuel is made from growing it in the field all the way to emissions when youíve burnt it.

Kat - And just very briefly - are biofuels already out there? Could I be putting biofuels in my car or using biofuels in a way that maybe I donít realise?

Chris - Absolutely! About 5% of total transport fuel in the world is now biofuel but, ultimately, you are using them and youíve probably used them today already. Theyíre doped into fuels at a few percent just to get them into the infrastructure and so thereís not a great choice that you can say - Iím going to use biofuel or not use biofuel. Itís already a percentage in the fuel that we already use.


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