Lecture 3 - part 1 Flashcards
What are the features of petroleum?
- Provides liquid transportation fuels as well as industrial chemicals and materials
- Available in bulk
- Cheap (for now)
- Mature industrial conversion
- Non renewable
- Finite and diminishing resource
- CO2 emitting
- Hazardous and polluting
- Unsustainable
What are the features of plant biomass?
Advantages
- Potential to provide liquid fuels, chemicals and materials
- Abundant
- Renewable
- Potentially CO2 neutral
Disadvantages
- Nascent conversion technologies
- Underdeveloped supply chains
- Sustainability as basis of industrial economy unclear
What two type sof plant biomass are used as fuels?
Non food - lignocellulosic biomass
- Diesel, ethanol, other alcohols
Food - strach, sucrose, oils
- ethanol, other alcohols, bio-diesel
What are the potential sources of linocellulosic plant biomass?
Source of energy rich carbond compounds
- Crop residues (straw, husks, bagasse etc.)
- Timber residues (sawdust, shavings, bark, branches)
- Waste (organic fraction of MSW)
- Dedicated biomass crops (miscanthus, willow)
What are the features of cellulosic biofuels used in lignocellulosic biorefineries?
- Cellulose is a polymer of glucose, which is easy to ferment (made of hexose sugars) using well established commercial microbes
- Cellulose makes up 25-40% of lignocellulosic plant biomass
- Making fuels from cellulose will only be commercially viable if you do something useful with the rest of the biomass (2nd gen biofuel)
What are the different type of biofuels?
•First generation biofuels: biodiesel from plant oils and bioethanol from sugars and starch
•Second generation biofuels - typically cellulosic ethanol
•Advanced biofuels- general catchphrase anything not 1st generation
•Drop-in biofuels; fuels that can be used directly in existing engines (biodiesel, alkanes)
Ethanol: higher octane number than petrol, issues with carrying water but can be produced at high levels, about 50% conversion
What are the ideal features of good biofuels?
- Should significantly reduce carbon emissions compared to fossil fuels; land use change impacts should be factored into calculations of this
- Should be commercially viable (current changes in viability due to middle east, price of oil dropped massively to try and beat competitiors)
- Should not exacerbate food security (land use change - expanding agricultural production for biofuels can lose forest or other C-rich ecosytem)
What is the potential to use waste as source of road transport fuel in the future?
2015 Europeon Climate Federation
- if all wastes and residues sustainably available in the EU converted to biofuels -> supply 16% of road transport fuel in 2030
- if sourced sustainably, reduce GHG in excess of 60%
- but must be aware of sustainable land management practices - maintain carbon balances, safeguard biodiversity, water resources and soil functionality
- increase revenue into rural ecomony - addittion 15 billion euros, up to 300 000 additional jobs by 2030
What are the features of the potential GHG savings using selected wastes and residues instead of fossil diesel and gasoline?
89% saving of C compared to fossil fuels if use wheat straw (ethanol)
296% saving if use municipal solid waste ethanol - lots of C saving AND reducing waste
When looking at levels of global feedstocks - what waste is produced? Where is the potential for this?
Around 30% wates (agricultural residues available worldwide)
Could supply a lot of liquid transportation fuel needs
What are the advatages of perrenial dedicated biomass crops?
- Plant once in 10-20 year cycle
- Store resources in root systems - lead to little soil erosion/run-off (c reserve in roots, increases soil C) - can regenerate if die back in winter
- Can lead to net carbon capture
- Require little input in terms of fertiliser and pesticide
- C4 Grasses are generally more productive and better drought tolerant
- May grow on more marginal land than food crops
- Over 1 billion Ha of abandoned or poor-yielding agricultural land globally that could be used for this
What crops are the best 1st generation biofuel crops?
Sugar cane
- up to 100t/Ha DM (15t sugar)
- only grows in tropics
- contribute to food security
Palm oil
- 20T/Ha Oil per year
- only grows in tropics
- loss of tropical forest
Compare to oil seed rape: 2T/Ha at best, 10X more land needed than palm oil
What could be a substitute for sugar can grown in the UK?
Sugar beeet grown in N.yorkshire can produce a similar level of sugar per Ha as sugarcan in Brazil. But little biomass.
What are the features of agave as a purely lignocellulosic crop?
- High yielding sugar
- Drought resistant
- Low input
- Little competition with food production
- Produce fibres (sisal)
- Sugars used to make Tequilla in Mexico
