Researchers suggest that biofuels such as ethanol and biodiesel could at best replace a third of petroleum based fuel. That's for cars, trucks, planes, trains and agricultural machinery. When oil is gone say by 2040 it means we'll be immobile and starving unless there are alternatives. Milking a cow on an 800 sqm block in Melbourne is probably not practical.

For several years I ran a ute on home made biodiesel until the injectors snotted up. That process consumed methanol another alcohol like ethanol but made from natural gas. Bio-ethanol is a minor helper and is delaying the search for a total oil replacement. Techno fantasists think we can run combine harvesters on solar batteries not liquid fuel. Let's content ourselves with that idea.

In those intervening years global population has gone from about 2.5 billion consumers to over 8 billion consumers.
Therein lies the problem.

Thanks Viv Forbes: An enjoyable article with flavours of Albert Facey’s “A Fortunate Life”.

Yup, been there, done that.
Alan B.

Tas, Biodiesel can be sourced from diesel trees, some green blue algae, native wisteria and sunflower seed/oil seeds/peanuts etc.

Most need some refining to remove soluble wax content that, as you say, clogs the injectors.

Blue green algae are probably the best and easiest to grow as a commercial operation that consumes less than 2% of the water of traditional irrigated agriculture.

Moreover, the next enduring long-term drought, (and we will have many in the foreseeable future) may be the only viable agriculture option on many farms!

Refining may be limited to simple chill filtering though sand filters that remove any soluble wax.

Oil is also a product of algae that was laid down thousands of years ago. No need to wait or rely on price gouging oil barons.

Furthermore, it's also a carbon neutral option as are all the other above options.

New processes (yeast variety) may make sugar cane an excellent source of petrol replacing fuel/ethanol? That could be combined with some of or all the above, to make endlessly sustainable jet fuel/power kerosene?
Alan B.

Alan B I don't think biofuel problems are as easily solved as you suggest. That covers quantity, quality and price. For example aircraft biofuel has to stay liquid not gelatinous in subzero conditions. Some say forget the bio- part and move to e-fuels made from electricity, air and water combining green hydrogen with scrubbed CO2. Sounds great except for the price. Will motorists pay $10 per litre for e-petrol? The delusion of green growth and high population could be the biggest mistake humans will ever make.