Naked Science Forum

Life Sciences => The Environment => Topic started by: set fair on 19/03/2024 03:34:56

Title: If we used wood for fuel, what % of our energy needs could this supply?
Post by: set fair on 19/03/2024 03:34:56

I'm supposing we could deal with the polutants from the smoke. I mean if we kept felling and replanting. Not assuming the fastest growing but maintaining a mixed forrest.

Title: Re: If we used wood for fuel, what % of our energy needs could this supply?
Post by: alancalverd on 19/03/2024 10:14:42

Hugely dependent on population density and climate. No problem in Canada, Scandinavia (excluding Iceland - no trees!), Scotland, Siberia, maybe some central African states and possibly New Zealand. Almost impossible to make a significant contribution anywhere else.

Title: Re: If we used wood for fuel, what % of our energy needs could this supply?
Post by: paul cotter on 19/03/2024 15:28:53

That is how several civilisations collapsed when all the wood was gone.

Title: Re: If we used wood for fuel, what % of our energy needs could this supply?
Post by: set fair on 19/03/2024 18:13:48

Quote from: alancalverd on 19/03/2024 10:14:42

Hugely dependent on population density and climate.

i'm thinking about the whole world.

Also I realise that there would be a whole host of problems, but thats another question although it makes my question just accademic. To make it a little simpler lets say 5% of Russian and Canadian forest were harvested annually - what % of mankinds energy needs would that provide?

Title: Re: If we used wood for fuel, what % of our energy needs could this supply?
Post by: Origin on 19/03/2024 18:24:19

The major use of wood currently is for fuel.

Title: Re: If we used wood for fuel, what % of our energy needs could this supply?
Post by: alancalverd on 19/03/2024 21:58:49

The population of all the countries I listed totals about 100,000,000and they are probably the only ones where wood burning could be indefinitely sustainable as a source of all artificial energy.

You can estimate 10 MJ/kg as the available energy output from wood burning, about 25% of the energy density of diesel fuel. To sustain a reasonable Western lifestyle you need about 400 MJ per day, say15 tonnes of wood per year. My guess is that there is about 10¹¹ tonnes of live wood on the planet, so you might harvest 5 x 10⁹ tonnes per year with some hope of sustainablity.

There are 8 x 10⁹ humans, so the demand is for 120 x 10⁹ tonnes of wood per annum.

No chance.  But with a bit of scraping and saving, you might just sustain one tenth of the present population at a recognisable (pre-industrial) standard of living by harvesting wood.

Title: Re: If we used wood for fuel, what % of our energy needs could this supply?
Post by: Zer0 on 27/03/2024 17:08:03

@SetFair

Hope you do not mind a follow-up thought...

If ' we ' reduce the Population to around 1 billion, and could manage to accommodate everyone around the Equator, or say go back to a Wandering gypsy lifestyle scavenging resources as they grow & replenish, would that be a feasible plan?

Title: Re: If we used wood for fuel, what % of our energy needs could this supply?
Post by: alancalverd on 27/03/2024 18:07:13

Another approach to the calculation. The Carboniferous period lasted about 60,000,000 years. Suppose 1% of all the trees (i.e. 600,000 years' worth of growth, turned into coal. Coal reserves are estimated  to be sufficient for about 100 years as the primary world source of fuel at current rates of energy consumption. So if we reforested the entire planet and increased the CO2 content of the atmosphere to Carboniferous levels, we could only harvest about 1/6,000 of our energy needs sustainably.