Renewable resources should be exploited in a manner such that:
(1) harvesting rates do not exceed regeneration rates; and
(2) waste emissions do not exceed the renewable assimilative capacity of the local environment.

Balancing Nonrenewable and Renewable Resources
Nonrenewable resources should be depleted at a rate equal to the rate of creation of renewable substitutes.

Link is here written by Herman Daly

Here's another link to a lecture by Saul Griffth who has crunched the numbers in terms of Renewable Energy. By his own admission he's an optimist Saul Griffth pdf lecture, its over 7mb. Reading the numbers didn't make me feel over optimistic so I've got no idea why he is!

Sustainability needs a time reference, but if someone means for more than a generation there doesn't appear to be anything that looks remotely sustainable about our energy/resource consumption. Perhaps humans can solve environmental and energy problems, just the probability of a slimed down population looks high. I guess Gaia will tell humans what's sustainable in the end!

I thought the only thing sustainable was daily or stored photosynthesis .... if so

are we talking batteries and PV panels

OR

trees - firewood

plants - food

or ??

Interesting Venn diagram, and interesting evaluation grid.

But some more-or-less obvious criteria perhaps should be added, such as: () Does the production of the fuel compete too vigourously with other necessities, such as food? () Can the environment absorb and neutralize (detoxify) waste products from fuel production at least as fast as they are being produced?

I agree that looking at the demands of sustainability in the various relevant categories can cut through a lot of nonsense.

Gail the Actuary said:

I wrote this post to try to get people to start do a little more thinking

A little more thinking, Gail, is not inventing your own definitions of sustainability.

mikeB said:

Is sustainable: "capable of being maintained indefinitely?" Or is it: "capable of being maintained over such a period of our choosing that it comforts us?"

This is a very important question. If one want to talk about "sustainable" then one can't include riders like "over x years or centuries", because fresh, and possibly greater, problems arise as the end of that time period approaches. If you add a time period then you are making a totally arbitrary statement. Your time period might not match with anyone else's.

If we use a time period of "indefinitely" then we cover all bases, over which we have some control (obviously, we can't take much account of asteroid strikes, super-volcanoes and the like). So why include so-called sustainability criteria like the cost of increased capacity?

Growth is not sustainable. Period.

If we want energy, we need to figure out how to use whatever the resource is only at a sustainable rate and in a sustainable way, otherwise it is unsustainable, by definition. Sustainability means not consuming any resource (renewable or non-renewable) beyond its renewal rate and not damaging our habitat in a way that might negatively impact our ability to survive. These are the only criteria you should be considering, Gale, at least as far as sustainability is concerned. Obviously, it will take a while to get there and there are certainly population issues to address, but we aren't going to get there by assuming any non-renewable fuel is sustainable or that any renewable energy source can be used at any amount.

Not all countries that have what might be called high living standards have zero or negative population growth, even without immigration. Even supposing the hypothesis is true, what standard of living will suffice, what will the population be, at that time, and what will the resource consumption rates be?

I don't think it's as simple as saying we need to raise living standards everywhere. Read the articles in the New Scientist special report for more opinion on how growth is unsustainable, including Does growth really help the poor?

We have finite lifespans - it is hard for me to imagine we will ever depress our discount rates to such an extent that we value something in 10 years as much as we value the present moment.

You may well be right about the discounting, but I hope not. If so, I think that means we are truly screwed. On an individual level, human lifespan is finite, but taken in a species context, the lifespan of humanity is more on a societal time span (maybe even geological...if you're an optimist ;-). As long as humans are creating future generations, those generations will have needs and uses for the resources of this planet. Discounting those future needs relative to our own current needs cannot lead to anything but short-term, unsustainable decision making and behavior. Unless we, as a species, can begin to value the well being of our children and their children on par with our own, then long-term planning is essentially impossible.

So I understand what you are saying. Is that approach possible today? Socially? Politically? Economically? Obviously not. But if we cannot, over time, change those philosophies, then "sustainability" (under whatever name you choose to give it) is truly unattainable and the best we can do is to choose whether to screw over the next generation, or some generation after that (essentially, business as usual).

Based on your writing, I'm obviously not saying anything you don't know. I just worry about the moral hazard of allowing other people to define the language of the debate. If we mean sustainable, say sustainable. Define the word. Debate the word. Point out and criticize any use of the word you don't agree with (e.g., sustainable growth), but don't abandon the term to people whose only interest is the continuation of a business as usual, resource-wasting, short-term profit taking, exponential growth system that is patently not sustainable, durable, reliable, resilient, or any other positive long-term-oriented thing you choose to measure by.

Sustainability (in my opinion) requires that future needs have the same value as present needs. Durability, reliability, resilience do not. Discounting is fundamentally in conflict with sustainability. If we give up our right to define the language of the debate, we abandon the debate, and we lose the debate.

Just one man's opinion.

Brian

I wish the word sustainable and Green could be banned when discussing either environmental or energy issues. It seems to be used most often by politicians who want to support their BAU policies.

I have stopped using the word 'sustainable'. "Durable" seems more in line with what we are trying to accomplish.

It seems to me this is abandoning all hope of the boom/bust cycle. Nature shows B/B is the norm, so perhaps that is the right outlook so as to avoid taking Mother Nature on mano-a-mano.

I'm not quite ready to give up on building (relatively) cooperative societies, at least cooperative enough to manage resources intelligently. Of course this involves people standing against those who would attempt to gather to themselves more power and wealth than is in the public interest, extensive public discourse, etc.

Perhaps the limits we are imposing upon ourselves via our profligate past and present will be unambiguous enough to wipe away any illusions that we have any other choice if we hope to succeed as a coherent civilization.

It seems to me that abundant resources have allowed the oppressed/poor/etc. to imagine themselves as one of the wealthy and powerful, making them willing to accept the excesses of others in pursuit of the dream for themselves. But will that continue as constraints make it increasingly clear that the concentration of wealth and power puts a permanent limit on their ability to improve their lives? Might this not encourage a great move towards the Commons and away from monopolies of wealth and power?

Things to ponder...

Cheers

One thing I thought about writing about, but didn't find a place for, was the idea of bridge technologies. Here again, we presumably are talking about a limited time frame, so we don't want to put huge investment in temporary infrastructure.

I would think the ultimate energy would be something other than uranium based nuclear. Perhaps thorium based nuclear, if we could figure out how to do this, and scale it up in a sensible manner. It may also be possible to scale up heavy oil production over a long period, to provide some liquid fuel (with CO2) as well.