Noting that parent was referring to net primary productivity (on which, Jeffrey Dukes, "Burning Buried Sunshine", is very strongly recommended: http://globalecology.stanford.edu/DGE/Dukes/Dukes_ClimChange...), the sustainability of various renewable energy technologies is an open question.
But here's the dilemma as I see it:
• Modern technological civilization is predicated on abundant cheap (high EROEI) energy sources. Technology follows from, rather than leads to, energy availability, and hence isn't an answer.
• For reasons of both depletion (peak oil / gas / coal) and pollution (greenhouse gasses, AGW, mercury and other emissions), continued use of fossil fuels isn't viable. We've already heat peak conventional liquids (oil), and global total peak oil production is likely within 5-15 years. Gas follows shortly after, coal likely by the late 21st / mid 22nd century assuming demand doesn't collapse entirely (which would generally indicate a collapse of civilization).
• If you want to continue a technological civilization of some sort, then you've got to find alternative high-grade forms of energy. Likely a mix of electrical generation (highly fungible) and limited liquid or solid fuels production (for transport and storage needs). Capacities to produce both are fairly constrained.
• The alternative is ... a non-technological level of civilization. Likely a collapse in both technological levels and population (from famine, disease, war, the usual). Which means that the future of humanity will be relying on solar power -- collected and stored by plants. And be living in a drastically depleted environment in which many ores and mineral resources, as well as water, topsoil, and ecosystems have been hugely depleted. "Rebooting" civilization would be at best very, very difficult.
• I like a technological civilization, don't get me wrong. But I don't see it as sustainable. And there's nothing in the laws of physics, chemistry, biology, ecology, or geology which say the Universe owes us our standard of living.
Answering your question about solar PV: the economics look difficult, and numerous people who are convinced of peak oil and climate change suggest that they may well not work, see Ted Trainer, John Michael Greer, Charles A.S. Hall, and Gail Tverberg among them:
But that doesn't exactly leave us with good alternatives, and my feeling is that PV or other high-grade solar technologies (solar thermal, Stirling or related engines) are worth pursuing with our remaining fossil fuel reserve (we really should have been pursuing these decades ago).
Nuclear. I notice you don't mention this at all, unless you mean to include it in "electrical generation", in which case your statement that technological civilization is not sustainable strikes me as far too pessimistic. Even if you only consider nuclear to be a temporary energy source while we develop high-grade solar energy, it still can get us a lot further than our remaining fossil fuels.
Also, any evaluation of "sustainability" is fundamentally limited by our inability to predict how our society will change in the future. For example, a sustainability analysis done in the late 19th century, when horses were a primary mode of transportation, would have shown that that mode of transportation was not sustainable--we would have ended up, as the saying goes, knee deep in horses--t. Then the automobile came along.
In other words, there's a common confusion (as shown by many posts in this thread) between a specific way of doing things being unsustainable, and our society in general being unsustainable. It's far harder to show the latter than the former, because we can always change our way of doing things.
Keep in mind that uranium is also a limited resource. Might last us another thousand years,but it will run out eventually. Unless by nuclear you meant fusion power,but we are not quite there yet.
In a thousand years we'll have fusion power--in fact we'll probably have better sources of energy than fusion (like the ability to tap solar energy much more efficiently than we do now).
Great! Fission or fusion? What fuel cycle? What reactor design? Is it proven? Experimentally? Prototype? In production?
What's the fuel availability look like? How about issues with proliferation, waste disposal, plant accidents, and plant decommissioning?
I didn't spell out my alternatives in detail, but yes, nuclear is an option for electrical generation (I suppose you could also run a power loom or stamping gin off of one if you really wanted to). However of the options:
• Fusion's not there yet. Tokamak, NIF, or Polywell. Nothing but the shortest experimental possible ignitions yet. Nothing remotely commercializable. Several fuel cycles are fairly constrained.
• Uranium/plutonium LWR fission has a pretty critical fuel shortage. 80 years at present usage, 6 if we go 100% nuclear at present energy consumption rates. Scale in anticipated global energy growth rates and it's less than that. Waste, decommissioning, and accident issues are significant.
• Breeding uranium or plutonium might extend fuel supplies but creates significant weapons-grade material proliferation concerns.
• The TeraPower "nuclear candle" is a nice bridge technology ... if it works, but that only lasts until our existing nuclear waste is consumed (which raises the point: you don't want to be too good at disposal: the stuff might come in handy).
• Thorium has a vocal and occasionally demented lobby on the Intarwebs, but even the optimistic Chinese see MSR as 25 years out from commercialization.
And I see energy needs coming to a head Real Soon Now -- rather less than 25 years, at any rate.
And none of these technologies, nor wind, solar, geothermal, hydro, or tidal power give you liquid fuels, which is what planes, trains, automobiles, trucks, buses, boats, construction equipment, furnaces, generators, back-up power systems, and remote energy applications rely on. Sure, you've got Fischer-Tropsch, the Sabatier reaction, and other solid-to-liquid, gas-to-liquid, and fuel synthesis processes. All of which, scaled to the 100 million barrels of oil consumed daily globally would represent an absolutely massive investment of capital and energy.
Conventional crop biofuels, wastestream-to-energy, sewage-to-energy, and advanced algael biofuels all suffer from the challenge that your dealing with net captured flux of around 10 W/meter^2, maybe 100 W/meter^2 for algae, of photosynthetic efficiency. And you've got to capture that on land that's not already producing food you're planning on eating, or ecosystems you're planning on sustaining, you know, the rest of the Earth's biosystems.
The 100 quadrillion BTUs the USofA consumes annually corresponds to 29,307 TWh of energy, which at 10W/m^2 and 8 hours of effective insolation (a typical 30% duty cycle) means you're looking at 1,115,186 km^2 ... or a square 1056 km on a side (430,576 square miles, or 656 miles on a side, for the non-metric).
Sure, NYC of 1894 had 200,000 horses pumping out, literally, 5 million pounds of horseshit daily (https://ffbsccn.wordpress.com/2009/11/17/superfreakonomics-a...). And the straight estimates were accurate: keep that up and you'd be buried in the stuff (you already were knee deep in places).
Thing is: it's possible for things to get that bad. Ever been to India? Or just seen the opening sequence of Slumdog Millionaire? Because that's how a lot of people live: combing through trash heaps and swimming in shit (not equine, either).
And the reason NYC didn't drown in brown is because of this one-time lottery winnings of uncomposted Carboninferous lignan-laced pulp and algae decay which we've been talking about here (if decomposers had evolved slightly faster, we'd be discussing this in a small agrarian village somewhere). Technology, as I said, followed that windfall, it didn't create it (Colonel Drake's oil rig: borrowed from the Chinese who'd been drilling 1000 feet for salt since the year 1000). That rabbit's already been pulled from the hat, and we've been looking for a long time, pretty thoroughly, without finding many more rabbits for, oh, 40 years or so. The automobile didn't "come along", it was pumped from an oil well that's now running dry despite fracking fluids leaking into your water supply.
Technology doesn't create entropic gradients, it taps them. And we've got a pretty good idea of what provides useful energy: Moving stuff, falling stuff, blowing stuff, bright light, chemical bonds, and nuclear bonds. And it's mostly the bright light and chemicals that seem to work well for us, higher up it's not sufficiently dense or reliable, lower down and it's too complex. I don't see gradients (flows or stocks) we can tap with the ease and usefulness we have for the past 250 years.
We have plenty of existing nuclear plants that can provide cleaner energy than we get from fossil fuels. Per unit of energy consumed, even the existing nuclear plants are much safer than fossil fuels even when you count the harm from Chernobyl and Fukushima.
Uranium/plutonium LWR fission has a pretty critical fuel shortage.
These numbers are way too pessimistic; they are produced by the same sort of calculations that said we would run out of oil by the turn of the millennium, because they didn't take into account the continuing discovery of new reserves. They also don't take into account breeders; if there are concerns about weapons-grade material being created, you guard the plant (the material doesn't need to be transported, it just stays at the reactor until it's used).
With nuclear fission there's an additional consideration as well: the cost of the fuel is only a percent or so of the total cost per kW-hr, whereas for fossil fuels it's something like 1/3 to 1/2 of the total cost per kW-hr. So it doesn't take a lot of increase in the price of oil to make fossil fuel electricity much more expensive; but even a large increase in the price of uranium doesn't increase the price of nuclear-generated electricity very much. And there's a lot of uranium that could be extracted at, say, 10 times the current unit cost; by some estimates we can extract uranium from seawater at that cost, which increases the time horizon to thousands of years if not more.
I see energy needs coming to a head Real Soon Now -- rather less than 25 years, at any rate.
Same comment as above: I think this is way too pessimistic.
none of these technologies, nor wind, solar, geothermal, hydro, or tidal power give you liquid fuels
Two comments here: first, improved battery technology; second, algae fuel.
that's how a lot of people live: combing through trash heaps and swimming in shit
We already have the technology to fix this; the reasons so many people don't (yet) benefit from that are political, not technical.
I don't see gradients (flows or stocks) we can tap with the ease and usefulness we have for the past 250 years.
Again, way too pessimistic. It's not that I don't see obstacles, but once again, the main ones I see are political, not technical.
For liquid fuels I'd strongly suggest you check recent trends: BP's annual statistical review, CapEx spends and yields from Shell, BP, and Exxon, and projections from the EIA and IEA -- this isn't the Peaker fringe, by a long shot.
algae fuel
Tell me how much algae fuel you want and what conversion pathways (biodiesel, ethanol, synthesis, solids) you're referring to. Then give me acreages and water estimates. Oh, and how you're going to fertilize all that goop and keep pests out of it.
You've done some hand waves but I've seen no sources. Who or what do you rely on for information, estimates, models, or whatever else serves as the foundation for your optimism?
this MIT study for ~100 years supply at present rates of consumption
P. 12 of that study says "most commentators conclude that a half century of unimpeded growth is possible", and the study appears to agree with that assessment. "Unimpeded growth" means a large increase in consumption rate over the present.
Also, that assessment is based on a once-through fuel cycle and mining as the only uranium source. Over a half century to a century time scale the first assumption is almost certainly invalid (breeder technology is advancing) and the second may be shaky as well. (Note, btw, that a key reason why the MIT study assumed a once-through fuel cycle was not that breeders were not available, but that they were uneconomic at current uranium prices; but obviously if uranium gets scarcer, uranium prices go up and breeders become economically viable.)
Finally, a half century is not 25 years. If we have a half century to a century of nuclear power even with a once-through fuel cycle, we have an obvious alternative to fossil fuels for that time frame. Your claim that we will hit an energy crisis in 25 years assumes that there is no such alternative.
Tell me how much algae fuel you want and what conversion pathways (biodiesel, ethanol, synthesis, solids) you're referring to. Then give me acreages and water estimates. Oh, and how you're going to fertilize all that goop and keep pests out of it.
All of which are issues that are going to be solved, if they're not solved already, probably well within your 25 years, certainly within a half century. Google turns up plenty of hits on "algae fuel" or "algae fuel study" that show plenty of progress in this area.
the foundation for your optimism
Human ingenuity plus profit motive plus an obvious market for cleaner forms of energy. What I noted above with regard to the assessment of breeders being viable is true more generally: a key limitation of most assessments of available energy resources is that they only look at what's economical given current prices, not what's possible. But the economics will change.
That's not to say that there are no obstacles; but as I said before, the main obstacles I see are political, not technical.
P. 12 of that study says "most commentators conclude that a half century of unimpeded growth is possible", and the study appears to agree with that assessment. "Unimpeded growth" means a large increase in consumption rate over the present.
Um. No. First, the term isn't defined or clarified, so you're simply applying an interpretation convenient to you. On page 3 you'll find growth assumptions clearly stated:
[T]he study explicitly assessed the challenges of a scenario in which nuclear power capacity expands from approximately 100 GWe in the United States in 2000 to 300 GWe at mid-century (from 340 to 1000 GWe globally), thereby enabling an increase in nuclear power's approximately 20% share of U.S. electricity generation to about 30% (from 16% to 20% globally).
That is the growth which can occur unimpeded for up to 50 years.
You've also conveniently failed acknowledge the first half of that sentence, given in full here with the pargraph it occurs in:
Table 2 shows Red Book identified resources, undiscovered resources, and the number of reactor years of fuel provided by those resources. Based on the total projected Red Book resources recoverable at a cost less than $130/kg (2006$) of about 13 million metric tons (hence about an 80 year supply for 800 reactors), most commentators conclude that a half century of unimpeded growth is possible, especially since resources costing several hundred dollars per kilogram (not estimated in the Red Book) would also be economically usable.
We're still left with 80 years supply for 800 1 GWe reactors. Better than the near-term critical situation for liquid fuels, but hardly copiously abundant.
On Algae:
All of which are issues that are going to be solved
Yeah. So, Boeing's just released "the biggest breakthrough that there is out there" in biofuels, those are its director of sustainable aviation fuels, Darrin Morgan's words, not mine. Halophyte (pickleweed) farming integrated with aquaculture for aviation fuel production at ~75 gallons/acre-year. Aviation fuel is around 5% of total US oil consumption (15,998 million gallons in 2013, RITA), roughly 1 million of the 20 million barrels of oil consumed daily in the US.
Supplying just 5% of US oil consumption from pickleweed would require 21.3 million acres under cultivation. That's about 330,000 mile^2, or a region 577 miles on a side. You could start in Shreveport, LA, and drive all the way around Oklahoma and Kansas without ever entering them. Boeing's article mentions having "thousands and thousands of hectares* under cultivation. How about millions and millions?
Algae are, typically, about 10x more productive than plants, but present their own host of challenges (infrastructure and capital requirements, disease, water, fertilizer, waste removal, plumbing issues). Since the above calculations are for a 5% replacement of petroleum, you could take the same acreage and say instead you're getting 50% of present oil usage. Realize that those 21.3 million acres _now all have to be constructed_ with pumps, drainage, etc. And somehow supplied with water. And placed somewhere that they don't interfere with existing food, habitation, and essential ecosystems.
Good luck with that.
Human ingenuity
Can you demonstrate a single case in which human ingenuity has created a new entropic gradient to exploit, rather than found an existing one? What existing gradients can you point to that we can tap? We've covered nuclear and biofuels here. I see solar, wind, geothermal, hydro, and tide/wave left.
That is the growth which can occur unimpeded for up to 50 years.
I'm not sure those two quotes are talking about the same thing. I notice that different numbers are quoted in different statements in the document; for example, on p. 12 there is this statement:
This reinforces the observation in the 2003 MIT study that “We believe that the world-wide supply of uranium ore is sufficient to fuel the deployment of 1000 reactors over the next half century.”
Which is different from the "80 years for 800 reactors" statement.
But more importantly, you're ignoring additional information that's given in the same sentence we've been quoting and the one immediately following it. You expanded the quote to give the first half of the sentence, but you conveniently ignored the last part of the sentence, which I'll repeat: especially since resources costing several hundred dollars per kilogram (not estimated in the Red Book) would also be economically usable. I.e., the "80 years for 800 reactors" figure (and by implication the "1000 reactors over the next half century" figure) does not include all estimated resources. The very next sentence is:
Using a probabilistic resources versus cost model to extend Red Book data, we estimate an order of magnitude larger resources at a tolerable doubling of prices.
I.e., at twice the current uranium price (which, as I noted before, would mean only a small increase in the price of nuclear electricity to the end user, unlike fossil fuels where fuel cost is a major factor in end user price), we have 10 times as much available, meaning 80 years for 8000 reactors, or 10,000 reactors over the next half century. That's a big difference. And since uranium prices will certainly go up if it becomes scarcer, there will be natural economic forces driving people to tap the 10 times as much uranium that's available at higher prices. So you are conveniently failing to acknowledge information that's in the document you linked to. (And that's still leaving out breeders, which as I noted before, were left out of the MIT study for economic reasons, not technical reasons, and as uranium prices go up the economics change.)
those 21.3 million acres
Or about 23 percent of the area currently under cultivation in the U.S. (922 million acres according to Wikipedia). But we're talking about 25 to 50 years, not right now. There's no reason why algae acres have to displace current farm acres on that time scale. That 21.3 million acres is about 9 percent of the land area of the U.S, which is significant but doable. Or, if we wanted to get creative, we could put the algae farms on platforms offshore and out of the way (and with easy access to fresh water using desalinization rigs--or even using salt-water tolerant algae).
Good luck with that.
In the next 25 to 50 years, the items you list are easily doable. That's not to say they'll actually be done; but once again, the main obstacles I see are political, not technical. I notice you haven't commented on that at all.
Can you demonstrate a single case in which human ingenuity has created a new entropic gradient to exploit, rather than found an existing one?
Of course not; that would violate the second law of thermodynamics.
What existing gradients can you point to that we can tap?
Here on Earth, for the near future, you've covered all the significant ones I'm aware of (assuming solar includes solar thermal as well as photovoltaic; I haven't seen a lot lately on solar thermal, but it seems like an obvious alternative worth pursuing).
There is enough uranium in Australia to last us a few ten thousands years. Sure, fossil fuels are cheaper to harness right now, but they are nowhere near what is possible and feasible.
Not according to any analysis I've seen, most of which project about 80 years' supply at present usage rates. Six if we lean on nuclear for 100% of energy needs.
The Wiki article you link lists a variety of predictions on global peak uranium. The pessimistic ones, which are a minority, mostly predict that it has already happened (1980, or so). There appear to be 3 predictions that average around 80 years, and one predicts with a 6-fold increase in consumption it would last 12 years.
Meanwhile there are just as many optimistic predictions that it will last for thousands of years, if not longer. What makes you so sure it's only 80/6?
The problem with your reasoning is that you neglect the fact, as do almost all humans in technological societies, that easily 90% of the energy we consume is wasted. You are not to blame; when you have no firsthand experience of a thing, it is normal for one to be oblivious to its existence.
I have lived for many years within the energy budget provided by photovoltaics and the wind. It is possible to live well under such circumstances, and to be as technological as a city dweller, but first you have to eliminate the waste.
Take, for example, your houses and apartment buildings. They are so poorly constructed that the planet would be considerably better off, despite the waste, if we tore down every single last one of them and rebuilt them for longevity and energy efficiency.
A few buildings (maybe three in a city of 5 million people) are constructed well. They use (at the moment) ICF techniques and they are so well insulated that, even in the coldest days of January, the heating system can fail completely for over three days BEFORE ANYONE NOTICES that it is broken. They can use geothermal heating exclusively both winter and summer and provide complete comfort for 10% of the normal cost.
But you do not build your stuctures like this because energy efficiency is not a priority; money is the priority. The scumbag builders build shit buildings to maximize their profits; the scumbag realtors sell units to the ignorant masses for a fortune, and nothing changes.
What is wrong with humanity is that we are just too fucking stupid and far too much in love with ourselves to do the reasonable thing. We are crazy for money and it has become the arbiter of all success. Instead of killing off 90% of the species, we could begin by simply eliminating the 90% of our activity that is wilfully wasted and continue to live well, so long as the reduction in resource usage was not simply an excuse to increase our already ridiculous numbers.
So that is my alternative: stop being monsters. Otherwise I cast my vote for us all to die of a virus incubated in the backstreets of Shenzhen, and good riddance.
