New nuclear power stations - is there really a case?

[Crispy]

Quite. As you can see from the quote I posted above.

This is why I'm am trying to persuade Serguei to have a discussion based on evidence rather than simply making unsupported assertions.

I wish you the very best of luck.

 

[Bernie Gunther]

In terms of food security, the uk has about 60m people and about 60m acres of land. So that's one acre per human, roughly. About 20% of that land is classified as 'arable' (ie prime farm land). (source CIA world factbook)

So lets take that 20% per human and see what we can do with it. 20% of an acre is 8700 sq ft roughly. We're also a nation of gardeners, so we can probably assume quite a bit more than 8700 sq ft is potentially available for food production, through methods such as Cuban style urban agriculture, but let's not for now. Instead let's look at what production figures might be reasonable to assume for sustainable agriculture.

Jeavons (researching in California) has shown that a complete nutritionally balanced diet can be produced using an area as small as 2,800 sq. ft. (270sq metres).

http://www.cityfarmer.org/barrsUAvanc.html

Now, that's California, so we might have to adjust those figures a bit for the UK, but on the other hand it shows that the potential is definitely there. As long as we are prepared to give up the profitability advantages of industrial agriculture to get the superior yields of small scale sustainable agriculture.

 

[Serguei]

No, a lot less.

But one can still say that "renewable energy industry claims that it'll provide energy without greenhouse gas emissions" are untrue. Exactly what Bernie Gunther said about nuclear industry claims.

But for both - renewable and nuclear energy industries, it is true to say that greenhouse gas emissions are negligible if compared with burning fossil fuel.

 

[Serguei]

So lets take that 20% per human and see what we can do with it. 20% of an acre is 8700 sq ft roughly. We're also a nation of gardeners, so we can probably assume quite a bit more than 8700 sq ft is potentially available for food production, through methods such as Cuban style urban agriculture, but let's not for now. Instead let's look at what production figures might be reasonable to assume for sustainable agriculture.

So you proposing to make everybody living in the UK to start growing vegetables and keep pigs in their gardens and you think this will allow us all to stop buying food in supermarkets?

As long as we are prepared to give up the profitability advantages of industrial agriculture to get the superior yields of small scale sustainable agriculture.

What superior yields? Where they come from?
As far as I know the yields never in history were as high as they are now - times of industrial agriculture.

 

[Bernie Gunther]

<snip> What superior yields? Where they come from?
As far as I know the yields never in history were as high as they are now - times of industrial agriculture.

Yields per effort are certainly greater with industrial agriculture so for example, around end of the 19th century it took one farmer to grow food for 2.5 people, whereas now one farmer can grow food for 130 people. source

This is achieved by substituting expensive human labour with cheap fossil fuels and has a number of severe disadvantages, from ecosystem damage to dependence on limited oil stocks continuing to be cheaper than human or animal labour. If the oil ever stops being cheaper than human or animal labour (see e.g. this pdf ), industrial agriculture is very likely no longer tenable as the citizens of Cuba discovered during the 'special period'. So its not really a question of how am I going to make people do this stuff. It's a question of which path we're going to take in the world-changing transitions which lie ahead.

You'll also note that nuclear electricity cannot substitute for fossil fuels in fertiliser manufacture or even, in any straightforward way, for liquid fuels for tractors, trucks etc.

In terms of yield per hectare, all other things being equal and focussing on a single crop e.g. wheat or soybeans, the dry weight of food produced by commercial organic farming and industrial farming is roughly the same, only the former tends to improve the soil rather than wrecking it. See e.g. source1 source2

All other things aren't equal though. There are large further improvement in yield per hectare available, through focus on more efficient food systems. To pick an obvious example, feed-lot beef is an enormously inefficient way to produce food, as it relies on fattening cattle with plant materials (e.g. grains) which are edible by humans, with a resulting approximately 10:1 loss in the effective amount of food that results. That is, it's about 10x more efficient simply to make the grains into bread and feed it to humans, and limit the size of dairy herds to fit available grazing. (source: Pimentel "Food, Energy and Society")

When total food yield rather than single crop yield is considered, small (< 5 acre) farms do considerably better than larger ones in terms of yield per hectare. source

Typically these results are achieved by intercropping and similar methods, which means that if you compare wheat yields or something, the effect isn't visible. If you compare total dry weight food yields it's pretty clearly anything up to an order of magnitude better. Even better yields are achieved by approaches based on the french intensive method, a 19th century market gardening system. This is the basis for the Chadwick-Jeavons method mentioned above, and has claimed yields on the order of providing a complete human diet, plus necessary compost crops etc using something like 2000-4000 sq ft. source

The Cuban urban agriculture co-ops were getting these sort of yields too by the time they'd been going for four years. source

 

[rich!]

referring back to the Jeavons quote, is this the "How to Grow More Vegetables*" *than you ever thought possible on less land than you can imagine John Jeavons?

He's talking about reducing energy consumption to grow veg to 1% of existing levels!

30-60lb of courgette per hour of work (amortized, yes)


(yep, just got my copy back, forgotten what a book it is...)

 

[MikeMcc]

I've just been on a visit to the JET project at Culham (well worth a look if you can), whilst I was there I attended a meeting where the 'nuclear debate and the impact of the recent crises' was discussed. A few points came out that I wasn't aware of:

1. During the cold snap before Christmas the country came very, very close to exhausting it's reserves of gas. The Grain(?) storage facility had been nearly emptied whilst gas was dispatched to the continent (to fulfill present contracts), the MOD was warned that it was about to lose it's 'firm' supplies, as were power generating sites that have 'intermittent' supplies.

2. There is a major flaw with wind generation, you need to have a standby reserve of conventional generation capability in case of low or excessive windspeeds or high ice loadings (as is evident in winter, when the demand is highest). The example I was given was to imagine having 4 factories, but keeping one stopped but fully manned and maintained just in case one of the others stops production. At present there is no financial incentive for the generating companies to do this.

3. The project managers for the off-shore windfarm in the Thames Estuary accept that the project will NEVER break-even. The only incentive to get it built was to get carbon credits for the companies investing in it.

4. Offshore wind-farms (as they are currently planned) have major problems in maintenance and infrastructure costs. The idea of putting alternators at sea is actually a bit barking, but no-one is looking at other methods such as hydraulic transmission to shore generators.

Following the meeting we had a tour of the JET and MAST facilities. There are now projected time-lines looking at commercial fusion generators in 2040-2050. Unlike previous forecasts there is now a good understanding of the science and the engineering involved. JET has operated at a return of 65% compared to the power required to generate the fusion reaction. It is believed that it could be run at break-even given recently installed improvements. ITER is projected to have a return (gain or Q) of 10-20 times. MAST is looking at methods to simplify construction and use of fusion reactors and is progressing nicely

It terms of de-commissioning costs newer plants will have significantly lower costs. The main problems are due to activation of the materials in the reactor. The materials science has now progressed significantly, as examples, we now know to use low-cobalt, vanadium steel or low-oxygen copper.

 

[Backatcha Bandit]

2. There is a major flaw with wind generation, you need to have a standby reserve of conventional generation capability in case of low or excessive windspeeds or high ice loadings (as is evident in winter, when the demand is highest).

Mike, you might find this interesting:

http://www.dynamicdemand.co.uk/the_technology.htm

Dynamic demand control is a technology which can be incorporated into electrical appliances which enables them to provide important services to the power grid such as peak load management and second-to-second balancing of supply and demand.

Any electrical appliance that is time-flexible (in other words, is not too sensitive to when its energy is delivered) Could be used. These could include industrial or commercial air conditioners, water heaters an refrigeration. Thousands (and eventually millions) of such loads acting in aggregation to could provide an extremely simple and cost effective way of helping to manage the power grid.

Research is becoming available which indicates that an aggregation of such 'intelligent' loads could be extremely beneficial, for example, by smoothing out the minute-to-minute and hourly variations in demand on the grid. This would replace certain types of back-up generation and hence increase efficiency. In future, the technology could be used to smooth the supply from renewable power. This could theoretically allow a greater amount of renewables to be connected.

Very simple, yet effective idea to help deal with the 'episodic' nature of RE generation.