Domestic Solar versus Domestic Wind ? Solar wins, every time....

I still see people on eBay bidding hundreds of pounds for 300W domestic wind turbines.  Some of the sales sites use terms such as '..free energy...' and '...save money...'. but these claims simply don't stack up....

Given that you can buy 170W solar panels on eBay for around £80 or so each, let's do a very simple comparison based on real data from my own experimental installations of both solar and wind (see my previous posts for more details on each).

Since 300W is a common-enough domestic turbine rating (based on a 1.4 m blade sweep), we'll do the numbers based on 300W. 

Let's assume that whatever installation materials / batteries / controllers / inverters / instrumentation / cabling etc you'd need for one system would cost exactly the same as for the other.

Let's also assume that you've bought your 300W turbine on eBay for £160, the same price as two 170W panels.  To make it even simpler, we'll also de-rate these solar panels to a combined 300W watt-peak output.

Planting the bare-root hedging....

After a rapid thaw, in just a couple days, all the snow that had been hanging around for a few weeks disappeared and so we took the opportunity of the break in the weather to get our new hedge planted.

just a couple of days earlier....

We initially measured out the spacing with a marked length of timber (we've planted a double row at around 5 plants per metre), and then tried to sink the spade fully into the ground at each individual plant location.  Around 75% of them were fine, which meant we would just need to sink the spade to its full depth, wiggle it back and forth several times to make a rectangular slot, and then ease the roots of the plants down into position before closing back the soil using the heel of a welly.

an easy stretch, just used the spade to open up a slot.....

AIM Stocks – what to watch out for....

My own professional expertise covers one particular area of minerals and metals processing.  Note, however, that I'm not a financial adviser.... do your own research.

  

The Alternative Investment Market (AIM) is a UK market for shares in smaller, more risky companies.

You've spotted a start-up company that's reporting great things – they've recently floated on AIM to raise £100m and the financial press is full of its potential – and so you've also bought into the marketing spiel and you now own a fraction of this company – they either have a new production process that's going to revolutionise an industry sector or else they've specific oil, gas or mineral rights to a particular piece of land or sea and therefore everything looks rosy, yes ?  

Wrong ! 

Why ?  Read on....

So, this fantastic new company has, say, the oil or mineral rights to a particular piece of land or sea.  What does this mean ?

Well, it means exactly what it says.  The company has probably agreed to acquire the sole and exclusive rights to extract whatever mineral they specified from under this piece of land or sea, but usually only for a finite length of time to commence, i.e. some government or other has given them maybe five years to build a full-scale production operation, or at the very least to commence 'meaningful works' – if your company fails to meet this deadline, then this (very expensive) option lapses and is up for grabs again and anyone else can then bid for the future rights.

So, your AIM company with a market capitalisation of £100 million wants to develop, say, a mineral minesite. 

Dead easy, yes ? 

Wrong again !

Have you any idea of the sort of financial and regulatory frameworks with which it's required to comply, even in so-called third-world countries ? 

Firstly, there's the initial cost of acquiring the option, let's say a lowly £20m, then they may need to confirm that the resource is exactly as rich as it's claimed to be, maybe £2m in further testing etc, then there's a series of feasibility studies required, eventually up to a level that would be acceptable to future equity partners or lenders.  Let's say £1m in total as a ball-park figure.  Then there's an Environmental, Social and Impact Assessment study (ESIA) into the proposed development, let's say £500k and which may well be on the low side.  Then there's survey & planning fees, consultation with local residents, possible relocations, public relations etc, let's say another £1m just for starters, if you're very lucky.  

Homemade Axial Flux Generator - Part 1 - The Mechanics....

Late last year, I'd thought I'd have a go at building an experimental generator which could be used with a wind turbine, either a new-build Savonius vertical-axis type or else utilising my spare set of home-made blades for our existing horizontal-axis machine.     

I'm starting small, at only around 150 mm (6") overall rotor diameter but I've a couple of worn front brake discs lying around in the workshop from my old MGF (long gone now....) which could possibly be used for a larger version in the future.

After first looking around at what others have done on YouTube etc, I came up with a slightly different design to most of the others and then set to work.    At this stage it's intended to be a 3-phase alternator and so with 12 magnet poles we'll need 9 coils cutting the flux during rotation.  This will give the required 120 degrees of phase separation during operation - there's several animations available on the web which show moving graphs of the voltages induced in a 3-phase alternator.

The generator coils will be static, i.e. will form the 'stator', and the magnets are fixed to steel plates and rotate, i.e. the 'rotor'.  The assembled rotor comprises two parts, the outer and inner.  The rotor shaft rotates in ball-bearings in the housing, to which the stator will be fixed in position.

I bought a couple of profiled steel plates from eBay, for the rotor discs.   I already had several pieces of aluminium round and square bar in the workshop from which to machine the bearing housings and shafts etc.

bearing housing, temporary central bolt,
rear bearing, rear stub shaft and bearing spacer

There are two bearings fitted in the front of the housing, so the generator shaft can rotate independently, and a third at the rear which will support the direct connection of a turbine blade set via a stub shaft.   The entire blade hub / generator assembly could then be retained by a single M10 central bolt - I've just used a length of studding for the moment, turned down to 8 mm diameter at the rear end so I can fit into the cordless drill chuck for testing.

There's only one way to remove a tree stump....

With apologies to Jasper Carrot and his old '...there's only one way to kill a mole..' comedy routine....

We've five tree stumps on our new piece of land (all conifers) that are quite large and in a difficult spot for removal by digging, and I know from experience it's also back-breaking work exposing the stumps down to a level where the roots can be cut.  Hiring a stump grinder for a weekend also seems a very expensive option.

In anticipation of acquiring the land, we'd cut the trees down to just above ground level around 9 months ago (they'd already been cut to below head-height by someone else in the past) and then we killed them off using Bayer's chemical tree stump killer (glyophosate), which seems to have done the trick since there's been no new growth and the bark on the stumps has already started to soften and can be pulled off easily by hand.

Land acquired.....

It's been quite a while since I last posted, what with work commitments and Christmas etc, but some sort of celebrations are in order !   

Our purchase of additional land adjacent to our house went through in November of last year.  It's a strip of 5 metres width and around 35 metres in length.   We had first expressed an interest in buying this land back in February 2011, and so the whole process took around 20 months to complete....

We won't frighten you with the costs, but adding legal, survey and planning fees it came to an awful lot of money for a simple extension to the gardens.

Anyway, we've now got the land and are very pleased with it.  The neighbouring farmers also bought the remainder of the available land for sale, as additional grazing for their livestock.

So we've already taken down the existing fences and hedges, and hired a mini-digger and operator for a day to clear out one particular area which must have been used as a dumping ground for hedge and grass trimmings for the last forty years or so.

the northern end, before clearance.....

and after....

Some of our old hedge trunks were very substantial and so we've added to our stockpile of logs for the fire.   They need to season for about a year first though, to dry them out properly, so they'll be good for next winter.  The rest of the tree and hedge cuttings went on several bonfires.

Home-made Solar Panels - Part 2 - Operational Data, Costs & Economics

This is the promised second part of the Solar Panels post.  In this, we'll take a look at Operational Data, Costs & Economics.

Operational Data

The first panel was commissioned on 03 May and the fifth on 20 June.  Operational data was collected on a daily basis from the time the first panel was in place, and so at the time of writing we've exactly six months' worth of data. 

This summer has been very much a mixed bag in terms of weather - May wasn't too bad, June was very poor and the beginning of July only a little better, but since then it's been more typical of what we can generally expect around here.

Graph 1 below shows the total cumulative energy from the array since the time of hooking up the first panel.  The curve starts off rather shallowly and then gradually steepens as more panels become live, but the gradient is not as high as expected since the weather worsened through the commissioning period.  

Note that all of these graphs shown here represent net AC energy provided to the house grid, i.e. all the losses and inefficiencies in the grid-tie inverter during rectification and transformation from DC to 240V AC are already accounted for.  The light red line on the graph is a linear trend line.



Graph 1

(click on any of the figures for a larger image)