Deleted 2 December 2022 at 10:39PM edited 12 January at 11:53PM in Green & ethical MoneySaving 31 replies 916 views

ispookie666

Does anyone know if domestic biogas is a possibility in UK?  

zeupater

ispookie666 said:

Does anyone know if domestic biogas is a possibility in UK?  

Hi

It's down to scale & how much you want to invest ...

I know someone that used a biodigester on waste slurry and used the low pressure gas for various things around the farm ... it was only classified as a small system, but in a domestic environment as opposed to being scaled against a couple of old barns would look absolutely huge .... unless you've got a free and readily available supply of waste to feed the system combined with many acres to fertilise with the left over solids then as a money saving project it's probably a non-starter ... and that's before the planning department get involved (sound, smell, hazard etc) ..

I suppose community scale projects in semi-rural areas would be a better targetted approach, but that introduces the complexity of distribution and associated added costs ...

HTH - Z

70sbudgie

Several years ago I came across a development where they were trialling domestic micro CHP. I don't know what happened to the trial, or how widespread these would be now, or even whether it would be possible to convert one to biomass (or if there is a biomass option). 

Another thought I had was for low level generation. You've used figures of kWhrs requirement over winter, but how does that translate into instantaneous power (for you, I don't mean the calculation)? For example, if your base load as described above is 350W, with batteries to store your excess intermittent generation you may be very comfortable with a micro generator of 250W. At this scale, micro hydro (or a CHP) might be more within reach. 

If you could size your micro generator to be slightly above your very lowest power requirement, when you are not using that energy, it would be trickle charging your batteries. The challenge would be to find that sweet spot that is the minimum generation that charges your batteries enough. Then you can look for an appropriate generator. 

I have read threads on these boards, which weren't dis similar, but confusion around units obscured the discussion.

I would love to go off grid, but my family is too far removed from the possibility right now. But that doesn't stop me trying to work out how I might do it.

In my head, the logic process goes something like: what are my minimum and maximum instantaneous power requirements? What are the time requirements associated with each (ie how much of the time at min and how often do I need max). This then would give me an idea of total energy required (a usage profile). Then the challenge becomes matching generation and storage to this. Not forgetting thermal storage for domestic hot water and heating, where a "trickle charge" is commony used to offset demand and generation. (My concrete floor with wet UFH is a good example - heating it in the morning is enough to keep the room warm all day).

70sbudgie

It is interesting that a special feature is that it is portable. I wonder how that would effect planning.

I mentioned the micro CHP as I wondered if that might be a way to generate electricity from your existing wood burning. Especially as you mentioned the potential for a second wood burner. Installing a biomass micro CHP instead of that second wood burner, may give you a low level winter electricity generator.

Edit to add, they might actually be called nano CHP.

Karmacat

scarter, I've subscribed to your thread - I love your thinking!  I don't have any information for you right now, but I really admire what you're trying to do.  Have you looked at products carried by the Centre for Alternative Technology in Wales?  Or they also work really hard on downsizing energy needs, as you're saying.  

Wonderful stuff 🌈

zeupater

Deleted_User said:

[...]
I think a wind turbine like this would be enough (if they worked reliably for at least a few years - which I very much doubt):

https://www.amazon.co.uk/Turbine-Generator-Windmill-Controller-Homeuse/dp/B09D76GHS2/ref=sr_1_13?crid=23JZ3NUGK7SYC&keywords=wind+turbine&qid=1670147091&sprefix=wind+turbine,aps,88&sr=8-13&th=1

[...]

Hi

You also need to consider the physics, surroundings & wind speed profile for your location ...

A turbine rated at 800W would be at a given wind speed (Spec 13m/s), half that wind speed (6.5m/s) and the output drops to 100W, half it again (~3m/s )and it's 12.5W, do it again (1.5m/s) and it's marginal whether the embedded energy would be enough to start the blades spinning (Spec 1.3m/s).

With standard HAWT you'll find that any ground obstacles within hundreds of metres will create turbulent airflow that affects performance, the turbine itself will spend much of the time searching for airflow direction and therefore less time generating ... the only way around this is to go higher, the problem in an attempt to get above the turbulence, usually then impeding on planning restrictions (maximum height / ratio of height:distance to boundary .. etc).

West Scotland generally has decent average wind speeds compared to most, at ~5-8m/s it's probably about double that of the majority of the UK, however, it's still an average including the 60+mph periods, and don't miss the point that the spec of the referenced turbine state that the unit isn't expected to survive gusts of >40m/s, so around 90mph, so you'll need to keep a close eye on the forecasts and be able/ready/willing to lower the mast/turbine to protect your investment ....

Alternatives to look at for an urban environment would probably include VAWTs, they're generally not as efficient as HAWTs in laminar airflow, but as they're also not as affected by turbulent airflow they can be operated to some degree in most garden environments ... problems then revolve around quality of build relative to unequal forces on the bearings etc and how this affects the lifespan/maintenance schedule ....   

HTH - Z

chris_n

Do you actually need a fridge in winter in Scotland? Is there not a possibility of a cold larder, that's what my Grandmother had. My crate of beer is outside ready to drink!
If you don't mind a bit of exercise how about a pedal generator ;-)

chris_n

Deleted_User said:

chris_n said:

Do you actually need a fridge in winter in Scotland? Is there not a possibility of a cold larder, that's what my Grandmother had. My crate of beer is outside ready to drink!
If you don't mind a bit of exercise how about a pedal generator ;-)

We probably don't need a fridge. I'm just unsure/inexperienced about storing my home grown veg etc over winter. I also have my seed potatoes for next year in the fridge!

But what I'm reluctant to give up are the big freezers as that lets us stock up on cheap food and also store more of our summer veg harvest.

We don't mind exercise at all - we have both indoor and outdoor home gyms. I would love the idea of a pedal generator but hubby insists it's not worth it - you'd get nothing worthwhile out of it. 

A pedal generator was a bit of a joke really, what you would actually get out of it would be around 100w maybe 150 when you have done it for a year. I don't know anything about storing veg but if you ask in the old style and / or the greenfingered thread I'm sure you will get some help.

70sbudgie

I saw an advert for a modern cold store. Basically a ventilated underground shed. I loved the idea until I saw how big and expensive it is. That was refrigeration prior to electricity.

Edit to add: CHP = combined heat and power. They are most often industrial gas plants, used where there is also an onsite demand for steam. But the potential for domestic use, is huge. Especially if it can use an alternative fuel to gas.

Karmacat

One thing that's a possibility is a heat pump?  Air source (cheaper, bit less efficient) or ground source (upends the house and garden for weeks).  Air source might be good enough, as you're not looking to provide for all your needs, just that "gap".