Energy Saving

[robgul]

Last week, I had a smart meter fitted. It came with a 'smart' monitor that shows me how much is being used at any one time. I have separate fridge and freezer and obviously they need to be on all the time. I wondered just how much that cost and the monitor shows me that they run at about 1p per hour. Sometimes the display shows 1p per hour for both and sometimes even 0p, I guess when they're at their optimum temperature and therefore aren't drawing any power. The (new) kettle, is about 25p per minute and the toaster a whopping 46p per minute. The oven is quite interesting in that it draws c43p when heating up but next to nothing when at temperature. I had always assumed that when switched on, things like ovens and fridges drew power constantly. And the washing machine was a pleasant surprise at about 1p per hour throughout a three hour cycle.

I still don't see how they save me money as I still need to turn these appliances on in order to use them. Hopefully they will insofar as not having to pay the wildly inaccurate guesstimates utilities companies come up with. Between end of January this year and end of July, I received two refunds totalling over £400.

Take the readings on the SMART monitor with a large pinch of salt - they are notoriously unreliable.

We had one in our previous house for a couple of years and have one at this house since June - I did get a bit concerned when we were allegedly burning gas at the rate of £35,000.00 per hour (yes, 35 thousand quid) - and the electricity side shows no consumption when a tumble drier and bread machine were running. It does tell you what time it is though!

"Saving money with Smart meters" simply isn't true - the saving is that being aware of the consumption it frightens you and you switch stuff off. The ONLY upside I can see is that the meter readings go to the supplier (our billing matches the readings I take each month) for billing.

 

[Lonsdale73]

Assuming you're paying 25p per kWh and your kettle is 3kWh (which is a big kettle) it would use 1.25p per minute

You know, I'd never really given any thought to the power of a kettle so I've just checked the label and it says 2250-3000w. I'm not entirely convinced as to how accurate they are so not taking the readings too seriously. For example, at 7am it said I had used 40p for the day so I want to know who broke in while I was tucked up in bed and stole some watts!

 

[Lonsdale73]

Take the readings on the SMART monitor with a large pinch of salt - they are notoriously unreliable.

We had one in our previous house for a couple of years and have one at this house since June - I did get a bit concerned when we were allegedly burning gas at the rate of £35,000.00 per hour (yes, 35 thousand quid) - and the electricity side shows no consumption when a tumble drier and bread machine were running. It does tell you what time it is though!

"Saving money with Smart meters" simply isn't true - the saving is that being aware of the consumption it frightens you and you switch stuff off. The ONLY upside I can see is that the meter readings go to the supplier (our billing matches the readings I take each month) for billing.

It saves the utility companies as they no longer employ meter readers. I've been querying this assertion for years and never had a straight answer from any company on the subject. I've only had this one fitted as I've not long moved in and the previous owner faced a £70k gas bill for a house that had stood empty for a few months through the better part of summer! So far lectric only as engineer took one look at the gas meter and stated it was above his pay grade to even contemplate tackling it. He did say it was still possible to bypass them and in my neighbourhood the going rate for this service is £50.

 

[Donald Sinclair]

Having a digestive biscuit with your tea will further reduce your iron stores.

 

[baldkev]

Having a digestive biscuit with your tea will further reduce your iron stores.

Eh?
It'll reduce the change in your pocket i guess.... what about chocolate digestives?

 

[Droogs]

@baldkev I think Donald's post was in answer to mine about tea helping lower my iron intake. Re Choccy Ds sadly no, too much sugar

 

[Phil Pascoe]

. He did say it was still possible to bypass them and in my neighbourhood the going rate for this service is £50.

I read the other day that there is more electricity stolen in one Indian State than all but eight of the highest consuming Countries in the world use.

 

[Ozi]

I have found my smart meter both accurate and useful. I can see at a glance when my kids have left their rooms switched on and that's hundreds of Watts, it even tells me who's awake as each consume different (excessive) amounts, it's prompted me to change all our lights to LED. Sad but I enjoy turning something unnecessary off that I wouldn't have known about when it's been left on and seeing the current usage light go from orange to green.

 

[Dave Moore]

Not quite right. It is at best ~60% efficient. In the combined cycle mode, the new “H class” Gas turbines with a triple pressure HRSG (heat recovery steam generator) and steam turbine can run at 60 % efficiency at ISO conditions. (Source: www.brighthubengineering.com among many others). Older plants in the simple cycle mode, only Gas turbines running, have an efficiency of 32 % to 38 %.

Coal-fired plants are in the range 32% to 42% (same source).

An improvement would be combined heat & power production (CHP) where the heat wasted by a conventional plant in heating the cooling towers is used to heat a local town or for local industry. Overall CHP efficiencies for gas turbines are typically in the range of 65% to 70%, although higher efficiencies can be achieved depending on site specific conditions and engineering design configurations. (Source: US Dept of energy).

Here in Finland where I live CHP efficiencies are typically higher. For example, burning 100 MJ fuel in a CHP plant generates 36 MJe usable electricity and 51 MJ heat. (Source: cleanfi.fi). Other plants achieve over 90% efficiency (Source: power-technology.com).

CHP is all but unknown in the UK I believe. If it raised power plant efficiency from 60% (absolute best at the moment) to 80% (comfortably below the efficiencies already reached by CHP) its adoption could have a really significant effect. The EU has estimated that District Heating and Cooling (DHC) alone could reduce European CO2 emissions by nearly 10% using mainly renewable sources and industrial waste heat. (Source: power-technology.com). Once again, the barrier is the up-front infrastructure costs.

Hi,
There are lots of CHP gas stations in the uk and I ve worked on the building of some. In fact ones that were built over 25 yrs ago and at end of life. The waste heat is used differently as it heats a waste heat boiler that drives a steam turbine generator as well as the gas turbine. Only problem is you cannot switch these on or off like you can with simply a gas turbine. Gas turbines as individual generators have been built at Lincoln (it’s now owned by Siemens) for around 50 years at least and exported all over the world. The newer gas stations are a newer design and I believe are recycling the turbine waste heat differently.
Regards,
Dave

 

[Just4Fun]

There are lots of CHP gas stations in the uk and I ve worked on the building of some. In fact ones that were built over 25 yrs ago and at end of life. The waste heat is used differently as it heats a waste heat boiler that drives a steam turbine generator as well as the gas turbine.

Do you regard that as CHP or waste heat recovery? I view it as the latter if it is using heat that would otherwise be wasted. By contrast, CHP sets out to produce both heat and power. (In that sense my explanation was not really clear.) So CHP relies on a synergy between heat production and power production so that both are more efficient than they would be on their own.

The heat produced is typically used for district heating schemes, so individual homes, businesses etc do not have their own heaters they just connect to the district heating system to tap the heat from the power plant. The heat can also be provided to industry in the form of steam. One recently-completed (2017) unit here produces 146 MW of electricity and 250 MW of heat and 50 MW steam, at 92% efficiency. I assume that it takes over from easiler units on the same site (that I am more familiar with) and the steam is mainly piped to a factory about 10 km away. Is there anything like that in the UK? Are there many district heating systems?

 

[baldkev]

@baldkev I think Donald's post was in answer to mine about tea helping lower my iron intake. Re Choccy Ds sadly no, too much sugar

Ahh, that makes more sense

 

[baldkev]

Do you regard that as CHP or waste heat recovery? I view it as the latter if it is using heat that would otherwise be wasted. By contrast, CHP sets out to produce both heat and power. (In that sense my explanation was not really clear.) So CHP relies on a synergy between heat production and power production so that both are more efficient than they would be on their own.

The heat produced is typically used for district heating schemes, so individual homes, businesses etc do not have their own heaters they just connect to the district heating system to tap the heat from the power plant. The heat can also be provided to industry in the form of steam. One recently-completed (2017) unit here produces 146 MW of electricity and 250 MW of heat and 50 MW steam, at 92% efficiency. I assume that it takes over from easiler units on the same site (that I am more familiar with) and the steam is mainly piped to a factory about 10 km away. Is there anything like that in the UK? Are there many district heating systems?

Yarp.....
https://www.viridor.co.uk/who-we-ar...or-new-carbon-emission-reducing-heat-network/
Its about an hour from me

 

[Woody2Shoes]

I can see no reason why new builds are not mandated to be at the highest possible level of energy efficiency. It will increase costs, but the absence of legislation is wholly down to the success of housebuilders in lobbying government in pursuit of profit.

The car industry - ICE sales banned from 2030, and gas boiler manufacturers - market shrinking quickly post 2035 are evidence of the ability of government to act when they want to.

Currently gas and electricity serve two fundamental purposes. Somewhat simplisticaly, gas can only provide heat, electricity can provde all energy needs - heat and light.

Generating electricity from gas creates losses, as do all energy conversion processes. It is typically ~60% efficient. Burning gas in a domestic boiler is ~90% efficient. Measured on a cost per KWH basis electricity will always be more expensive than gas unless the distribution costs are markedly different.

I agree about the house builders, I think they've got away with murder for far too long. I think you're overstating the government's power/determination with respect to phasing out ICE cars - the industry is making the change (and some of the old, particularly US, big names will disappear to be replaced by Chinese ones). I see a move to domestic ASHPs as potentially fraught - especially if we don't make much better progress de-carbonising our grid.

 

[Ozi]

https://www.bbc.co.uk/news/av/science-environment-59238305
Saw this today, thought you might be interested. The big difference of course is that for these people it was a step forward but a lot of us are going to have to think about rationing power consumption.

On the subject of CHP Jaguar and Aston Martin use this on their Gaydon site.