Investigating the embodied energy of the EmonPi & OSCEDays London 12-14th June.

On the 12th – 14th of June there is an event happening called Open Source Circular Economy Days in many cities around the world, including in London https://oscedays.org/london/ which we will be attending. I first found out about the event from Lars Zimmerman who is on the core organising team and I met last year at OuiShare, Lars runs http://openitagency.eu encouraging and helping people incorporate open source in their businesses, organisations and projects. The aim of Open Source Circular Economy Days is to bring open source thinking to the circular economy. The energy associated with manufacturing is a large part of our overall energy consumption and the question of embodied energy especially in the zero carbon energy sector is particularly important to understand better. There is quite a bit of discussion at the moment about the level of energy return on energy invested EROI required from the zero carbon energy sector as a whole in order to sustain a certain level of technological society.

My impression of trying to look into embodied energy and life cycle analysis is that it seems that the measurement of embodied energy and other impacts associated with manufacturing our stuff and then the understanding of what solutions are available to reduce this embodied energy, especially in electronics is still in its infancy compared with other energy demands that we are more familiar with like the solutions available for space heating and transport, both of which have solutions that can achieve 70-90% energy reductions without reducing the level of comfort or distance travelled http://openenergymonitor.org/emon/sustainable-energy.

We're particular conscious of this question at OpenEnergyMonitor as we get our hardware manufactured and see the quantity of stuff involved in the production of our equipment. It has always been interesting to read about developments from other projects and companies who have been looking at this for sometime but in different fields predominantly outdoor clothing: http://www.patagonia.com/us/footprint and http://www.howies.co.uk. They have often achieved quite substantial improvements by looking at their materials, and supply chains in detail.

With Open Source Circular Economy Days coming up and after talking to Erica Purvis of http://technicalnature.org.uk/ who is one of the organisers of the London even we decided to try and sketch out a draft initial analysis of the embodied energy associated with the emonpi to take along with us. I emphasised its initial status there because I don’t have a high confidence in the reliability  of the data at the moment but I think it does provide a useful start on which further detailed research can be done.

Embodied Energy Audit Process

With a little research I found an example of an embodied energy analysis for an LED light with an accompanying dataset for the embodied energy of different components here: http://users.humboldt.edu/arne/Alstone_etal_Lumina-TR9-Embodied-Energy_Jan11.pdf this example referenced data from the European commission project  Eco-design of energy-using products: http://ec.europa.eu/enterprise/policies/sustainable-business/ecodesign/methodology/files/eup_ecoreport_v5_en.xls.

I then calculated an estimate for embodied energy by using the embodied energy dataset from these two sources and a detailed list of components for the emonpi including the weight of each component. The spreadsheet with the calculation can be downloaded here on the EmonPI open hardware github repository:

https://github.com/openenergymonitor/Hardware/raw/master/emonPi/emonPi_V1_5/emonpi_embodiedenergy.ods

here's a screenshot of what it looks like:



I have summarised the main results in these two graphics:

Interestingly the application of the embodied energy values in the dataset suggest that at least for the parts that we are most involved in the custom design of (The EmonPi Shield and the aluminium enclosure) the embodied energy is dominated first by the enclosure at 10.1 kWh and then by the manufacturing of the printed circuit board (2.2 kWh) and the assembly of the unit (1.6 kWh). The integrated circuits only account for a relatively small percentage at 0.2 kWh.

Aluminium enclosures
The estimate for the embodied energy of the aluminium enclosure is based on the 40 kWh/kg figure in Sustainable Energy without the hot air. This equates to 144 MJ/kg which is lower than a couple of other figures I could find for standard aluminium embodied energy. The Wikipedia figure is 155MJ/kg and is based on a 33% recycling rate. The figures I could find for the embodied energy for aluminium from bauxite where between 191MJ/kg and 342MJ/kg. The enclosure made from aluminium from bauxite could at the higher end use 24 kWh and at the lower end require 16 kWh. 100% Recycled aluminium however only requires between 11.35MJ/kg and 17MJ/kg. The EmonPi manufactured from 100% recycled aluminium would therefore only need between 0.9 - 1.3 kWh to manufacture. The EmonTH ABS plastic case is about a third of the size of the EmonPI case and weighs 32g it had an embodied energy of around 1.0 kWh (111MJ/kg). A plastic EmonPi case might weight about 3x this (~90 grams) and so may use around 3.0 kWh. The aluminium would need have been recycled around 7-8 times to achieve the same level of embodied energy as an ABS plastic enclosure. There are also lower embodied energy plastics available such as Polypropylene (64-94MJ/kg) and recycled PET  may use around 42-55MJ/kg and then perhaps there are even more options in the design of enclosures to minimise the amount of material used.

Manufacture of printed circuit boards and assembly

Beyond learning more about enclosure options it would be useful to focus on getting a better idea for the reliability of the data for printed circuit board manufacturing and assembly and what options exist to lower their embodied energy requirements.

OSCEDays
If your interested in learning more about the Open Source Circular Economy days event or joining us at the event in London have a look at the event pages here:
https://oscedays.org
https://oscedays.org/london

Useful links and references:


Introducing emonTH V1.5

The emonTH Temperature and Humidity wireless sensing room node is back in stock in the shop today with an updated version to V1.5.

http://shop.openenergymonitor.com/emonth-433mhz-temperature-humidity-node/

V1.5 is a minor hardware update adds support for RFM69CW radio and includes a DIP -switch which allows setting four RF node ID's (19-22) easily and quickly. See emonTH wiki for updated documentation

emonTH V1.5 with DT22 Temperature and Humidity Sensor
emonTH V1.5 with RF node ID DIP switch and RFM69CW
















emonPi Vs emonTx V3 Comparison

Here's a quick comparison table comparing the emonPi (currently active on Kickstarter!) to our existing emonTx V3 energy monitoring unit:

emonPi
emonTx V3


It is no secret that there is much similarity between the two units, both are cut from the same cloth. Both units use the same ATmega328 Arduino IDE compatible microcontroller and front-end CT channel signal processing which gives identical monitoring accuracy. 

The emonPi is most suitable over the emonTx V3 for home or small business whole circuit energy monitoring and also solar PV where Ethernet or WIFI can reach the consumer unit. Being a one-box-solution and with its status LCD the emonPi is quick and simple to install and maintain. 

For larger systems where there could be multiple transmitter nodes and more channels to be monitored the emonTx V3 could be most suitable. The emonTx V3 transmits it's readings via RF (433Mhz) to an emonBase web-connected base station (Raspberry Pi + RFM69Pi). Multiple emonTx V3's can be used with a single emonBase

The emonTx V3 has the edge over the emonPi when it comes to powering the unit, the emonTx V3 can be powered directly from the AC-AC adapter while also taking an AC voltage waveform sample. Due to the higher power requirements of the Raspberry Pi the emonPi requires an additional 5V DC USB adapter. 

Struggling to decide? It's also worth noting that the emonPi and emonTx V3 can work together. emonPi by default also functions as an emonBase; as well as local monitoring the emonPi can receive data via RF from multiple emonTx V3 and other remote nodes such as emonTH temperature and humidity room node. 

For further details of the units see the Technical Wiki documentation pages.



Introducing emonPi: Raspberry Pi based energy monitor



emonPi Raspberry Pi based energy monitor Kickstarter

It's an exciting time for us; this week (on the 1st April, unfortunate timing!) we launched a Kickstarter crowd funding campaign for our emonPi Raspberry Pi based energy monitoring unit

The emonPi has been in development for the past 12 months or so, if you have been lurking on the forums you have probably seen activity on the emonPi's open development forum thread. Thank you everyone who contributed. 

The emonPi has been developed with input from the community, merging the monitoring unit and web-connected base station into a single easy to install and setup energy monitoring solution. 

The emonPi is fully open source hardware and software. It's been designed for maximum hackability and customisation being built on a fusion of two popular open source hardware platforms Arduino and Raspberry Pi.

emonPi Technical Features 

  • Two channel CT monitoring with AC sample input 
  • Compatible with Raspberry Pi model A, model B, model B+ and Pi 2 
  • Arduino compatible ATmega328 with ability to remotely upload sketches vis Raspberry Pi Serial 
  • RJ45 DS18B20 on-wire temperature bus to allow many temperature sensors to easily be added using a RJ45 breakout board for heat pump monitoring applications 
  • PWM and IRQ I/O's on RJ45 
  • Status LCD with function push button
  • Raspberry Pi shutdown button
  • RFM12B / RFM69CW with SMA antenna to receive or transmit data from other sensor nodes
  • Option to add OOK (on-off keying) transmitter footprint for controlling remote plugs etc. 
  • Option to add EEPROM to enable Raspberry Pi HAT compatibility (please get in contact if you have experience setting up Linux device tree). 
  • Open-source hardware, firmware and software 
  • High quality custom made, wall mountable enclosure
See the emonPi wiki for more technical info (currently under development).





We had fun filming a Kickstarter promo video, demonstrating some applications of the emonPi, Emoncms and the OpenEnergyMonitor system installed around where we are based in the mountain of North Wales, UK.  


Here's a video showing the emonPi installed and talking through how setup will work in practice. Having the LCD to show local IP address, status and uptime etc will no doubt make the system much more user friendly and accessible. 



The Kickstarter will be running until Apr 20 2015 9:46 PM BST, if we haven't reach our funding goal by then we will get nothing! Please help us share and spread the word :-)

Please help us by sharing our Kickstarter page with interested parties

We believe the opportunities and benefits of taking an open-source approach to smart monitoring and control challenges are significant; we hope to encourage others to start projects & businesses that also work towards a zero carbon future in an open way. 


Energy Display Options...

Sadly as of last week we have run out of emonGLCD kits in the shop and have decided to discontinue the emonGLCD for the moment. Preparing the through-hole kits is very labour intensive and the time and skill required to solder assemble is lagging behind our other pre-assembled SMT units.

Work has begun on a SMT pre-assembled replacement (see forum thread). However this would probably require significant investment in injection moulding tooling and commitment to high volume production. This would not would be a problem if we were sure on the design. However, I'm not sure if a standalone display is the right avenue to go down...

I am aware there that there is certainly value in an 'always on' wall mount / coffee table energy display. Being able to easily glance at the display throughout the day when your home really does remind me to switch off lights and appliances when not in use. As well as checking everything is turned off (base level energy consumption) when leaving the house. An always on display gives users a 'feel' for how much energy various devices use as the display increases or decreases in real-time as a device is switched on or turned off.

The future is mobile, everyone has at least one mobile device and increasingly as these devices are upgraded there are a large number of perfectly working just a bit slow older devices which could easily be given a second life as an energy display. This could help reduce the number of devices which end up being recycled or worse put into landfill, therefore helping to save energy in more ways the one! Old second hand android phones or tablets can be picked up on Ebay for less than we could make an emonGLCD!

I recently repurposed an old Nexus 7 tablet (2012 model) with a cracked screen as a home energy display displaying Emoncms MyElectric. I installed an app to keep the screen on all the time when plugged in charging. The tablet uses 5W of power. An added advantage of using a mobile device as an energy display is they are 'mobile'! The display can easily be moved around the house to support investigation power consumption of various appliances.

Much work could be done on the software side to make a really nice packaged android app for Emoncms which would support an energy display mode, useful features might be:

  • Intelligent screen-on-off e.g the display could turn off at night, when energy falls to base level consumption indicating the house is unoccupied 
  • Using the tablets motion / proximity / light sensor to sense movement to turn screen on-off
  • If device has an AMOLED display only certain pixels could be lit up to save power, like on the Moto-x Active Display 
  • Auto start at startup and full screen mode 
  • Home screen widget to be used if user does not want to decicate a devices solely as an energy display or to be placed on current mobile home screen to enable quick checking of power consumption / temperature etc when out and about.    


Emoncms MyElectric on Nexus 7 with cracked screen

A super low power alternative could be to use an old e-reader with an E-ink display. Here's Emoncms MyElectric running on a hacked Nook Touch.

Emoncms MyElectric on Nook Touch
Head over to the forums and let us know what you think...

Real World emonTH Battery Life




The battery on my home emonTH Temperature & Humidity Node has just died for the second time in 14 months. Each set of batteries lasted exactly 221 days (7 months and 9 days)! The 2 x AA alkaline battery voltage started at 3.1V and the emonTH stopped working just after the voltage dropped below 1.2V (final dying breath was at a battery voltage of 0.8V!).  The two AA batteries installed were low cost alkaline batteries unbranded from e-spares. Battery life would not doubt be longer from some quality cells. 

I recommend using rechargeable alkaline batteries if possible in the emonTH, for least environmental impact. See my previous posts on emonTH battery selection and power consumption optimisation

My emonTH had a DHT22 temperature and humidity sensor connected and was set to the default post rate of one minute in-between samples. The unit was running V1.0 firmware (the firmware is now at V1.2, there have been a couple of minor battery life improvements). 

It's very impressive how the DC-DC boost converter onboard the emonTH continues to boost the depleting battery voltage to 3.3V, using this method allows the battery to be drained much further than powering the unit directly. 






RFM69CW Power Consumption

Following on from my post on RFM12B power consumption here's the same measurements for the RFM69CW (see RFM69CW intro blog post).

Current consumption was measured in the same way as explained in the RFM12B post back in July 2013. Voltage drop was measured across 10R current shunt resistor.

A fully populated emonTx V3.4 with a 433Mhz RFM69CW running discrete sampling code with a single CT connected was used in the test. The V3.4 was powered directly with 3.3V DC from bench PSU.

emonTx V3.4 with RFM69CW Test Setup

Test setup illustration


Test Bench
Please excuse my photos of the scope traces rather than screen captures, for some reason the USB socket on the scope did not seem to be working today :-(

Full sample and RFM69CW transmit trace capture

When an AC-AC adapter is not connected the emonTx goes to sleep in between readings. The above current trace shows the ATmega328 waking up for 295ms to sample from one CT channel the spike at the end is the RFM69CW transmitting. The trace below is a zoomed in capture of the RFM69CW transmission and LED. 

RFM69CW transmission current consumption 
The current trace above shows the RFM69CW transmission: 33mA @ 3.3V (109mW) for 4ms. The current spike at the end (up to 39mA) is the emonTx LED. In this test the emonTx was running the standard discrete sampling firmware transmitting a JeeLib packet structure with six integers. Since we were only sampling from one CT four out of the five integers will be zero. 

This equates to a 15 bytes payload plus 9 byte overhead @ 48kb/s. See JeeLib packet structure


In comparison I measured the RFM12B to consume 25.5mA @ 3.3V (84.2mW) for 3ms.

My measurements pretty much agree with the datasheets, here's a comparison table compiled by Low Power Labs:


Even though the RFM69CW does consume more power while it's transmitting it does have a lower sleep consumption than the RFM12B. This increased transmission power should result in an increased transmission range.

I've started a forum thread for discussion: http://openenergymonitor.org/emon/node/10210

Introducing RFM69Pi V3 Raspberry Pi Expansion Board


RFM69Pi on Raspberry Pi B+, also compatible with Raspberry Pi Model B and Pi2

RFM69Pi - just like RFM12Pi but with upgraded radio and more I/O available




The RFM69Pi is a minor update to the popular RFM12Pi Raspberry Pi Expansion board. It adds support for the RFM69CW RF module as well as breaking out as much I/O as possible from the ATmega328 to open up the options for greater connectivity and compatibility. The RFM69Pi was developed with help and inspiration from Nanode RF designer Ken Boak, together we are working on a relay heating controller board using the RFM69Pi. 

The RFM69CW is backward compatible with RFM12B, see blog post introducing the module. From an end user's perspective there should be no difference when using the RFM69Pi over the RF12Pi apart from a new input called RSSI (Received Signal Strength Indication) appearing in Emoncms. 

You must be running the latest pre-build SD card image emonSD-26-02-15.img (now shipping) or emonHub must be updated manually to the latest Development branch version to enabled auto detection of the faster baud rate used by the RFM69Pi (38400 as opposed to 9600 on the RFM12Pi), and RSSI value handling. 

If you're running pre-built SD card image emonSD-13-08-14.img or earlier then emonHub can be updated by running:

$ sudo service emonhub stop

$ cd emonhub

$ git pull 

$ sudo service emonhub start 

check log for errors 

$ tail /var/log/emonhub/emonhub.log


The RFM69Pi is now shipping from our online shop
http://shop.openenergymonitor.com/base-stations/

RFM69Pi Technical Docs Wiki Page:
http://wiki.openenergymonitor.org/index.php?title=RFM69Pi_V3

Open-Source Hardware Design:
https://github.com/openenergymonitor/Hardware/tree/master/RFM2Pi/board/RFM69Pi_V3.1

RFM69Pi Default Firmware:
https://github.com/openenergymonitor/RFM2Pi/tree/master/firmware/RFM69CW_RF_Demo_ATmega328

An open source hourly zero carbon energy system model

I've been doing some work recently with Philip James from the Centre for Alternative Technology on developing a set of open source zero carbon energy system models based on ZeroCarbonBritain that visualise in a javascript based web page application how energy demand can be supplied by a variable renewable energy supply using a mix of storage technologies. You can create your own scenarios, choosing how much wind, solar, storage technologies etc are used.

Its still work in progress but the models we have built so far are now online and can be explored here:
http://zerocarbonbritain.org/energy_model


The source code is all available there too as well as the original ZeroCarbonBritain spreadsheet model: https://github.com/philJam/energymodel

Visualising hourly surplus and shortfall:


Visualising battery, hydrogen, synthetic liquid and gas store levels:


This builds partly on findings and questions raised from our earlier work on the Snowdonia household energy study: here;http://openenergymonitor.blogspot.co.uk/2014/11/snowdonia-household-energy-study.html


The aim will be to extend that analysis to look at the amount of renewable energy and energy storage required to supply the energy demand after implementing measures like building insulation/retrofit, heatpumps and electric transport.


I find it very interesting looking at how all of these different elements can come together to create a zero carbon energy system, to understand better the relevance of different solutions. With a framework like this it becomes more possible to put ideas like smart electric car charging or excess pv diversion to immersion heaters and battery stores in context, to get a better idea of actually how much effect different solutions can have.

Pre-built heatpump dashboards

I've been experimenting with the idea of a pre-built heatpump dashboard - a bit like the myelectric module for home energy monitoring.

The initial concept is up on emoncms.org under the Extras > heatpump tab. The heatpump fan turns in relation to power input a bit like the winderful windturbine.

Configuration is by naming convention at the moment, the dashboard looks automatically for feeds named or containing the words: heatpump_power, heatpump_kwh, heatpump_flow_temp, heatpump_return_temp, ambient_temp and room_temp, using these if present.

 

Next I plan to extend this for heatpump monitors that also monitor either flow rate or heat output in order to show COP information including a daily power input/ heat output bar graph below the heatpump graphic.

I've been doing this work with John Cantor who is using the OpenEnergyMonitor system for heatpump monitoring.

The source code for this can be found here if youd like to try it on your own install, just drop the folder heatpump into your emoncms modules directory: https://github.com/emoncms/development/tree/master/Modules/heatpump