Energy monitoring at the Center for Alternative Technology - part 2

continuing from part 1:

The micro grid display

Enter Carlos!

Carlos has been developing the public energy display for the microgrid, so that visitors at CAT can see exactly how much energy all the renewable generators are producing and how much CAT is using. The display has a load of good features: graphs, statistics, comparison bars and other relevant info. Here's a screen of the total generation page of his display:

The display is programmed in php, and the interface between the database and the display is done via a script that creates an xml file and jpg graphs from data in the database and then a second script that fetches the jpgs and xml file and displays the output.

Carlos is very much an open source fan an we have been having some great discussions about were this open source energy monitoring and energy visualisation displays could go, we have some exiting plans in the works that I will come back to soon...

First a bit more about the current system in part 3...

Energy monitoring at the Center for Alternative Technology - part 1

Over the last two months I have been doing a project at the Center for Alternative Technology (CAT). I have been working on the monitoring system for the microgrid they have there, its has been and continues to be a really fascinating and enjoyable project.

CAT is one of Europe's leading sustainability center's, it is a university, a visitors center a pulisher of books, reports such as zerocarbonbritain and a place were practical solutions, sustainable technologies are tried out, tested and demonstrated.

For a sustainable technology enthusiast like myself it is a great place to be. There is a lot of green technology there! A very large PV roof, several hydro turbines, wind turbines, woodchip and pellet boilers, CHP plant, heat pumps and many others I'm sure I have missed. The electrical generation technologies are all connected up to a microgrid and there is a heat main on the heating side of things.

The microgrid is really interesting, Jaise Kuriakose is the electrical engineer for the microgrid and has designed the system. I recommend having a read of the follwoing articles, blog posts and Jaise's presentation about the microgrid:

On the monitoring side there are pulse output kwh meters on all the renewable generators and non interruptible mains loads. As the microgrid is a recent addition, when I started these meters were not connected up to a data acquisition/logging system.

I spent the first couple of weeks connecting up these pulse output meters to the scada system that was in place for the previous monitoring setup and then configuring the scada system for the new metering setup.

The immediate aim of this was to get data to the microgrid public energy display, which I will write about next in part 2.....

Networked Arduino's and PV monitoring weekend

Last weekend a group of us gathered in the mountains of north wales (were I live) for a build session: Ken Boak and Suneil Tagore made the long trek from London and Cardiff and Glyn Hudson came from just down the road.

We spent the weekend developing a networking system for Arduino's applying it to monitoring a PV system. Ken Boak has written two good blog posts detailing our work on his blog, have a look:

Wired network for arduinos

The team from left to right: Suneil Tagore, Trystan Lea, Ken Boak and Glyn Hudson

Appliance Inference

A start on an investigation into the possibility of inferring what appliances are on and how much energy they use (especially their kwh per day usage) from one measurement point at the supply to the house/building. If this can be done effectively it would be a much cheaper and less intrusive way to find out such information than placing a separate meter on each appliance.

Alan Meany's Ambient Knowledge

Check out Alan Meany's Ambient Knowledge energy monitor project using the non-invasive Mains AC method, its a really nice idea, from Alan's website:
"Ambient Knowledge is a lamp that glows different colours to display the current consumption in your home. Ambient Knowledge is an Ambient Energy Information Display that provides you with energy information in a visually pleasing, easily accessible convenient, glancable manner. At a quick glance AmbientKnowledge will make you aware of how much energy your house is consuming in a subtle simple approach, with minimal effort needed."

Alan will be exhibiting Ambient Knowledge at Ars Electronica 2010 in Linz, Austria 2nd - 11th of September.

Project Update

This is a joint blog post from Suneil Tagore and Trystan Lea. Last week we met up in North Wales and spent a good part of the week looking at the next step for the openenergymonitor project. We thought about: How it could be organised and described better. How it could be made more useful for other participants/users/developers, and how it could better reflect our ideas for the project and also our activities using the technology.

One of the main aspects that we would like to expand on is the idea of modularity.

Lets say you build a solar hot water controller, the solar hot water controller has the Arduino microcontroller platform at its heart, 1 of the 6 analog inputs and 2 of the 14 digital channels is used for the 3 multiplexed RTD temperature sensors. 1 other digital channel is used for the pump control. That leaves 5 analog channels spare and 11 digital channels. The cost so far has been £20 for the Arduino and between £5-8 for the temperature sensor electronics and pump control. For another £12: the price of a couple of resistors, capacitors a CT sensor and AC-AC adapter: mains AC energy monitoring can be added using only 2 more analog inputs. The mains AC energy monitor and the solar hot water controller share the same arduino and can also share for example an LCD and ethernet connection. This ability to share resources enabled by such a modular system can ultimately yield significant overall benefits in terms of energy efficiency, material efficiency, cost reduction, convenience and usability compared with having a separate device for each energy monitoring and control application.

To make this possible one of the main tasks will be deciding on documentation standards so that each bit of documentation can fit together with the other bits, this will need a bit of thought and work.

Another important element of making modularisation easy to work with will be developing Arduino libraries for the modules so that the software side is straightforward to program and also possibly investigating standardized connections between modules.

To start with we thought it might be best to divide the modules into types:

Input modules

Modules for measuring things, for example: Electricity, Heat, light, wind, fluid flow, etc

Actuator modules

Modules for controlling things, for example electric pumps or dump loads.

Data Modules

Displays, Computer and Internet based graphing

Each module would have a description of what it is and how it works, a list of parts - including possible suppliers, circuit design (if applicable), and a section on how to connect it to an Arduino including details on software and calibration (if applicable).

The next part to the documentation is the builds section: how to bring more than one module together to do something more useful and interesting like a solar hot water controller or a solar hot water controller / energy monitor combo.

After that is case studies. Which brings us on to another important topic. As well as developing this technology we hope to use it in our own homes and also look into how we can use it as a part of a service that we could offer, at the moment one idea in its early stages is to explore offering an energy auditing ,renewable energy feasibility and renewable energy installation service in our local areas. Suneil is just in the middle of his first solar PV installation and is developing a solar monitoring unit for the installation. Both of us taught a wind turbine making course at Atlantic college in south wales this year, and as a part of that we will be installing wind turbine monitoring. The case studies section will document the use of the openenergymonitor project in projects like these. One of the aspects of this is that as we experiment with making a living we hope to help other do the same.

Last but very much not least: the updated website has a section on local manufacturing. One of the main things we would like to explore as a part of this project is the idea of local manufacturing: Being able to make the things we want and need either in our own homes or in labs/workshops and small businesses in our local communities. This is a really exciting idea and emerging possibility that was a large part of the inspiration to do this project.

To learn more about local manufacturing also often called decentralised manufacturing or desktop fabrication have a look at the following projects that are pionnering the idea: RepRap the project to build an open source 3D printer and MIT FabLab’s; 100kgarages; a book by Kevin Karson and more resources on p2pfoundation manufacturing page.

So over the next few weeks there shall be changes a foot on the website as we attempt to organise it along the lines of what we have described above and the project starts to move more along this direction.

We would like to thank Ken Boak who has helped us refine the ideas above, especially those on modularity. Ken Boak is very knowledgeable energy monitoring and sustainable technologies enthusiast, and documents many of his findings on his blog sustainable suburbia.

Please feel free to join in and share your thoughts and ideas on this project. The scope for developing new applications and real world case studies/installations is limitless; posting your findings here is most welcome in this collaborative project. Hope to hear from you soon!

Solar hot water controller

Well its been a while since I last updated, I managed to get some time over the last month to build a solar hot water controller for the navitron evacuated tube system we have installed here on our house, its been a project I wanted to do for a while. I've documented version 1.0 of the design here:

Apart from the usefulness of being able to log data from the solar hot water controller I'm interested in looking at combining data from the solar hot water controller with data from the energy monitor. It would be interesting to see if its possible to calculate accurately how much immersion heating is displaced by the solar hot water system as well as how well the system is working compared with its expected output.

Here is a graph of the different system temperatures plotted with flot

All Power Labs

A couple of weeks ago I visited All Power Labs over in Berkeley CA on the recommendation of Ken Boak who went over there for a workshop in March. All power labs are:

“ incubator for open source energy experiments and distributed manufacturing solutions. We work to generate physical tools and information resources for people exploring alterative energy through DIY innovation and online collaboration. We believe that a bottom up, participatory ecology in energy is just as possible as it has been in computing. And we expect the impact of such creative self-determination will be no less transforming than its been in digital realms.”

Their current main project is called the GEK gasifier, (Gasifiers Experimenters Kit). The GEK gasifier converts biomass (woodchip etc) into wood gas, this gas can then be run in a car or burned for heating or used to generate electricity by running a gas turbine (they have a gas turbine!)+ generator or internal combustion engine + generator. The gasifier+engine+generator combination is called the Power pallet and can produce 10kW.

Bear Kaufmann who is investigating the performance of the system was looking for energy monitoring equipment and so Mario and I went over to see the operation and work with Bear on getting some energy monitoring working.

The generator they are using is a single phase 3-wire generator that is effectively the same configuration as household electrical wiring in the states. The energy monitoring setup therefore consisted of 2 CT sensors for current measurement: one for each leg a step down transformer for voltage measurement.

The power pallet has a gasifier control unit (GCU) which is based on the Atmel ATmega 1280 which is used in the Arduino Mega and so the unit is compatible with and uses the Arduino IDE for programming. The GCU has a lot of things happening on it: it monitors temperatures and pressures and controls things like flow to keep the gasifier working efficiently, there are critical servo updates that happen about every 20ms and so the main challenge of the visit was to try to fit the energy monitoring on to the GCU, to fit the real power, apparent power, powerfactor, vrms, irms sampling and calculation into those 20ms time slots. Up until now I have usually had the arduino dedicate around a second to make these measurements and so the question was could we squash the energy monitoring down and still get accurate results. Luckily we found we could do this, by taking one wavelength long samples and then averaging around 10 of these one wavelength samples to get a more stable result and so now the power output and efficiency of the power pallet can be tested with out a lot of extra equipment just a couple of sensors, resistors and capacitors connected to the GCU.

Here's a test output with different loads:

For more information have a look at Bear's post and write up here:

I will also try to upload the code for single phase 3-wire and the one wavelength sampling soon as I get a chance.