Archive for August, 2009

The romance and reality of urban wind power

Thursday, August 13th, 2009

Its now possible to buy a 200 watt micro wind turbine for $449 from Jaycar electronics. A couple of years ago they were even including a four meter tower with the wind turbine. If you live in a windy flat spot with no trees or houses upstream of the prevailing wind it’s a bargain. But don’t waste your money buying one of these and putting it on top of your suburban house, in your backyard or on top of your office building.

Encraft in the UK have published the results of a trial on the operation of 26 building mounted wind turbines with a combined 168,950 hours of operation. The purpose of the trial was to see how grid connected small wind turbines performed on a range of building types and locations. It was undertaken in 2007 and 2008. A range of turbines from different manufacturers were tested, with capacities from 400 to 1,250 watts. The report includes photos of each installed turbine. Looking at the photos it becomes pretty obvious that the wind turbines that performed the best were mounted high, well above surrounding buildings.

The gist of the report comes in paragraph three “as anyone who knows anything about wind power will attest, urban environments and building mounting is probably the most challenging context in which to try to make wind power work.” The report then goes to show that the average availability factor of turbines in the trial was 0.85%, improving to 4.15% if turbines which were switched off or broken were taken into account.

At a 4% availability factor a 200 watt turbine would only produce 70kWh a year, about 20% of the energy used by a small energy efficient fridge. At a 1% availability factor that drops to under 20kWh. Take off the power that the generator might use and the effective power output could be zero.

The report notes that many of the turbines on the best sites (high rise) were turned off because of noise complaints.

Encraft say that the “technology is still at a development stage and is likely to make a tangible contribution to energy and carbon saving only on the most exposed site and tallest building.”

A couple of years ago I researched putting a small wind turbine on my surburban house. Someone from the wind industry advised that for the turbine to work it had to be twice as high as the nearest obstruction. Otherwise the air would be turbulent, reducing output and leading to early failure. I figured that building a 50 meter tower in my backyard and getting the necessary planning permit wasn’t worthwhile. And of course it also helps if you live in a windy location.

With this rule of thumb in mind it becomes obvious pretty quickly that urban or surburban wind generation in most cases just isn’t viable with current technology. And the UK study proves it. Maybe emerging technologies that may be able to operate better in turbulence may prove more useful in urban environments, such as the linear wind generator.

Linfox video on their carbon reduction program

Wednesday, August 12th, 2009

This 8 minute video shows how Linfox is going about reducing its carbon emissions. What stands out for me in this video is the broad commitment across the organisation to cutting greenhouse gas emissions. Use it to help inspire a similar commitment in your organisation.

Building Automation Systems don’t save energy

Tuesday, August 11th, 2009

Building Automation Systems (BAS), otherwise known as Building Management Systems (BMS) or Direct Digital Control (DDC) systems don’t save energy. But their operators can.

A BAS system will often cost the equivalent of around one year’s worth of energy bills. But unless its well operated it may never pay itself off.

BAS systems are complicated

BAS systems are complicated

BAS systems are complicated. In this respect they are similar to a jet airplane. But unlike airline pilots, in far too many cases the operators of the BAS systems have little or no experience, minimal training, and often very little time to operate it.

You wouldn’t buy a jet airplane without having appropriately trained and experienced pilots to fly it. But far too often organisations buy BAS systems without making the necessary investment in the people who operate it.

Unlike airplane pilots, where serious mistakes can be fatal, if the BAS operator makes a mistake the chances are very few people, if any, will know about it. Your building won’t crash and burn if the operator manually over-rides a time schedule and leaves a large fan running all the time. (I haven’t seen a BAS system yet where fans that should be on a time schedule have had their schedule bypassed.)

In many organisations, with energy costs 1% of less of total operational expenditure, the chances are that the accountant won’t be watching to ensure that any savings put forward in the business case for installing the BAS are actually achieved. Usually the only thing that everyone will know about, and have an opinion on, is the temperature inside the building. In response to this many BAS operators do everything possible to keep the building at a temperature that generates the least amount of complaints, no matter what. In some cases the energy implication of this are like a pilot flying from Melbourne to Brisbane via Alice Springs to avoid a bit of turbulence, rather than making intelligent small deviations to the direct Melbourne – Brisbane route to minimise discomfort to passengers.

And if you’ve outsourced the management of your BAS, are you auditing the performance of your contractor? How do you know your BAS contractor is operating your building for high energy efficiency? The contractor doesn’t pay your energy bills – and again may end up with the sole focus of keeping the building at a temperature that minimises complaints, without necessarily considering the increased energy consumption that this may cause. One of our customers has us auditing their controls on a regular basis, and we rarely fail to identify valuable energy savings because of wastage caused by shortcuts taken by their contractors.

Also unlike in an aircraft, when an alarm is raised by the system, the chances are that it will be ignored. Particularly if there are dozens or even hundreds of alarms going off every day, which is the norm rather than the exception in larger BAS systems.

And unlike a new jet, the chances are that your brand new BAS system may not have been correctly commissioned. For example one or more sensors could be in the wrong position and thus giving erroneous readings. An example is a recent customer’s building where the building manager couldn’t figure out why the system was running on 100% outside air most the time. After a great deal of investigation it turned out that the CO2 sensor (air quality sensor) was positioned in a copier room which had no mechanical ventilation (another mistake), and was thus reading too high, with the result that the system was running on 100% fresh air - at huge energy cost - to try and reduce CO2 levels.

To get the most from you BAS system invest in the person who runs it. Make sure they know the principles of energy efficient HVAC and building operation. Make sure they are well trained in operating your system. Set energy performance targets, and monitor them. Make sure they have enough time to actively operate the system, and aren’t just spending all their time dealing with alarms. Bring in experts to help configure the system and review it on a regular basis if necessary. Or else outsource management, but with clear performance targets and regular audits if necessary. And then the investment in your BAS will result in energy savings.

Clean coal air freshener video

Saturday, August 8th, 2009

Video by the Coen Brothers. See comments on this video on youtube.

Lifecycle efficiency of LEDS the same as compact fluorescent

Friday, August 7th, 2009

Research recently undertaken by Siemens says that the lifecycle efficiency of LED lights is equal to that of compact fluorescents.

Measuring the lifecycle efficiency involves looking at the energy to manufacture and dispose of the product, in addition to the energy it uses whilst in operation.

The report was released by Osram, which is owned by Siemans, with the testing taking place by the Siemens Corporate Technology Centre for Eco Innovation, and reported on in the New York Times.

There aren’t many details yet though as to how the research was undertaken or the numbers behind the claims. For example, was the LED light used in the comparison of equivalent brightness to the CFL. 

But it does show that LEDs are getting closer to being the light of the future.