LED Lighting

My first experience of LED lighting was in 2009 when I used a 12 volt 1.5 watt lamp as part of a very small solar powered system.  This device consisted of a cluster of conventional white LEDs, whilst it was not a solution to lighting the home, it was used in the garden where it was suspended over a table so we could see what we were eating (and drinking).  For a very small input of energy, we were saved from our son's early attempts at barbecuing and filled in the time by reading a newspaper.

I've been aware of LED lighting as an emerging technology, so in 2012 a purchased a 7 watt unit which whilst being similar in appearance to an incandescent lamp, consisted of a light emitting surface and a not very effective diffuser.  Sadly this did not win the hearts and minds of my family, however, it is now mounted in a standard lamp and directed upwards at a white ceiling, provides a pleasant ambient lighting effect with limited impact on the electricity bill.

At this point, it seemed that LED lighting would work well where only direct lighting was required, for example in a desk lamp.  So early in 2013 I invested £5 in a 3 watt "spot" lamp which works very well.  My working area is now lit with 10 watts of LED lighting.

Over a seven year period, the energy used to light my work space has dropped from the 200 watts used by incandescent lamps in 2005 to around 10 watts with LED devices in 2013.

Ever since the days of gas mantles and oil lamps, most homes have been illuminated with a combination of direct and diffuse lighting.  With the advent of electric incandescent lamps, the most common lighting scheme was a single 60 or 100 watt lamp hanging from the ceiling, if you were posh there might be a couple of wall lights with candle shaped bulbs and readers of "Homes and Gardens" had standard lamps with lace shades, known to some as "tart's knickers".

Until recently, there has not been readily available LED lamp with the geometry to provide a point source of light with enough output to bounce off walls and ceilings.  However, I have just purchased a 3.5 watt LED which has an output of 230 lumens which is capable of replacing some 10 - 18 watt CFLs.  More importantly, my wife thinks this is a good idea.

Over the next few months we will experiment with LEDs around the house.  I guess we may have to add some more fittings and make some adjustments to completely replace CFLs.  This will allow the steady reduction in our electricity consumption to continue.  Whilst I'm interested in energy conservation, I won't/can't make massive capital outlays, however LED lighting does not require this and equally important pays back in between three months and three years.  This makes economic sense.

Over the past few years our electricity consumption has steadily fallen from more than 20 kwh/day to maybe less than 5 kwh/day.  This has been achieved by doing little more than taking account of energy consumption as household items have had to be replaced and a general awareness resulting from reading the meters occasionally so that we are aware of what we are consuming.  I hope that I appear normal and not obsessive.

This has lead me to the opinion that much energy policy is based on supporting high priced capital items such as roof-top PV (feed-in tariffs) and ground source heat pumps (renewable heat incentive).  Whilst I accept that there might be some merit in these schemes, they only appeal to people with surplus cash resources who are not a large part of the population.  They also act to create a perception that energy sustainability is expensive, whilst if done properly can reduce energy costs.  My current view is that low cost technologies which can be adopted by a large proportion of the population should have a higher priority.  I suggest that LED lighting, energy meters placed in the kitchen which display the current energy bill as well as the amount of energy being consumed and zoned heating would significantly lower domestic energy consumption.

The business model used by energy companies is also part of the problem, at 25 kwh/day I am a good customer, at 3 kwh/day I'm less attractive and possibly a nuisance, yet the economy as a whole needs viable energy suppliers, that problem requires a better mind than mine.

Blogger's Note

It's sometimes fun to take an argument to its illogical conclusion.  I sometimes read small chunks of The Guardian on my phone around 05:00 in the morning when it is still dark, to avoid waking my wife I don't turn on the bedside light.  Whilst a liberal press can guide my mind, I do have to turn on a light to find my way to the lavatory safely, thus it is unlikely that smartphones will replace domestic lighting.

Buckets are not only for beer

At university during one of the oil price shocks we were sent off to investigate the potential of chicken poo as an energy source, with hindsight, I now realise that this was just a subtle marking scheme.  In the first years of the 21st century we were going to save the planet by strapping wind turbines to our chimney pots.  Despite the general tone of this blog I support the concept of a sustainable energy economy, but building one is a big, big challenge.  As I stare out of the window, I can neither smell chickens or see a wind turbine, but there may be some rooftop PV lurking in the shadows.

Wind and solar installations are energy conversion systems, for example wind turbines take something that blows your hat down the street and turns it into electricity which you can use to light your home.  Baz Luhrmann has remarked on sunscreen.  Whilst you can learn much about wind and solar energy by staring at maps and graphs, messing with models and prototypes is also instructive and much more fun and this was where the Solar Bucket started around 2007.

The Solar Bucket, so called, because for a short time some of the bits were located in a bucket before being moved to a large sandwich box.  The concept was simple, a 4.7 watt solar panel charged a 3.2 AH lead acid battery during the day, overnight the energy stored in the battery was used to power something.  Initially, the something was a couple of 10 watt resistors, whilst these provided a steady load, they were a bit boring, so after a few months an old computer case fan was installed.  This was a bit more entertaining, but failed to grab the interest of either my family or neighbours, the breakthrough came with a 12 volt LED light which was bright enough to read a newspaper and more appropriate to my family, light the outdoor dinner table so that we could see what we were eating.  The energy yield was determined by giving the battery an hour to stabilize at dawn and dusk and then measuring the voltage, the battery having been previously calibrated.

A more detailed description can be found here:

The Solar Bucket

This page also contains links to results and discussion.

Compared with virtually anything found in a school lab, this was a crude bit of equipment, but over the period 2008/2009 generated enough data to produce this.

Underlying this graph is a learning curve and in particular how to manage the battery.  The battery was much too small and probably suffered damage from overcharging during the summer months, only later did I learn enough about power electronics to give the battery some protection and also a bigger battery would have helped.

Whilst undeniably crude, this experiment taught me some useful lessons.  Close to the top of the list is the challenge of seasonality.  We're 50 degrees north of the equator, so the sun is low in the sky in winter and often hiding behind cloud, so unless a solar energy system is going to be stupidly large you are not going to get through winter without either a backup or a complementary technology, such as a wind turbine.  Next, was the importance of energy management, the LED light worked because it was efficient and was able to use the energy in the form which it was available , i.e. 12 volts DC.  Whilst its possible to provide a range of low DC voltages with reasonable efficiency, there are higher losses associated with moving to 240 volts AC which is what many domestic devices expect.  Most important is the opinion that storage is the missing link in the sustainable energy economy, this is especially true for solar energy systems because the Sun does not shine at night and some summer days can be a bit dreary also the demand for power rarely matches the supply.

A couple of pictures show the reality:

This is my favourite picture of the Solar Bucket.  The panel was easily restored to functionality with a yard broom but without this simple maintenance the energy yield would be zero on a snowy day.  Bird poo also made a return visit to renewable energy.

This is the computer case fan, the blue LED's gave a frisson of excitement to task which often involved standing in the rain.

I recommend this experiment to politicians and policy makers.