You may have come across this news item a couple of months ago but it is worth taking another look. Although, the study was conducted by a major spam-ware corporation, it is clear that junk e-mails have a huge carbon footprint.

(image: www.fotolia.com)

Anything powered by electricity emits greenhouse gases. Recently research was conducted in the US to find out the amount of energy needed to transmit, process and filter spam globally. The results were startling. According to the ‘Carbon Footprint of Spam’ report the average greenhouse gas emission of a single spam message is 0.3 grams of CO2. Is this a lot? Well, if you multiply this by the number of spam sent annually it translates into a huge figure.

It is estimated that there are 62 trillion junk e-mails sent each year. In terms of energy this equals to the energy needed to drive a car around the planet 1.6 million times. If looking at the electricity needed to power these spam it equals to 33 billion kWh. This amount of electricity could power 2.4 million homes for a year! Spam-related emissions for all e-mail users around the world in 2008 totalled 17 million tons of CO2 or about the same as the emissions produced by 3.1 million passenger cars. That’s 0.2% of the total global emissions.

The report found that about 85 to 91% of all e-mails globally is spam. Nearly 80% of the spam-related GHG emissions came from the energy used by the PC users viewing, deleting and searching for legitimate e-mails amongst the junk e-mails. But spam filtering itself accounts for about 16% of spam-related energy use. To view and trash a piece of spam takes about 3 seconds.

If every inbox were protected by spam filters, organisations and individuals could reduce today’s spam energy by 75% or by 25 billion kWh per year. This would save the same amount of greenhouse emissions as produced by 2.3 million cars. In late 2008 a major source of online spam was taken off line and global spam volumes dropped by 70%. However, there are always new ones to take its place.

David Jones, the bureau of meteorology’s head of climate analysis, as reported in the the Age, said earlier this week that temperature benchmarks for August had been broken in every state and territory. ”In duration, extent and the magnitude of anomalies it is beyond historical experience and it hasn’t finished,” he said.

See full article at the Age newspaper.

I find this very disturbing. It appears that climate change is happening very quickly, reinforcing again the need for urgent action to cut emissions.

This week the weather is not what we expect for winter. Melbourne is known as a place of changeable weather, so I can’t recall a winter where we have had 5 or 6 nights in a row of strong winds. In Brisbane the temperature was 32 degrees Celsius yesterday. Its winter for goodness sake!

So are we going to look back at this time as a period of climate change or the start of climate change? The science seems quite clear. Unless we can quickly slash the amount of greenhouse gas being generated by human activity, the climate will continue to change. My young children may never in their lifetimes know what it is like to live in a stable climate.

The famous Dr Seus children’s book The Tale of the Lifted Lorax finishes by saying “unless someone like you cares an awful lot…”

Unless we get global emissions reduction quickly, 2009 will be viewed historically as a year back in time where people started to notice that the weather was changing. Unless we quickly stop putting great amounts of carbon dioxide into the air, stabilise, then reduce atmospheric levels of greenhouse gases people won’t be looking back and saying “2000 to 2030 was the time where the climate changed quickly.”

Think about this next time you make or support a decision that results in greenhouse gas being generated somewhere.

A new report has identified that the USA could reduce its energy consumption by 23% by 2020 through energy efficiency.

The report has been prepared by McKinsey and Company, who are well known for their studies on the economics of cutting greenhouse gas emissions.

McKinsey however says that this sort of saving is not easily achieved. Three types of barriers to the uptake of energy efficiency are identified in their report – structural, behavioural and availability. They say that these barriers need to be overcome to realise the full potential of energy efficiency across the economy.

Structural barriers are those that prevent an end user of energy from saving energy. For example a tenant typically has no control over the type of heating and cooling system in the building.

Behavioural barriers are those where ignorance or unwillingness to act mean energy efficient solutions aren’t implemented. An example that we see quite often in commercial buildings is ignorance about the time the air conditioning starts in the morning. Often it will be starting two hours or more before the building is occupied in the morning – which is wasteful if it only takes half an hour to get the building to a comfortable temperature.

Availability barriers are those where the user wants to reduce energy, but can’t access the solution or technology, often for cash-flow or cost reasons. For example, a business with tight cash flow that knows its HVAC system is a clunker, but doesn’t have the cash for an upgrade.

The report proposes various solutions to these barriers, mostly showing what government could do. The prescriptions appear valid for any government, not just the US. If you are in government, or have some influence in government circles, this report is worthwhile looking at.

Click here for the report.

Whilst these sorts of reports can be useful, they come with the implicit message “Think climate change – think government.” Don’t fall into the trap of thinking that just because another report is recommending the government do more, that it’s the sole responsibility of government to cut greenhouse gas emissions. There is a lot you can do yourself, and with focus and creativity these barriers can be overcome. Your organisation could probably cost effectively achieve a 23% saving from energy efficiency within a couple of years if you make this a priority. And the greater the number of individuals and organisations who make this a priority, the greater the impact.

Go to the department of climate change’s website and you’ll see the slogan “think climate, think change”.

Here in Melbourne the department of climate change’s slogan could be rephrased as “Think climate - watch change”.

In the 1980s vehicle number plates here in Melbourne proudly bore the slogan “Victoria – the garden state”. Fast forward twenty years to 2009 and Melbourne is now the driest capital city in Australia. Six months ago we had our worst ever bush fires. The newspapers this week have been saying that fire danger is going to be even worse next summer. 

This is precisely what most governments have been doing for a long time now – thinking climate – watching change - and not doing enough. The Australian Government ratified the United Nations Framework Convention on Climate Change, along with most of the rest of the world, back in 1992 (yes, SEVENTEEN years ago!).  Back in 1992 this is what Australia and many other countries agreed to:

“Where there are threats of serious or irreversible damage,lack of full scientific certainty should not be used as a reason for postponing such measures [to anticipate, prevent or minimise the causes of climate change]”, UNFCCC, 1992

“Think climate, think change” is a start – yes we need to think about this issue – but we need to go beyond thinking to action – all of us, not just the government. I much prefer the message developed by Darebin City Council – “think climate, make change”. Now.

You can reduce your own carbon footprint significantly if you want to. You can encourage those you know to do the same. And if you are an entrepreneur – think up solutions that cut carbon emissions then make them a reality, like Shai Agassi at Better Place. “I’m an imagineer. I imagine the future and engineer towards it.”

(Part Two) The first part of this topic was published on the 8th of May.

Flat Plate Solar Collectors

Flat panel (aka flat plate) collectors work on the principle of copper pipes running through a glass covered collector, often connected to a water storage tank on the roof. The hot water can then thermosiphon itself in and out of the tank, thus heating the water. Finally the hot water is gravity fed into the house from the roof. This is an extremely efficient way of gaining and storing hot water and can be over 90% efficient in the right climate. The simplest combination is the close-coupled system (see photo below).

However, the water tank may be located in the roof space or on the ground as a separate unit in which case a pump is necessary to circulate the water. This is known as a split system. Flat panel collectors are still the most commonly used collectors in domestic hot water applications in warmer climates due to their affordability and reasonably easy installation. The collectors should last well over 20 years and can handle an operating temperature up to 80 degrees.

Evacuated Tube Solar Collectors

Evacuated tube collectors consist of glass tubes with a layer of heat absorbent coating inside them. As the tubes encasing the water pipes are a vacuum it greatly reduces heat loss. The thermal energy retention can be up to 97%. Copper pipes run through the centre of these evacuated glass tubes in a U-shape. These are all connected to a common manifold which is then connected to a slow flow circulation pump which pumps water to a storage tank below. The hot water can be used at night or the next day due to the insulation of the tank. Evacuated tubes are often used in commercial applications or in applications where hotter water is needed, since they are capable of generating temperatures above the boiling point of water (for example on dairy farms). While evacuated tubes have a long life similar to flat plate collectors, they are composed of fragile glass tubes which may occasionally need replacement.

Comparisons

As pointed out in Part One of this blog it is not a simple matter of using evacuated tubes or flat panels as each circumstance is different. Each collector design has its own merits. Both systems can save over 3 tonnes of GHG emissions per year and can reduce heating energy consumption in a home between 50%  to 80% especially when electric hot water storage systems are being replaced. In addition both systems can be up to 70% efficient when heating water and heat losses in the system are taken into account. So instead we should look at the benefits and the short comings of each system.

Evacuated Tubes

Advantages

• No heat losses due to convection and conduction because glass collectors are hermetically sealed.
• No change of performance during the service life of the collectors as there is no corrosion.
• Thermal diode operation principle, the hot water flows one way only from the collector to the tank and never the other way around.
• It is able to harness sunshine from all directions due to its cylinder-shaped glass tubes.
• Well-suited for colder climates with reduced hours of sunshine, where frost may be a problem or where the roof is prone to overcast from clouds.
• Freeze free so can be used in sub-zero temperatures and in the presence of snow.
• Easy installation due to light weight and no maintenance needed afterwards.
• Requires smaller roof area for installation.
• It is less apparent on roof because of the absence of a water tank coupled to it.
• Each glass tube is independent from each other so in case of breakage it can be replaced.
• Minimum greenhouse emissions when combined with gas boosting.
• Saves about 3 tonnes of CO2 annually when compared to electric storage.
• Very low running cost when used with gas or off peak electricity.
• On average it is about 5 years payback on investment.
• Suited for commercial and industrial applications.

Disadvantages

• Expensive to purchase due to more components, such as pump, separate water tank and associated plumbing and electrical work.
• Less cost effective than flat panels based on initial investment.
• Glass tubes could break easily in a hail storm or from falling branches.
• In higher ambient temperatures it is less efficient than flat panels.
• In direct summer sun it could be too efficient making the water too hot which results in wastage.
• Evacuated tube collector’s aperture area is typically between 60 and 70% of the gross collector area (meaning that’s how much of the total area exposed to sun is doing useful work).
• Some heat pipes are prone to cracking rendering the system useless especially at the braising points. These don’t like repeated heating and cooling down especially if it is very sudden.
• The welding should be done with silver alloys to prevent this from happening.
• Mainly made in China, thus not supporting Australia.

Flat Panels

Advantages

• Operates extremely efficiently in warmer climates and in higher ambient temperatures especially when water tank is horizontal and adjacent to the collectors.
• It can be between 44% to 76% more cost effective in warm climates than evacuated tubes.
• Losses are minimised because of water tank being located next to collectors.
• Thermosiphon operation minimises maintenance – no moving parts or distant pipes.
• Simple to install as system can be purchased as one unit with collectors and tank together.
• Affordable to purchase for the above reasons and because of less plumbing involved.
• No electrical installation required in most cases where stand alone system is used (ie the tank is not separate from the collectors).
• Space saving as water tank is located on roof and not in or around the house.
• Robust construction.
• Large collector area.
• Flat plate collector’s aperture area is typically between 90 and 95% of the gross collector area.
• Mostly made in Australia for Australian conditions, which supports the local industry and economy.

Disadvantages

• Can corrode.
• The air gap between the absorber and cover pane could result in heat losses during cold and windy days.
• It can rob the water of built up heat if the collector becomes colder than the water temperature.
• No internal method of limiting heat build up and have to use outside tempering devices.
• In colder climates it may need extra protecting devices from frost or freezing.
• It is more reliant on accurate northern exposure in order to operate efficiently.
• Installation could be difficult due to weight and size.
• Circulates water inside insulated areas. Prone to leakage, corrosion and restriction of flow due to possible airlock.

The graph below compares the three main types of solar hot water systems and their efficiency.

Explanation: Solar collector efficiency is plotted as a straight line against the parameter (Tc-Ta)/I, where Tc is the collector inlet temperature (in °C), Ta is the ambient air temperature (in °C), and I is the intensity of the solar radiation (W/sq. m.). Notice that inexpensive, unglazed collectors are very efficient at low ambient temperatures, but efficiency drops off very quickly as temperature increases. They offer the best performance for low temperature applications, but glazed collectors are required to efficiently achieve higher temperatures.

Summary

From the above descriptions and considering the merits and drawbacks of each system the following conclusion can be drawn. In warmer climates and most temperate zones, where there is good exposure to sunshine throughout the year, and the ambient temperature is fairly stable the flat panel collectors are recommended to be used. Also, if there is good uninterrupted northern exposure available the flat panel is more economic. The flat panel is extremely efficient and the systems can produce sufficient hot water for most households. The use of a flat panel system will result in up to 80% reduction of hot water cost when compared to electric storage units. These are also more affordable with a faster payback period on investment. They are designed and made in Australia for Australian conditions.

On the other hand the evacuated tube systems have an advantage of being able to operate in colder climates or where there isn’t enough sun light (ie. some alpine or mountain areas, prone to overcast or where there are more trees). These systems also work well in the presence of snow or sub-zero temperatures. The unique design of the glass tubes allows it to capture sunlight from various angles thus heating the water for longer periods. In some cases where very high water temperatures are required – even in warmer climates- the evacuated tubes have the ability to produce water at higher temperatures than flat panels. Being smaller in surface area these units could be more suitable where there is a lack of space. Again 80% reduction in hot water cost and GHG emissions are quite achievable from such a system.

Please take note of the references for the graphs and information in this article. Where possible we have used information stemming from government websites, academic resources, and manufacturers data. If you need more information or actual references please contact us.