Zero carbon, or not zero carbon? That is the question.

Posted on January 5, 2012 by jpreed

A student made me aware of an interesting recent  judgement by the Advertising Standards Agency (ASA). The complainant had challenged that “Solartwin.com zero carbon solar power & water heating” was misleading and could not be substantiated. The issue arose around the definition of “zero carbon” and whether  that description could be applied to the technology for sale.

The interesting part to me was that  the ASA upheld the complaint and I was keen to see their justification. This is where it gets “fun.” The assessment published on their website (linked above) does not actually seem to support their decision very well.

They state:

‘…we noted that within the Defra research paper, dated February 2011 and entitled “Consumer understanding of green terms”, only 46% of respondents stated they were very familiar or familiar with the term zero carbon. We noted that the report commented that “If unsure, participants often interpreted terms in their most literal sense (e.g. ‘zero carbon’ was often translated in the group discussions as ‘emits no carbon’).”‘

If unsure, “zero carbon” was taken to mean “emits no carbon.” This is actually how Solar Twin defined zero-carbon in their submitted material to the ASA, and the ASA noted this.

They continued:

‘We also noted the ad was for a solar panel supplier and considered that the availability of a product which produced zero carbon during its full life cycle was likely to be a factor that would effect a consumer’s transactional decision. Therefore in the context of the ad, we considered that consumers were likely to interpret the zero carbon claim to mean that no carbon was produced in the full life cycle of the advertised products.’

Here I think the key phrases  are “no carbon produced” and  “full life cycle.” Solar Twin provided evidence and the ASA noted it, that in fact although the products do contain embedded carbon from their manufacture, over a “full life cycle,” they effectively pay back the embedded carbon within their lifetime because they offset traditional fossil fuel derived energy (Actually, it could be argued that as they pay back the embedded carbon within their lifetime that the products are better than “zero carbon.”) One possible interpretation of this is that over the full life cycle of the products, no carbon is produced.

They conclude:

‘Since we understood that carbon was produced in the manufacturing process, we concluded that the zero carbon claim had not been substantiated and that the ad was likely to mislead consumers to their detriment.’

If I was marking this as a piece of students work I would have to say that their conclusion does not follow from their discussion! I can understand their concern, and it is important that consumers are not mislead about the possible benefits of domestic solar power, but I am not that impressed by the ASA grasp of the issues here.

Posted in ASA, Low Carbon, Solar Power, zero carbon | Leave a comment

Out of Time?

Posted on November 11, 2011 by jpreed

The International Energy Agency put out their World Energy Outlook (WEO) this week. I don’t seem to remember the WEO getting a huge amount of press usually, but this time it comes with a warning that guarantees headlines. “The world is locking itself into an unsustainable energy future which would have far-reaching consequences…” reads the tag line for the press release accompanying this years WEO.

The basis of the statement is that by commissioning new fossil fueled generation capacity and infrastructure now, we lock ourselves into using that technology for the foreseeable future and into emitting the associated greenhouse gases.

“The WEO presents a 450 Scenario, which traces an energy path consistent with meeting the globally agreed goal of limiting the temperature rise to 2°C. Four-fifths of the total energy-related CO2 emissions permitted to 2035 in the 450 Scenario are already locked-in by existing capital stock, including power stations, buildings and factories. Without further action by 2017, the energy-related infrastructure then in place would generate all the CO2 emissions allowed in the 450 Scenario up to 2035.”

The kicker is the IEA estimate that for every $1 not spent now on clean energy, it will take $4.30 in 2020 to have the same effect as that $1 spent today would.  The problem is that CO2 is a long lived gas in the atmosphere. About half of what we emit today hangs around in the atmosphere for centuries. Therefore delaying action to reduce CO2 emissions now places a heavy burden on our future.

This is basically the same message as a Real Climate post of last year. They show that it is not credible to delay action on reducing CO2 emissions in favour of easier short term fixes, because in the long run we will be worse off. At issue is that regardless of how many rounds of talks, how many CoPs or summits we go through, no one is able to agree on a course of action.

The perception seems to be that it is a problem we can address in the future, the reality seems to be that it is a problem we should have already addressed by now.

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Yet another round of cuts

Posted on May 18, 2011 by jpreed

The Government just can’t seem to stop announcing cuts! This week the Government has proposed a plan to cut GHG emissions by 50% from 1990 levels by 2025 en route to 80% cuts by 2050.

Under the Climate Change Act 2008 the government is committed to an 80% cut in GHG emissions by 2050. To realise these cuts the Government has to meet a series of interim targets. These targets cover 5 year periods and have to be set 3 periods ahead. We are reaching the end of the first period (2008-2012) and so they have now announced the proposed carbon budget for the 4th period (2023 – 2027).

The budgets for the 4 periods can be seen in Table 1. These budgets represent the sum of the amounts of GHG allowed to be emitted in each of the 5 years they span.

Table 1: UK interim carbon budgets.

Budget 1 

(2008 – 2012)

 Budget 2 

(2013 – 2017)

 Budget 3 

(2018 – 2022)

 Budget 4 

(2023 – 2027)
MtCO2eq 3018 2782 2544 1950
% reduction from 1990 22.8 28.8 34.9 50.1

This leads to the question: Are we actually going to meet any of these targets? It is all well and good proposing strict targets if we don’t actually meet any of them. In 1997 the Government pledged to reduce CO2 emissions by 20% from 1990 levels by 2010. This hasn’t come to pass. Preliminary figures from DECC show that only a reduction of 16.5% was achieved.

Cambridge Econometrics suggest that we are going to narrowly miss the first 3 carbon budgets based on their projections, whilst the Government projected last year that we would meet them.

To meet the first 3 budgets requires that GHG emissions drop about 1.2% of 1990 levels per year. This is not too far off the slope of UK GHG emissions from 1990 – 2007 as estimated by a linear fit, so on the face of things, it doesn’t look too far out of the realms of possibility that we might meet at least the first budget. Indeed Cambridge Econometrics think it will only be narrowly missed, but that for subsequent targets the gap between performance and target will widen. Currently, GHG emission reductions seem to be on target (Figure 1).

UK GHG Emissions

Figure 1: Annual UK GHG Emissions 1990 – 2010

One issue could be to what extent it is possible to decouple economic growth from energy use. From the preliminary figures for 2010 it doesn’t look as if we are there yet, emissions rose again as the economy started to recover. Although, not above the point they might have been at anyway. Another issue is the sustainability of the historic rate of decrease. Part of the existing decrease is due to the migration from coal fired power stations to combined cycle gas turbines. The relative costs of coal and gas are an issue here, as CO2 emissions in the UK currently broadly follow the amount of coal utilised for energy generation. This means that as the market fluctuates so too do emissions. Another part is likely due to the reduction in manufacturing capacity in the UK and our reliance on imports from overseas. In order to maintain and eventually increase the rate of decarbonisation (required to meet the 4th carbon budget) it will be necessary to invest in large scale development of renewable energy technology as well as energy efficiency measures. This would reduce the influence of coal prices on emissions by reducing the proportion of energy generated in that way. A knock on effect could be economic growth in the renewables sector and the UK as a whole as companies such as Vestas invest in the UK.

The policy designed to meet the 4th carbon budget will be announced in October.

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World Water Day

Posted on March 22, 2011 by jpreed

I have an article published today for World Water Day on the University Website that I thought I would leave a link to from here, it doesn’t go into too much detail about anything but has some links to places you can find out more. This one is probably a good place to start.

Posted in Climate Change, sustainability, Wastewater Treatment, Water Treatment | Leave a comment

What a difference a year makes.

Posted on February 1, 2011 by jpreed

This post is a belated update to the lies, damn lies, and statistics post from the end of last year. The below figure has been updated with the temperature anomaly for 2010, and we can see that it sits just where we expect it to be if global warming was continuing on as before. So, no surprise there then.

Global Yearly Temperature Anomolies 1975-2010 from HADCRUT3v

All of the commonly used data sets tell the same story. However, in order to clearly demonstrate that we need to use a “trick!” The three most commonly used surface temperature data sets are those developed by the Climatic Research Unit at UEA, GISS TEMP from NASA and the NCDC from the US Department of Commerce. In fact these are the data sets that the World Meteorological Organization uses to calculate the global average temperature (2010 is in a three way tie for the warmest year on record). As before I will plot annual means from 1975 to 2010, this time for each of the above data sets.

Global Annual Temperature Anomaly

We can see that the GISS and NCDC data sets agree pretty well with each other, but the HADCRUT data set is consistently lower than the others. This is due to the way the temperature anomalies are calculated for the different data sets. Each of the above groups calculates the temperature anomaly from a different base line. For HADCRUT the base line is from the average 1961-1990 values, for GISS 1951-1980 and for NCDC 1901 – 2000. These different baselines create the offsets seen in the above figure. Once we set all the baselines to the same value we can better compare the different data sets. (I have chosen to set all of the baselines to 1961-1990 as this is the baseline used in the previous post.)

Global Annual Temperature Anomaly same baseline

We can now see that the three different data sets agree much more readily with each other. We have to note that altering the baseline does not change the temperature trends. In fact anomalies are used precisely so that it is possible to easily look at trends in the data. This is because they represent changes in temperature and not absolute temperatures. We could imagine a scenario where we wanted to look at the temperature history of a couple of different sites, one with a higher average temperature than the other. In order to make meaningful statements about the relative temperature changes of each site in comparison to each other we would need to normalise the temperatures in some way. This is what baseline averaging to produce anomalies does and it enables us therefore to make comparisons between different locations and estimate trends accurately.

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All biofuels are equal, but some biofuels are more equal than others.

Posted on January 28, 2011 by jpreed

In the British Governments bonfire of the quangos last year the Renewable Fuels Agency (RFA) was abolished and had it’s functions transferred to the Secretary of State for Transport. The RFA was responsible for running the Renewable Transport Fuels Obligation (RTFO). The RTFO was set up to obligate fossil fuel suppliers to supply a specified percentage of road transport fuels as bio-fuel. The fuel suppliers are given certificates for bio-fuel they supply (or gain them through trading with other suppliers) and at the end of the year they use the certificates to show that they have complied with their obligations. In practice what this means is that the fuel that you buy at the forecourt will have a small percentage of bio-fuel blended with it. Currently the target is that approx 3.6% of road transport fuel by volume should be bio-fuel. This is all well and good, and modern vehicles can happily make use of 5% blends without modification. But the main driver for the use of bio-fuel is that of carbon abatement and sustainability. This is where the relevance of the title of the post should become clear.

The problem is that in order for the use of bio-fuels to make sense from a sustainability/environmental point of view, the bio-fuels need to be sourced sustainably. In order to make sure that this is the case,  obligated fuel suppliers  are meant to report on the “carbon and sustainability” of the fuel they supply.

The RFA has just published its Year 2 report on the RTFO and in this they detail the information supplied to them by the obligated fuel suppliers on carbon and sustainability. It turns out that only 31% of the bio-fuel supplied in the UK over 2008/2009 met the environmental qualifying standard. Now this is an improvement over the previous year (20%) but still some way below the government target of 50% for the year. Of the balance, the fuel suppliers either didn’t meet the standard or perhaps worse, failed to submit data regarding the sustainability of their bio-fuels.

BP, Chevron, INEOS, Morgan Stanley, Murco and Total failed to meet any of the Government targets set. These were meeting the environmental qualifying standard, greenhouse gas emission reduction targets, and data reporting of fuel characteristics.

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Lies, damn lies, and statistics.

Posted on December 16, 2010 by jpreed

In his 1954 book “How to lie with statistics,” Darrell Huff devotes a chapter to the “Gee-Whiz” graph. He shows that by truncating figures and altering the proportions between axis that it is possible to create a misleading impression without falsifying any data.

For people who would like you to belive that climate change isn’t a big problem this approach can sometimes be too tempting to avoid. A prominent think tank has a figure similar to the following on their homepage.

I have used data from the UEA Climatic Research Unit to reproduce the figure. There doesn’t seem to have been much in the way of global warming over the last decade, right? But if we want to see if “Global Warming has Halted,” we can use the same data source to take a look.

Borrowing an idea from Tamino, in the below figure I have plotted global mean yearly temperatures from 1975 up to 2000, using the same data source as for the figure above. I have also plotted a trend line (0.0174 °C∙yr-1) estimated by linear regression and dashed lines representing ± twice the standard deviation of the residuals. The idea is that aproximately 95% of the yearly values should fall between the two dashed lines. (Actually, to get things completely right, I need to account for autocorrelation of the residuals, but it shouldn’t make too much difference for our purposes.) By extending the dashed lines forward in time to the present we should be able to see if warming has halted or not.

If when the data points for 2001 – 2009 are included they sit within the two dashed lines, then claims that global warming has halted would seem to be premature. In fact as the below figure shows, the global mean  yearly temperatures for 2001 – 2009 are right where we would expect them to be if global warming were continuing without pause.

 

Posted in Climate Change, Statistics | 4 Comments

Yes, but how many Jumbo Jets is that?

Posted on November 25, 2010 by jpreed

In the Guardian yesterday they announced a Gamesa led project to develop the “worlds largest offshore wind turbine.” It will be a 15 MW machine that would be “even bigger” than the 10 MW Britannia turbine also under development by Clipper Windpower. Unfortunately they neglect to tell us how much bigger it would be. Even more importantly they neglected to tell us how many Jumbo Jets that is. Fortunately, they provide an estimate of the size of the Britannia turbine that we can use to make a guess at the size of the Gamesa led turbine as long as we make some reasonable(?) assumptions.

1: Both turbines are horizontal axis types.

2: Both turbines have the same rated windspeed.

3: Both turbines have the same power coefficient.

4: Air density is a constant.

This means we can use the ratio of the rated powers of the two turbines to find the ratio of their swept areas and from there the diameter of the Gamesa turbine.

So: 15/10 = 1.5

From the link the Britannia would have a rotor diameter of 150 m. This gives a swept area of about 17672 m2. Therefore the swept area of the Gamesa turbine would be 26508 m2, it’s rotor diameter would be about 185 m and the turbine would be about 220 m high.

A Jumbo Jet (747-8) has a wingspan of 68.5 m so this means the Gamesa turbine would have a diameter equivalent to 2.7 Jumbo Jets. Thats half a Jumbo Jet larger than the Clipper.

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