Friday, 4 August 2017

Drawdown - review

My beloved has given me a copy of 'Drawdown - the most comprehensive plan ever proposed to reverse global warming, edited by Paul Hawken'. It is a superb book in many ways - incredibly ambitious and a real eye opener.

The book ranks 80 wide ranging strategies in terms of potential carbon savings, with estimates for up front costs and overall financial savings to 2050. Strategies range from wind power to vegetarian diets, from district heating to educating girls. There were some in the agriculture section I had never heard of such as silvipasture (growing trees and grass together for animals and tree products) and improved rice cultivation (a combination of improved planting schemes and intermittent drainage).

Some of the rankings are surprising - but on a closer inspection this is often due to their method of accounting, whereby only carbon savings over the business as usual scenario are included. This increases ranking for strategies that are not currently widespread, which is a good way to bring them to our attention.

Friday, 28 July 2017

What does a sustainable energy system for 2050 look like?

The National Grid recently published their annual 'Future Energy Scenarios' report which describes alternative futures for electricity and gas supply and demand to 2050. There are four scenarios of which only one satisfies our carbon commitments but I am struck by how similar they are in terms of electricity generation - where they differ greatly is in gas demand and use of smart technologies to manage infrastructure - including smart meters and time of use pricing.

Friday, 14 July 2017

One year on from the inverter upgrade

We installed our PV panels in 2011 and last year we upgraded the inverter system, installing SolarEdge equipment. We were promised better yields, but are we getting them? After one full year with the new inverter I have a reasonable answer. In this post I show how I have estimated the improvement, correlating yield with the old system with weather data from the MET office and using this to predict what we would have got recently if we had not upgraded. The prediction function I derived was 98% accurate, which I was very pleased with. Using this I have estimated the improvement to be 5.9%.

Tuesday, 11 July 2017

How much water is it OK to waste?

All water companies waste water through not fixing leaking pipes. This is OK up to a point. There is something called a 'sustainable economic level of leakage' which is the level where the cost of fixing leaks and the cost of not fixing them balances out, taking into account environmental costs. Obviously environmental costs are hard to put a finger on. So what is acceptable?

Monday, 26 June 2017

Climate change in Cambridge

We know global temperatures have been increasing - it is happening here in England too. Here are some charts based on MET office monthly average data since 1910 [1]. The clearest changes are in minimum temperature. I see no trends in rainfall, which surprised me.

These are for East Anglia (which includes Cambridge where I live). The blue lines are the 10 year running average. The first chart is for August. There is considerable variation even in the running average and the increase is not linear but is more marked since about 1995.
(max - min) for the running 10 year mean is 2.1C. In my lifetime the change is 1.3C.

Friday, 23 June 2017

More energy label confusion coming

Under the EU energy label scheme appliances were originally labelled A-G with A as the best. Then as standards improved new grades were introduced: A+, A++ and for some products we now have A+++; apparently this is confusing. So the EU is updating the scheme with a rescaling so everything goes back to A-G: they say this is simpler. However, during the changeover period we will see two kinds of labels which is going to be even more confusing. Fortunately for most products there is other information on the label that you can use to compare products by actual energy consumption. Unfortunately this is not so for heaters, which only show the energy class and even this means different things for different types of heater.

Tuesday, 13 June 2017

Reasons why your freezer may be using too much electricity

Back in 2014 I reported some shockingly high energy use in a minority of freezers and fridges [1]. This was from a study of electrical appliances in general and there were only about 130 cold appliances in the sample. Now there has been a much bigger study with 998 fridges and freezers, conducted by BRE [2]. It has confirmed the earlier findings and provided more information as to the causes of the problem. In some cases the appliance was faulty but half the time the main cause was simply running on fast freeze or maximum setting all the time.

This problem mainly affects freezers. 25% of chest freezers were over-consuming and 12% of upright freezers.