Saturday, 26 May 2018

Why is Cambridge University dragging its feet on divestment?

How much time does it take to change investment policy at a university? Why do Cambridge university students need to go on hunger strike and occupy university office buildings to pressure the university to action? Back in January last year, after a vociferous campaign by students and academics the soverign body of the university ruled that ‘none of the University’s Endowment Funds should be invested directly or indirectly in companies whose business is wholly or substantially concerned with the extraction of fossil fuels.’ They also required the university council to publish a report within twelve months to set out how this should be done. It actually took a bit longer than that but earlier this month a report was produced (5 Mb pdf) and the recommendations in it, while not earth shattering, are a step in the right direction. However, even this is apparently a step too fast because the council are unable to agree to adopt even those recommendations. These include:

  1. No investment in tar sands or thermal coal (? What other kind of coal is there?)
  2. Commitment to the principles of the UNPRI (United Nations Principles of Responsible Investment)
  3. 10% of the fund to be invested in dedicated environmental, social and governance (ESG) funds

Saturday, 10 March 2018

How much energy can you get from rain?

Researchers in China have created a hybrid solar panel that can also make electricity from rain [1]. This has obvious advantages, especially for regions where you get more rainfall in winter than in summer because it will help to even out generation through the year. But how much energy can you actually get from rain? How does it compare with solar energy - and is it worthwhile? Here is a back of the envelope calculation.

Sunday, 11 February 2018

Uncertainty about pollution from wood stoves

In my previous post on air pollution, especially fine particulates (PM2.5), in Cambridge I concentrated on traffic, hardly mentioning wood stoves  as a possible source. However, wood burning is cited as an important source of pollution in parts of London [1] so why not Cambridge? To be honest I steered clear of the issue because there is such a huge amount of uncertainty I felt unable to present any facts with confidence. The National Atmospheric Emissions Inventory (NAEI) estimates that 35% of PM2.5 in the air is from domestic wood burning[2] - or it could be 10 times less [3].

The issue is so uncertain that the government is running a call for evidence on the issue. This runs until 27th Feb.  In their call for evidence they say [4]:
  • Burning wet wood (i.e. not properly seasoned wood) generates at least twice the emissions from dry wood.
  • Estimates for the proportion of wood that is burnt wet range from 80% (from the wood industry) to 20% (from a survey by BEIS).
  • Estimates of how much wood is burnt in total range for 3 to 6 million tonnes per year
  • Burning on an open fire generates up to 10 times the emissions from a modern wood stove.

Wednesday, 7 February 2018

Where does air pollution in Cambridge come from?

Air pollution is a big problem for our health, especially very small particles known as PM2.5 (less than 2.5 micrometres in size) that penetrate deep into our lungs. PM2.5 is more closely linked to death rates than the other pollutants [1]. Diesel cars are blamed for a large proportion of air pollution in our cities. But are they the only problem or even the main problem? Traffic is the main source of nitrogen oxides (NOx) in our cities but for particulates the story is more complicated.

  • Most NOx pollution in cities comes from traffic, mainly from burning petrol or diesel (especially diesel).
  • NOx dissipates fairly quickly.
  • Particulates (especially PM2.5) are partly related to traffic (including chemical reactions with NOx) but there are other sources.
  • Particulates can waft around and travel for long distances. Most of the particulates pollution in Cambridge comes from outside the city.

What this means is that while reducing traffic in the city, especially diesel cars, will reduce NOx levels, they will have less of an impact on particulates. Tackling that requires action across the region, not just the city.

Thursday, 25 January 2018

Is waste incineration sensible, a health disaster or a white elephant?

Amey have submitted a planning application for an Energy from Waste plant at their waste handling facility in Waterbeach [1]. Is this a good thing or a bad thing? There are potential concerns about air pollution, carbon emissions and disincentive to reycle. But it will divert stuff from landfill and probably reduce GHG emissions overall.

The facility will process residual waste – the stuff that has come through the Mechanical Biological Treatment and not been picked out as valuable, and the stuff that was rejected from the dry recycling plant, plus construction and demolition waste. This waste would normally go to landfill.

The waste will be burnt in a furnace at 850°C to produce electricity and also heat; they hope to supply district heating for new developments in the area.

Amey's main EfW inputs and outputs [1, section 4]

Friday, 12 January 2018

Would Green Mortgages make energy efficient homes more affordable?

Do you think lenders ought to take into account the energy efficiency of a house (and hence your energy bills) when deciding how much you can afford to borrow? In some parts of the country there appears to be a price premium for a good EPC rating - the overall average for England is an extra £16,000 for 2 levels of EPC grade (D to B or G to E) [1]. This is good news for owners and further encouragement to people thinking of upgrading their homes, but not necessarily good news for buyers. If lenders did take into account your energy bills, how much difference would that make?

Tuesday, 2 January 2018

A bottle deposit scheme is tinkering round the edges.

Much of the news reporting on the parliament report ‘Turning back the plastic tide’ has been about implementing a bottle deposit scheme for plastic bottles. However this is not the most important of the recommendations made.  The key ones, in my view, are those designed to build a market for recycled plastic and to shift the burden of handling packaging waste onto producers.

First a quick recap of the numbers. Annually in the UK
  • 13 billion plastic bottles used
  • 7.5 billion recycled
  • 3 billion incinerated
  • 2.5 billion go to landfill