Tuesday, 22 November 2016

Heating our homes with bio-gas - how much can we grow?

Ecotricity have released a report claiming that their green gas mills (making bio-gas from grass) could generate enough gas to heat 97% of our homes by 2035 [1]. Is bio-gas a practical solution for low carbon heating? It would certainly be less hassle than converting the grid to hydrogen (see Converting the gas grid to hydrogen, starting with Leeds) or installing expensive insulation. Let's look at some numbers.

According to Ecotricity:

  • One gas mill supplies 3500 homes (now) or 5000 homes in the long term, because gas use is falling - a reduction of 30% per home.
  • 5000 gas mills could supply 97% of households (maximum scenario).

Thursday, 17 November 2016

Converting the gas grid to hydrogen, starting with Leeds.

Low carbon electricity is within our sights but low carbon heating is more difficult. Most UK homes use natural gas (methane) and switching to renewables (electricity or biomass) is expensive, even when it is practical. Northern Grid Networks (NGN) have another suggestion - converting the gas grid to supply hydrogen.  This is carbon free at the point of use but not usually where it is made - the NGN proposal is to convert from methane and sequester the carbon stripped off. This will give, at their estimate, 59% reduction in emissions. However once have we have a hydrogen distribution network other options, including carbon negative ones are possible. The big questions is, is it practical to convert the grid to hydrogen? NGN propose that we use Leeds as a pilot city and they have produced a detailed plan: H21 Leeds City Gate. They have convinced me that it is technically possible, and the biggest barrier is cost, but even this is not ridiculous compared to other means for carbon savings. The diagram below shows the concept.

Overall concept for H21 - including gas supply to the steam reformers, salt caverns for storage and hydrogen pipelines. In the city hydrogen would flow through the existing gas distribution network. Image 1.6 from [1].

Monday, 14 November 2016

Cost of carbon savings

I have been criticised in the past for describing energy saving measures in terms of payback time so in this post I present costs of a range of different measures in terms of £/carbon saved. The measures include: a community wind turbine, PV on your roof (with or without battery), cavity wall insulation, solid wall insulation, new condensing boiler, more efficient freezer. Also I have included a one-off saving: travel to Berlin by train instead of plane.

Wednesday, 9 November 2016

From despair to determination - Trump will be president of the USA, not the world.

My first reaction to Trump becoming president of the USA was utter despair. But then I remembered - the USA is only accountable for 15% of global climate emissions. So even though they will doubtless wobble for a few years that need not be the end of the world, provided the rest of us act responsibly.

Emissions by country 1959 to 2014 according to the UNFCCC. Data from
UNFCCC (May 2015) and Boden, TA, Marland, G and Andres, RJ 2015. Global, Regional, and National Fossil-Fuel CO2 Emissions, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., USA doi 10.3334/CDIAC/00001_V2015, via http://www.globalcarbonproject.org

Tuesday, 1 November 2016

Energy saving week tips

It is energy saving week. If there is one time of year when you think about saving energy, this is a good time to do it because there is lots of advice out there. (If you live in or near Cambridge, you could go to the central library and get Tania to show you tools to help you. Also she can show you the pilot version of DAREED, a city-scale smart energy management tool - the current version is underwhelming but I can see the potential.)

Tuesday, 25 October 2016

How can we ramp up conversion to heat pumps?

The CCC recommends we need 2.3 million domestic heat pump
installations by 2030. At the current rate of 450/month by 2030
we will have 108,600 - just 5% of that target.
The Committee on Climate Change (CCC) recommends that to achieve our 2050 carbon targets we need the vast majority of homes to use heat pumps fuelled by low carbon electricity - and to get there in time we need to start ramping up the supply chain now. CCC says we need at least 2.3 million heat pump installations by 2030 [1]. Based on RHI statistics we currently have about 33,000, and there are 450 new installations a month [2]. At this rate, by 2030 we will have 110,000 - only a small fraction of the number we need. Of course heat pumps are only one technology that we need to ramp up - there are lots of others and they all need some kind of price support. The Renewable Heat Incentive was supposed to provide this for heat pumps but it isn't working. It seems to me that we need a carbon tax.

Monday, 17 October 2016

If we had infrastructure like the Dutch, how many of us would be cycling?

I have been having fun with the PCT (Propensity to Cycle Tool) which estimates how many commuters would cycle, based on a different scenarios. Cambridge has a high proportion of cyclists already but there is still scope for improvement.

Looking at Cambridgeshire as a whole, as of the 2011 census 9.7% of commuters cycle but if we behaved more like the Dutch it would be 23.7%. You can use the map view to drill down into specific routes. In the snapshot below I have activated the popup on a section of the Madingley Road. In the Go Dutch scenario we could have 80% more cyclists.
Screenshot of the PCT showing potential for increased cycling on the Madingley Road in the Go Dutch scenario