Zero carbon Britain 2013

The centre for alternative technology have brought out another Zero carbon Britain report.   There is not the space to blog on the full report, but here some of the main points of interest as far as we are concerned.

Energy conservation

Zero carbon Britain envisages a reduction in energy use from the current 1,750 TWh to around 665 TWh per year (60%).  This is largely to be brought about by insulation and much more efficient use of energy (smart meters and smart demand as we cover in our book).  Industry and domestic users switch to electricity and synthetic methane.  Zero carbon Britain does not advocate a way of getting there but describes a number of approaches (such as TEQ’s or carbon taxes) with their pros and cons.

In my view. Gone is the previous Zero carbon Britain reports reliance on implausible numbers of house demolitions.  However the report is too vague on how we really get such a huge reduction in energy use.  The drivers for this will have to be very strong.  Other than TEQ’s which is my preferred option (see our book for details in the Transition chapter), there are huge uncontrolled rises in energy prices due to crisis’s or taxes.  A little more detail would have been good.

Energy production

We will still need energy.  Zero carbon Britain sees a totally renewable future with 770 TWh annual energy demand met by renewables (105TWh a year comes from heat pumps added onto the figure above).

source output (TWh/yr) details
offshore wind 530 140 GW maximum power,
14,000 turbines rated 10 MW
onshore wind  51  20 GW maximum power,
10,000 turbines rated 2 MW
wave power  25  10 GW maximum power
tidal (range and stream)  42  20 GW maximum power
solar PV  58  75 GW maximum power,
covering 10-15% of UK roof area
geothermal electricity  24  3 GW maximum power
hydropower  8  3 GW maximum power
 Total  738

In addition they visualise another 25TWh/year of renewable heat from solar hot water and 15 of geothermal heat used to heat buildings and the 105TWh from heat pumps. On top of this Zero carbon Britain looks for another 274TWh of biomass energy this is used to power a few vehicles, run some industries (for example cement needs large amounts of heat), heat some buildings and act as an energy storage medium to balance renewable supply with user demand.  This biomass is largely grown on land used for meat production, which is much reduced.

In my view.  Much to commend here.  If anything they are being conservative on the renewables, although as they point out if you added more you would end up with a surplus at some times of year and still end up with deficit at others.  It does raise some interesting questions though.  For example there are just under 4000 wind turbines of the size that disturb people onshore.  Its difficult to see this doubling in number with increasing resistance.  However, the slack could be made up by other renewables.

75GWp of PV seems on the low side.  I just wonder what to do when PV cruises past 75GW?  This is only 10-15% of the available roof space, although some of the other 85-90% is allocated to solar hot water.  I calculate from the projected heat output there would be 16-17 million such systems, most of the houses in the UK would have them fitted.  Of course my house has both and there would be a possibility of having both on many UK houses.  My biggest gripe with this section is over heat pumps.  Having looked into them for our book “No oil in the lamp” I’m not convinced they will work retrofitted into new buildings.  The problem is most forms of renewable heat systems won’t either.   Nor is a COP value of 2 any use.  The minimum such value is 4.  There is however some very interesting work on balancing out different renewables using 10 years of past weather data.  82% of the time using the Zero carbon Britain model the electricity supply is in surplus. The rest of the time they look to synthetic gas to balance out the deficit.

Transport

Zero carbon Britain (like our book) envisages almost all transport to be electrified.  The amount of electricity needed for this is large but manageable.  Dividing their figure for the electricity required in kWh by electric cars per person per year we get almost the same figure of about 1kWh per person per day.  This assumes no range increase.  They are negative about the hydrogen economy, as are we, but for different reasons.

In my view. The only questions I would raise is over supply of rare earths and the energy used to make the cars although they allow energy in their scenario for industry.

Landuse

Zero carbon Britain looks to a much lower consumption of meat.  I think this is right.  I’m trying to cut the meat down in our family.  They usefully indicate what the diet would look like in 2030.

Campaigning and what you can do

Very positively the report has some sections for individuals and campaigners on changing their own and other peoples lifestyles.

Conclusions

Despite my criticisms above I’m very positive.  The modelling on balancing out renewables is particularly valuable.  Its just a bit vague on how we are going to get there on demand reduction.  But for anyone interested in the kind of areas this blog is, its a valuable resource.

Neil

 

 

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2 Responses to Zero carbon Britain 2013

  1. Tobi Kellner says:

    Hi Neil,
    as the main author of the “Power Up” energy production chapter in ZCB I’m glad you generally liked our research.
    A few quick comments:

    As for the PV area, you’re right that there’s no hard physical reason for why we only have 75 GW of PV. Even if we stick to roof mounted PV we could physically have much more than that. The issue is one of diminishing returns: By just adding more PV capacity you end up increasing energy supply at times when you already have a surplus (day time in summer) while you don’t get more energy at the time when you need it most (dark winter days). Of course you can store it, but round-trip (electricity->gas->electricity) losses for long-term gas storage are >60%. There comes a point when adding another GW of PV capacity is a lot less useful than adding another GW of offshore wind (which produces, on average, more in winter).

    As for heat pumps, the first thing to say is that we’re short of alternatives. Even under the ambitious assumptions we make about energy demand reduction for space heating we still need an awful lot of heat energy, more than 250 TWh/yr. Geothermal and solar heat can’t provide this (unless inter-seasonal heat storage has a breakthrough), so it’s either biomass or heat pumps. The trouble with biomass is that in ZCB we assume that we’ll need huge amounts of biomass for other things (synthetic fuels, gas backup) so even with a very small contribution of biomass to space heating we have to fundamentally change land use to grow the biomass. So heat pumps are our best bet.
    We assume that they can physically be fitted into almost all buildings. Crucially, I would argue that “a CoP of 2 is no use, you need at least 4″ is true in a fossil fuel world but not when you’re on 100% renewable electricity.
    If I need three units of fossil fuel heat to produce a unit of electricity and then my HP only produces two units of heat from that kWh of electricity then that’s indeed of no use. But if I can turn a kWh of wind electricity into two kWh of heat then that’s a different story, especially if I can use wind electricity at times (e.g. middle of the night) when supply would otherwise exceed demand. For ZCB we assume that most buildings can be fitted with HPs (the rest uses biomass or direct electric heating), and that the average CoP (or rather: SPF) is around 3.0. But even if this value were only as low as 1.5 it would still be better than direct electric heating (SPF/CoP of 1.0).

    Best wishes,

    Tobi

    • admin says:

      Tobi,

      Thanks for your detailed reply. On the PV we are going to run into problems if we cannot do something with the power. Germany has already run into these problems. I have written a blog post about this and there are some solutions. The point is there will be a point at which PV will no longer require subsidy (probably within the next 5 years). Technically for largish 3-4Wwp system I would say we are there in that it will pay back in 25 years but the payback is till too slow for most people. What I was trying to get across was when PV no longer requires subsidy it will explode and will end with a lot more than 75GWp unless you ban people from fitting it, which I think would be outrageous.

      On biomass quite agree we cannot heat the UK using wood. I also see why people are so keen on heat pumps because as you say the alternatives are limited. My argument with heat pumps is not so much about where the electricity comes from. They are threefold

      1) a COP of 2 won’t heat a building effectively. For our book we looked at a church that been rebuilt in a very eco friendly manner. There heat pump couldn’t cope in the very cold winters we have been having. This technology requires having a very well insulated building.
      2) retrofit is very difficult. Firstly most gardens would not fit a slinky so you need a borehole. A friend at church looked into getting one. The installer was unwilling to use a borehole since in Edinburgh he reckoned there are lots of orphan pipes under peoples gardens. Our house would struggle partly because of insulation but also because these systems work best with underfloor heating. Whilst the ground floor would be fine there is insufficient space between the joists on the first floor to install this.
      3) Most reasonable sized systems need a three phase supply and grid reinforcement.

      Neil

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