I put this together in order to better understand the whole energy/global warming/emmisions thing and what the green energy solutions and possibilities were.

• From the DTI white paper “Our energy future - creating a low carbon economy” it appears that electricity generation is not the big culprit really.
  • Transport (35%) and
  • Space Heating (26%) are the two biggest.
• Add in water heating (8%) and you have a total of 69%!
• Click the thumbnail for the chart (75KB)
• Of course, since fossil-fuel generated electricity is only 30% efficient, any replacement of this with renewable electricity will triple the reduction of energy used to generate the electricity. This of course means even less pollution and greenhouse gas emmissions.

What I'd also like to know are…

• What proportion of transport is air travel (see Transport Energy below)
• How best to tackle space heating (see Reducing energy use below)
• How are these proportions predicted to rise in future

The Royal Commission On Environmental Pollution's 22nd Report: Energy - The Changing Climate is a useful reference, though at times a little vague.

• It was done in 1999 I think, but still has relevant data.
• Their most important conclusion was that we have to reduce energy consumption by some 30% by 2050.
• Otherwise we have no hope of preventing climate change.
• See Reducing energy use below

Current UK Electricity generation requirements are approx 50GW (5×10^10W).

I derived this as follows…

• From Supply. Electricity supply and consumption (DUKES 5.2}, total electricity supply for 2003 was approx 400,000 GWh (4×10^14Wh).
• There are 365×24 hours in a year, so 4×1014 / (365 x 24) = 45×109, or 45GW.

A few basics for those of us who may have forgotten our 'O'-level physics…

• Electrical power is measured in units called Watts (W)
• Electrical power is actually a rate of energy use, i.e. the amount of energy used over a length of time.
• The standard unit of energy is something called a Joule.
• 1 Watt = 1 Joule per second
• So your 15W low energy bulb (all your bulbs are low energy aren't they?…!) uses 15 joules of energy per second.
• The total amount of electricity supplied over 2003, quoted from DUKES 5.2 above, was 400,000 GWh (GWh = giga watt hours). This is a measure of energy, since it is power multiplied by time (Wh = Watts x hours)

Here's my summary, derived from the subsequent sections. It shows what might practically be acheived in the next 10 years or so for electricity generation…

How much power do wind turbines generate?

• Ecotricity use Enercon turbines.
  • The larger of these generate 2MW and 4.5MW respectively per turbine.
  • These seem to be typical numbers
• According to the British Wind Energy Assoc (BWEA],
  • we current generate about 800MW with wind power in the UK today.
  • this is 0.6% of our electricity supply they reckon.
  • I make it 0.8/45 = 1.8%, so either the 45GW number is wrong, or more likely, due to wind fluctuations, wind turbines produce an average power much less than there max (reasonable).
  • According to BWEA, wind turbines will produce about 30% of the energy over a year that they could if they were spinning optimally 100% of the time.
  • So my 1.8% scales almost exactly to 0.6% with this 30% factor.
• 7GW offshore turbines are planned (see below), so to take the total to 10GW (a nice round number) would require another 2.2GW onshore. This is about 1000 2MW turbines. There are currently 1100 turbines, many smaller (older), so this is not unreasonable.
  • With a 30% load factor, this 10GW translates into about 6% of requirements. Not that enormous, but still environmentally beneficial.
  • In fact, it's worse than that, since the higher the proportion of electricity generated by wind, the more dramatic the effect of intermittent supplies is. At 15.6GW max capability, we can only rely on 2.9GW, 18%, according to BWEA.
  • So actually our 10GW will produce about 2GW of power we can assume to rely on.

Offshore wind power:

• According to BWEA,
  • There is over 1 GW of projects with planning consent waiting to be built, and
  • a second round of offshore tenders from the crown estate with a total of 7.2 GW waiting for applications, equivalent to 7% of UK supply.
• BWEA have a very nice picutre of the the potential of offshore wind here
• Expense is not necessarily higher (final net expense unclear)…
  • “Marinising” the turbines typically adds about 1 - 2% to the cost (corrosion prevention, more expensive foudnations)
  • The cost of the cable connection may also be more expensive (not always the case when compared to remote upland sites).
  • Operation and maintenance costs may be increased and there may be a risk of lower availability due to difficulties in obtaining access to the wind turbines during bad weather. However, this has not been borne out by experience at Vindeby and Tunø Knob.
  • Reduction in the civil engineering costs due to the absence of access roads.
• Interestingly, mean wind speeds are higher on British uplands than offshore. So offshore is not necessarily better for us, though it is for a flat country such as Denmark.

Wind Costs:

• According to BWEA data, onshore electricity costs are comparable to CCGT (gas) and coal.
  • actually less than coal if “cost of carbon” is included.
• Offshore is more expensive than coal and gas
• Nuclear is, surprise surprise, woefully uneconomic. And it doesn't included decomissioning and disposal costs.

Ocean Power Delivery (OPD] is one UK company that makes wave energy converters.

• Individual convertors (as recently started in Portugal) have similar output to wind turbines.
• OPD reckon a typical 30MW installation would occupy a square kilometre of ocean.
• So to produce something similar to the wind turbine plans of 10GW, requires some 340sq kilometers. Spread around the coastline of many thousands of miles, this seems perfectly reasonable.
• Again, load factors are about 30% (according to BWEA), so this amount would produce another 6% of electricity we could rely on.

• 1.5GW of electricity is generated by hydroelectric plant according to this page
• They reckon this is 2% of our total. With a load factor of 50% (BWEA figure) I make this 0.75/45 = 1.7%
• This is pretty much fixed: though it's clean, we don't want to go round damming up any more of our valleys.

Barrages

• At La Rance, France, a 240MW plant has operated since 1966.
• According to this energy resources page, There are eight main sites around Britain where tidal power stations could usefully be built, including the Severn, Dee, Solway and Humber estuaries.
• Although the energy supply is reliable and plentiful, converting it into useful electrical power is not easy or cheap.
• Barrages (aka dams) are very expensive and have huge effects on eco-systems.

Alternatives are Marine Turbines…

• Marine turbines, aka submerged wind turbines. See this write-up
• Predictable, though not continuous (no power when tide turns). Assume 10 hours per day.
• Much cheaper than a barrage
• These will generate about 1MW each. Installation of 10-20 in small farms.
• So for 1GW say, at a load factor of 40%, we'd need 2500 dotted around the UK. This is probably feasible as we have a coatline of many 1000's of miles.
• Another company, Blue Energy, reckons you could build large scale “tidal fences” generating GigaWatts.
• An obvious trick was missed in not building these sorts of things into either of the Severn crossings.

According to this ECO Centre web page

• The DTI have estimated that solar panels installed on buildings have the potential to provide all the electricity that Britain currently uses, however that would mean photovoltaics on most south facing roofs which is unlikely in the near future

From their figures, I make the following calculations…

• It is reasonable to install 500W generating solar panel on a roof (about 5 sq m)
• ECO centre reckon 1KW installation will produce 700kWh over a year.
  • This averages at about 100W over the year.
  • So our typical house roof would average 50W over the year
• So if 1 million houses installed it, we'd get some 50MW. Sadly, this is small beer, just 0.1% of the 50GW total consumption in the UK
• Of course, it could be fitted to all other building roofs (offices etc), but we need about 100x improvement, which just isn't going to happen.

According to DUKES 1.1-1.3 Aggregate energy balances

• Air Transport used 12 Mtonnes oil equivalent
• Road transport used 42 Mtonnes oil equivalent
• Rail transport used 374 Ktonnes oil equivalent
• So Air Travel uses about 20% of the total energy of transport and is doubling every 6 years (see below).

According to DUKES 1.1.5 Final user consumption fuel consumption between 1987 and 2003 increased…

• by nearly 2x for air transport (6.5Mtonnes → 11.9 Mtonnes oil equiv)
• by about 20% for road transport (34Mtonnes → 42Mtonnes oil equiv)

Questions:

• How is air transport calculated - is it fuel at takeoffs?
• How does road transport split out - what proportion are
  • lorries?
  • car commuting
  • car commercial
  • car domestic & pleasure
• I assume there is a one-one mapping of greenhouse gas emmisions to oil tonnes
  • is this correct, or are aircraft emmissions worse, perhaps cos they're higher?
  • how do you quantify greenhouse gas emissions? Methane is worse than CO2 for example, so is there a 'temperature rise' weighting that's worth the effort?

FOE comments on what the Government should do are in "What the Government should do to tackle climate changeFriends of the Earth's response to the Climate Change Programme review". There is a bunch of stuff here for 'experts'

There's an interesting comparison of energy use per mode of transport from West Wales Eco Centre page. Cick the thumbnail for the comparison table (33KB).

From The Royal Commission On Environmental Pollution's 22nd Report: Energy - The Changing Climate we can reduce energy consumption (and need to!) by

• building regulations: make houses more efficient
  • can also offer stamp duty reductions to buyers who improve energy efficiency (difficult to implement in practice though!)
  • I also think every new house could be built with solar water heating and electricity generation _ I also think that dramatic tax incentives for all home inslation, solar water heating etc would have some effect. Current incentives are poor.
  • perhaps each new estate could have it's own wind turbine, or local small scale combined heat and power generator that also heats these homes
  • Building regs must also apply to offices, shops, factories.
• Combined Heat and Power for generating electricity and heating local buildings
  • these require lots of smll scale developments, which impact the way the national grid is currently designed (it currently assumes fewer massive generating facilities)
• Massively improved public transport
• Fuel cells for cars
  • and taxation incentives to reduce emmissions
  • But this only works in conjuction with reducing road traffic miles travelled. Otherwise vehicle efficiencies are balanced by increased vehicle use!
• Taxing Aviation fuel
• Car use taxation: road use charging, car parking tax, amongst others.

The RCEP have a table on potential for energy saving. Click the thumbnail to see it

Jon B

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