How much energy do we actually use? Part II – A UK case study

 In the previous section I analysed global trends within energy, next I’ll take the example of the UK to illustrate how energy is used and what we can do to cut emissions.

Below is a Sankey Flow diagram (units in the form of mtoe), for the energy flow patterns within the UK (accounting for losses in the process). From this we can calculate that electricity, is just 20.1% of UK energy final UK energy consumption, while transportation fuels (virtually all oil accounts for 36%).

The low level of electrical use is important in the whole nuclear/wind energy debate. The nuclear lobby decry the “intermittency” of wind, ignoring the fact that they have their own problems with intermittency (i.e the grid demand varies but they can’t vary the output of Nuclear plants by much). But intermittency is only an issue for this 20.1% of energy use (and really only a small portion of that). As far as the other 79.9% of the UK’s energy use the intermittency issue is little more than a red herring, noting of course that certain renewables sources such as tidal, geothermal or hydro are not nearly as prone to such intermittency problems. Given the lower capital costs of renewables compared to nuclear , this largely blows the whole “nuclear debate” out of the water, as the only part of the energy grid where nuclear could be considered an option is roughly 30-50% of the electrical load, around 6-10% of our overall energy needs.

You will note how 27% of the energy outputs above go towards “domestic” consumption while a further 17% are related to “commercial” energy usage (slightly hidden in the bottom left of the figure). The DEPP report here, shows that space heating and hot water accounted for 82% of domestic use of energy (and see here for that also) and 64% of commercial use of energy as well as 15% of industrial energy being used for process heat generation. The bulk of these heating requirements would be those lines you see coming from the natural gas pile of the supply side. Thus by my calculation (adding up all the above) 36.8% of UK’s energy use is directly related to heat generation. I should note, I’ve seen other reports saying heating is closer to 45% of the UK’s energy needs , but lets not argue over the numbers, the fact is that our heating requirements are much larger than our electricity demand, and should thus be our prority.

We need some hot stuff

It may sound obvious but the easiest way to generate heat is with something hot. Using a thermal power station (gas, coal, nuclear, etc.) to generate heat which you then convert to electricity at a typical efficiency of 30-45% then transmit across power lines (95-90% efficiency), the convert it back into heat (70-85% efficiency typical)  to boil a kettle (or use it in storage heaters, etc.) is very energy wasteful. By contrast burning fuel in a boiler (or gas oven) and using it directly is much more efficient (65-90% depending on application). On a carbon footprint basis for the UK, electric heating works out at 0.527 kg of CO2/kWh  (this figure accounts for the 21% of UK electricity that is generated from low carbon sources) while gas fired heating works out at 0.203 kg of CO2/kWh, 2.6 times lower! This is why you’ll occasionally hear some engineers talking about the idea of banning electric heating systems (as Queensland in Australia is already looking at doing for hot water systems).

One easy way to make big savings in carbon dioxide emissions, is to firstly accept that the bulk of this heat energy is still going to come from fuels of some sort, largely natural gas in the interim. A process called Combined heat and Power (CHP) could easily meet these heating needs while offsetting our need for large power stations for electricity generation. 70-55% of the energy generated at these power stations is typically thrown away as waste heat. CHP is scaleable form the size of domestic boilers to large power stations and has been used on the continent for decades. Tri-generation also allows CHP to provide cooling in the summer months  . Longer term we could then swap these CHP systems over to run on biofuels (indeed some already do) or hydrogen derived from renewables, once they become available.

Unfortunately, for the nuclear lobby a good deal of the very energy wedge where CHP would sit forms the very same baseload electrical load that is their favoured energy niche. While nuclear can provide heat energy it’s not really practical given the large size of current reactor designs and their location far from cities and industrial centres. Relocating some of these loads to take advantage of this heat would be neither practical nor economic (once you factor in the costs of relocating as well as the radiological protection costs associated with operating next to a nuclear plant). If you ever wonder why nuclear lobbyist have a pathological hatred of CHP, this is why. If the CHP lobby have their way, there won’t be much of a baseload capacity left for nuclear to supply!

Of course we could also save a good deal of energy by better insulation and improving energy efficiency, further reducing our heat and electrical loads, and producing significant reductions in carbon dioxide. Which, unfortunately again for the nuclear lobby, would further cut into their narrow energy wedge.

As far as completely carbon free heat generation options go, solar thermal (hot water or air) is one obvious method given that it directly generates heat without any mucking around with electricity. And yes it can work well in the UK, indeed there are some who’ll tell you it works better in northern latitudes than southern Europe due to the longer days in summer and longer heating season in winter.

There’s also the option of geothermal energy, although that’s often location specific. Then there’s ground source heat pumps or air source heat pumps, thought I would urge caution with the case of heat pumps. They rely on using small quantities of high grade electrical energy (79% of which as noted earlier comes from fossil fuels) to generate large quantities of low grade heat energy (at temperatures of around 30°C). If you’re not careful they can become a net sink rather than a source and/or generate more carbon dioxide than they displace. There are also the practicalities of installation. Heat pumps, as noted, run at a lower temperature than conventional radiators can operate. So obviously only an option if you’re already planning to renovate a building and put in air-con or underfloor heating. And the low temperatures of heat pumps make it of little use to major industrial heating applications (we’re never going to run a blast furnace or a brewery off one!).

Assuming our figure of 36.8% above is accurate, and assuming we can cut our building heat load by 50% (ambitious but achievable I reckon), this reduces our heat demand by 28% (which includes lots of other heat loads as well) to roughly 26.5% of current energy use. Assuming we can meet say, 30% of this through completely renewable means (≈ 8% of current energy demand) and say, 40% with CHP, which (assuming a 3:1 power to heat ratio) would also generate about 17-30% of the country’s electricity (the exact % of the electrical load CHP picks up depends on the impact of those heating load cuts I mentioned and whether we implement Tri-generation or not) generating ≈ 15% of current UK energy demand. Even this modest program would reduce the country’s energy demand by around 30%, enough to remove all our large coal fired power stations and cut gas demand by 60% and we’ve not had to erect a single wind turbine or build one nuclear power station! Obviously if we now add in some modest (and thus achievable) renewable energy targets, include some moderate energy efficiency measures (to cut electricity use) and combine CHP with CCS, a 50% cut in CO2 emissions in the medium term future is a realistic goal (and without us all having to becoming hippies either!).

Movin down the road

This brings us to transport fuels, representing roughly 36% of UK energy usage. Nearly all of this currently comes from oil, which in a post peak oil world is not going to be sustainable. Some of this can be met via electricity in various forms of generation, notably by using trains more. The French, Japanese and many other countries have large and efficient networks of electrified high speed railway lines, thought of course the down side is that in order to utilise electricity we’d need to first complete electrification of the whole of the UK rail network (and replace all the engines, rolling stock, etc.) and presumably upgrade the existing network to high speed too.

And the woes of railroad electrification pales in comparison to the difficulties we’ll face with electrifying cars and other road traffic. I have to confess, much as I’ve been an enthusiast of the electric car, I’m not convinced it can deliver the sort of performance that is sufficient for us to consign the IC engined motor vehicle to the dustbin of history (yet!). Yes, we can use electric vehicles to perform many duties, such as travel within urban areas (cargo and people). The vast majority of car journeys are only a few miles (commute to work, down to the shops, etc) and electric cars can easily manage this. But long range journeys across the UK (never mind the vast distances of the USA or European continent) are out of the question, at least with presently available battery technology. This report regarding the Beeb’s efforts to get an electric car from London to Edinburgh underlines my concerns.

And if electric cars are stretching things, electric trucks? electric ships? planes? You got to be kidding me! The bulk of these will need to be powered by fossil fuels in the interim, while we work out a sustainable alternative. Biofuels are one idea, and yes I know I had a go at them earlier, but so long as we downsized our use of such fuels to the minimum level possible and accepted a certain level of cycle in-efficiencies it might work out as acceptable. One could see a system where by we use electrically powered vehicles (or better public transport) in towns and hire a rarer IC engined car for the occasional long range journeys of the public transport network.

Indeed, once you consider the maintenance costs of electric cars and their battery systems, and the lengthy charge times, we might even need to question whether the whole paradigm of individually owned automobiles is shortly to become an obsolete concept (best not mention this to Jeremy Clarkson 😉 . We could see a future where none of us own cars, but simply rent them (electrical or petrol) depending on our needs. There are already systems in several EU cities where you can rent a bike via your phone, cycle to your destination, then lock the bike and walk away. Could we one day see a similar system operating with cars?

Alternatively there are hydrogen fuelled vehicles, though of course again we’d need to accept certain cycle in-efficiencies here (i.e the conversion efficiency of making, transporting, storing, and then using hydrogen, plus what you loose in leaks along the way) and face the thorny question of where this hydrogen comes from, remembering we may need to divert some of this to keep the CHP systems mentioned earlier running in future once gas supplies start to waver. Renewables would be an obvious answer as a power source, but we’re talking about an awful lot of them, and it would take sometime to install it all (nuclear is out of the question on this point because of its slow build rate and high capital costs). Even then there’s the infrastructure issues. Do you have any idea how many petrol stations there are in the UK?….11,027 according to this link. It would take a considerable period of time to convert them all to run off a gas based fuel rather than oil. Granted, it would be easier than converting them all over to service electric vehicles, but we’re still not talking about something that we can sort out over a long weekend.

What’s good for the goose is not good for the gander

Of course not every country has the same energy loading arrangement as the UK. Northern European countries have a much higher demand for heat in winter (hence why they’ve taken to using CHP much more than anywhere else) while in southern Europe electricity demand in summer is much higher, due to the needs of air conditioning systems (thought as noted this could be met using Tri-generation or various solar cooling systems). Even so, the heating needs of southern Europe would surprise you.

I recall a conversation I had with a European hotel owner in which I boldly stated that the peak in energy demand in the Mediterranean countries was obviously in the summer due to air-conditioning needs. He corrected me and pointed out that, no there’s a heavy energy demand here in the winter too, higher in fact than the demand for energy in the summer! Mediterranean houses are designed to resist summer heat, not cold winters. Also people are more inclined to take hot showers in winter than in summer. Then there’s the increased demand for electric lighting in winter, as well as TV’s and entertainment systems (because people are more inclined to stay in).

Indeed even looking at a similar Shankey diagram above (from the SEAI) for Ireland, we can see that despite being right next to one another Ireland has a slightly different energy consumption rate. For example, 42.8% of Irish energy use is transport related, against 36% in the UK, with a per capita consumption in the UK of 0.96 toe (59.8mtoe /62m people) and Ireland (5.685mtoe/4.47m people) 1.27 toe, roughly 25% higher. Even thought Ireland is a smaller country it uses both more energy per capita and a share of its overall energy consumption on transport. Our poorer public transport may have something to do with this thought, so improving public transport in the country would be an important priority. 21% of Ireland’s energy use is domestic (again a large portion of this would be heat), less than the UK, while industry is 20.3% of our energy demand, while it’s slightly higher than the UK at 19.2% (1.7+30/164.9 = 19.2). Clearly, despite the similarity of the two countries, there are differences in energy use patterns, so you can imagine the difference if we repeated this exercise between, say Canada and Thailand.

Joined up thinking

Either way, it’s important to put our energy use, globally, nationally and locally, in the right context. Proposing large megalomaniac scale arrays of nuclear plants in the UK  would do little to solve anything, other than to furnish the egos of certain nuclear energy supporters. But equally a policy of wind, wind and yet more wind, isn’t going to work either, not if we tie them all up to the grid as its currently wired up. Beyond a certain point we run into problems with balancing the gird. And no, nuclear can’t be used to back up wind, its not able to undergo the sort of sharp load cycling that the grid demands. Only thermal (fossil fuels) power stations or hydro-electric or various energy storage options can cope with this. So it might even be sensible to simply build wind farms in future with no grid connection, instead dedicating them to hydrogen production or shunting the power into some alternative electrical grid for running loads that are not “on demand” critical (such as recharging electric cars).

Either way, there is an urgent need to explore other renewable energy sources and diversify, solar thermal can be very useful due to its ability to directly generate heat (the very source of energy we principally need), tidal energy has the advantage of being regular and predictable. Both PV and wave energy are rapidly approaching maturity and economic viability. While I’m certainly no fan of biofuels and biomass (no! really?) they have certain unique advantages that can’t be ignored and there is thus a need to invest in them also (just so long as we don’t go crazy, we need that farmland to grow food as well!).

Unfortunately, all the concepts I’ve explored here require long term planning to implement. The capital costs would be high, not just the energy systems themselves, but the infrastructure to support them (so forget about “the magic of the market” paying for anything!). Our entire energy distribution system is geared towards fossil fuels and turning around this juggernaut is going to take a lot of time, money and careful planning. And time is a commodity we may not have an for very much longer, not if the Hirsch report on peak oil is correct or indeed the IPCC’s latest assessments on global warming prove to be accurate.

In short, before we come up with and answer to the ultimate question (be it to life the universe and everything or how do we deal with climate change?) you need to first understand the question, otherwise the proposed answer (42…windfarms?) wouldn’t work.

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About daryan12

Engineer, expertise: Energy, Sustainablity, Computer Aided Engineering, Renewables technology
This entry was posted in clean energy, climate change, economics, energy, nuclear, peak oil, politics, power, renewables, sustainability, sustainable, Uncategorized. Bookmark the permalink.

23 Responses to How much energy do we actually use? Part II – A UK case study

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  5. John ONeill says:

    ‘though’ rhymes with ‘know’
    ‘thought’ rhymes with ‘short’
    Just thought you should know

    • daryan12 says:

      Ah! Good to see the Grammar nazi’s are still out in force 😉

      Yes, this is the hazard presented by spellchecking software. My personal favourite, I know someone called Ishai and the spellchecker keeps trying to call em “ashtray” which I have to watch out for …. I don’t think she’d see the funny side of it!

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  8. chris nelson says:

    I tend to think of myself of someone who is average in the UK with their energy consumption and I worked out with commuting to work and normal living etc I was consuming 13Kwh. Thats 4745Kwh a year just for me. 295.6Twh a year if I took that as the ave for this country alone and that does not take into account businesses, government uses etc. Then I had a thought, what does that equate to in nuclear power stations? Now I know my maths are probably way off, but I checked and checked and it still came up with a colossal amount of stations. If an Ave plant produces 12 billion Kwh a year, then we need 24602 plants. So I thought that cant be right, that’s ridiculous until I found out the existing 10 plants we have produce 6% of the nations power. But that would mean we only need 166 plants to supply 100% so surely something is wrong here.

    • daryan12 says:

      In terms of final energy consumption the UK is 164.6 mtoe, which given that 1mtoe = 11,630xe9 kWh’s => 1,914 Billion kWh’s for the whole country (3,877 Billion kWh’s of initial energy inputs before any losses are accounted for), so that works out at 30,870 kWh’s per person per year, or about 84 kWh’s per person per day, with power (i.e. electricity) being about 20% of that.

      It is important to differentiate between “power” i.e. electricity, and overall energy consumption (electricity plus everything else). I recall the EPR output (1600 MWe reactor operating at a 90% capacity factor) pumps out 12.6 Billion kWh’s (so pretty much bang on you’re estimate), so to just meet UK electricity demand with the we would need: (1914e9 x 0.2)/12.6e9 = 31 plants or about 154 to do everything, so you might be a little off somewhere yes.

      However, the figures I give above belittle the situation. Electricity demand varies considerably over the day, spiking in at certain times (typically around 4-5pm or at then end of a popular soap opera), then falling back alot at other times. There are also seasonal variations between summer and winter, with winter energy consumption being much higher (up to 50% higher in the UK). Nuclear reactors like to be on all the time, so they alone couldn’t really cope with such swings, not least because you’d need to probably double or triple the figures I gave above (or more!) and most of those reactors would spend a good deal of their service life idle, only being turned on for a few hours each day, or over the winter. The French get around this loophole by buying and selling electricity from their neighbours. But I doubt two neighbouring countries could try pulling the same trick.

      Ultimately nuclear once it went over about 60% of electrical output (or 12% of overall energy demand) would face the same problems as renewables – then need to “bunker” energy in some form (hydrogen I assume) to cope with the peaks and troughs in demand. Further, once we start to factor in cycle efficiencies (e.g. electrolysis is only 70% efficient and a car’s IC engine about 33% efficient so you need 1/(0.7*0.33) = 4.3 times the energy to do the same job, greatly increasing yet further the number of reactors quoted above. Given that per kWh renewables (such as wind, hydro, biomass and increasingly solar) are already cheaper than nuclear, it would make sense to use them for the role of hydrogen manufacturing.

      This is also why I favour trying to match demand with supply. e.g. You want to heat you’re home? well firstly insulate it well but then look at using a biomass boiler, CHP unit or solar thermal unit to heat it. A long distance plane? probably best done with Biofuels or hydrogen. Short range commuter car or bus? probably best done with electricity charged from a HVDC connection. A policy of nuclear, nuclear and yet more nukes simply won’t work. Nor indeed will wind, wind and yet more wind, not without the support infrastructure (hydrogen production & distribution, a HVDC grid, etc.) to tie everything together. And that is where I fear the future energy bottle neck lies.

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