The Sun Never Says “You Owe Me”

In celebration of Earth Day 2015:

Imagine some space travellers arriving in orbit around Earth. They start surveying for life-forms, signs of habitation, transport, communications..etc. You know, the sort of thing that the Enterprise and Voyager crews do routinely before they beam down to the surface and make contact. πŸ™‚



So what do they see as they orbit us? They see lots of evidence of an intelligent life-form. OK they might review that impression of intelligence after they look at some of our TV shows. But still it proves that some of our species were intelligent enough to discover and understand the laws of the Universe. And obviously since then we’ve applied that understanding to make our lives a lot more comfortable and enjoyable than when we were living in damp caves without any light or heating. Mind you, these space travellers might revise their impression of intelligent modern humans again when they realise that we don’t take much care in looking after the interests of other species, even the very intelligent ones, in fact especially the more intelligent ones when you think of cetaceans and other primates. (And, if you remember, we have to rely on the Enterprise crew to travel back in time to rescue our last great whale and hence save the planet in the future. What, you didn’t see Star Trek IV – The Voyage Home ?)

But they do see a very beautiful planet. Obviously it’s fantastic place for the evolution of life in myriads of forms. Oops, their opinion of us has diminished some more cos they’ve just tuned into the God Channel and listened to one of us proclaiming the idea that we didn’t evolve, we originated as an idea in God’s Mind subsequently brought into being with a couple of handfuls of dust and – for some of us – a rib. Still, by now their Scientific Officer has probably had a look at the Natural History Museum website and seen the Darwin Gallery so they know we’re not all as daft as that.

And they also see that our lovely planet Earth is in the Goldilock’s Zone (or whatever the little girl who visited bears was called in their fairy tales). We’re pretty well set up here. Not too hot, not too cold, just right.

And – we have millions of kWh of energy pouring down on us every day. And the sun never says “You owe me.” Or “I want a return for my trouble.”

Planta Solar 10 power station near Seville (ref3)

Our daily worldwide consumption of electricity

Been doing a little bit of reading around the subject. (See ref 1 below.) Our current daily worldwide consumption is 12 Terrawatts. A Terrawatt is 1,000 million Kilowatts. The proportion of incident solar energy which reaches the ground, averaged over the entire globe is 164 Watts of energy per square metre per day. The entire planet receives 84 Terrawatts of solar power in a day. It’s reliable. It’s clean in terms of atmospheric pollution. The sun never says to us “You owe me”.

OK, only a proportion of the 84 Terrawatts is recoverable. But a considerable amount of it is. Especially in deserts where, let’s face it, not a lot else is happening. We have the technology to harness this energy, to use it, share it on electricity grids. And what are we doing? We’re still digging up coal. Drilling for oil. Developing Tar Sands, the Arctic, deep-water rigs, fracking. The waste products from burning fossil fuels are driving up CO2 levels in our atmosphere, climate change is becoming more and more observable. Not to mention the other by-products of fossil fuels which clog up our lungs. Those with vested interests in this fuel status quo tell us – through very well financed ‘think-tanks’ and lobbyists – not to worry too much about climate change scare stories. That’ll be those ‘scare stories’ disseminated by the 99% of climate scientists worldwide who agree that climate change is happening and that human activity is a significant aspect of what’s driving it. We know all this. But …

One of the delights of living in Scotland is that we have a government which has been driving forward its energy sustainability targets and renewable energy research with almost evangelical fervour. Hurrah! They publish “2020 Routemap for Renewable Energy in Scotland”. Prior to August 2011, the Scottish Government’s committment was to ensure that we meet the EU’s renewable energy target of 20% of energy from renewables by 2020. This went beyond the legally-binding 15% renewables target that the EU set for the UK under burden-sharing arrangements and showed the higher level of potential and greater ambition for renewables in Scotland. But…. since then….

Scotland’s Renewables Ambition and Paths to Delivery, Aug 2011 – Extract (paraphrased from Ref 2)

Because the pace of renewables development has been so rapid in Scotland, with the nation now on course to exceed its milestone of 31% of electricity demand to be sourced from renewables by the end of this year, 2011, we can now commit to a new renewable electricity target.

Our new target is to generate the equivalent of 100% of Scotland’s own electricity demand from renewable resources by 2020. Increasing our target for renewable electricity means that we are also able to increase our overall renewable energy target. We are now aiming to meet at least 30% of demand for all our energy from renewable sources by 2020.

Scotland’s 100% renewables electricity target is the most ambitious in the European Union. Meeting it means that, together with our 11% renewable heat and 10% renewable transport targets, Scotland’s overall share of renewable energy will be at least 30% by 2020. Scotland’s target is on a par with that for Denmark (30%), Portugal (31%), and considerably higher than Germany (18%), Ireland (16%), Spain (20%) and France (23%). And our ambition is clear – that with the largest offshore renewable energy resources in the EU (25% of EU offshore wind; 25% of EU tidal; and 10% of EU wave power), Scotland will be making an even greater contribution to the EU’s overall target than our population size.

In our house, we’ve decided to help that target along with a modest addition to our roof. We’ve had a 3kW array of solar photovoltaic panels installed. It’s not a huge house but fortunately it has two sections which face south-ish and we’ve got six panels on each of those.

Me being me, I have a solar electricity spreadsheet set up.  πŸ˜‰  The amount we save is made up of

  • Generation Tariff: the UK government Feed-In Tariff (FIT), 15.44p for every kWh we produce irrespective of whether we use it in the house ourselves or not;
  • Export Tariff: Payment to us from our energy supplier for surplus electricity which is fed into the National Grid. Small scale installations are assumed to feed 50% of their production into the Grid and are paid 4.5p per kWh. This 50% assumption probably works in our favour as we’re both at home during the day and using more than half of the generated electricity.
  • Smaller electricity bills.

Our heating and hot water is from our gas boiler. So most of our energy costs are gas. But I reckon that the income stream from the solar panels will reduce our total energy costs by at least half. The Tariff payments continue for 20 years. It’ll take about half of that to cover the cost of installation. The rest is ‘profit’. I noticed that the solar company people talked as much about the economics of it as a good investment as they talked about the benefits in reducing carbon footprint.

This is the month-by-month electrivity production (KwH) since we started in March  2013 along with the cumulative savings it represents.

solar savings  .

Ref 1): Univ of Oregon notes on the Basics of Solar Energy

Ref 2): 2020 Routemap for Renewable energy in Scotland

Ref 3): Planta Solar 10


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