In this second part of my essay on Energy and Mankind I look into:
- The origins of usable energy on Earth
- Energy stores and energy flows in relation to human behaviour
- Energy quality
Part 1 of the essay is here.
Origins of Usable Energy on Earth
All to often it is erroneously assumed that all of the energy on Earth is derived from the Sun. In fact, a significant portion is derived from the supernova precursor to our solar system. All of the heavy elements on Earth, including uranium and thorium, were created in that supernova which is, therefore, the parent of all nuclear power. Natural radioactivity, mainly from the decay of uranium and potassium isotopes, also gives rise to the heat within the Earth, the source of geothermal energy. This heat engine also drives plate tectonics, without which we would have no mountains or hydroelectric power.
Figure 4 The Sun and the supernova precursor to our solar system combined provide most if not all the energy available on Earth that is used by Mankind and other animals and plants.
Tidal energy is derived from the rotation of Earth on its axis and the orbits of the Earth-Moon and Earth-Moon-Sun systems. This angular momentum is also inherited from the condensation of matter from the Supernova. The periodicity of supernova energy flows is more regular and predictable than solar energy flows that are controlled by haphazard weather and in this regard tidal flows are much superior.
Solar energy comes in two main flavours, 1) fossil energy stores comprising the organic remnants of ancient plants and animals that have become concentrated into ore grade deposits by geological processes – coal, oil and natural gas, and 2) renewable energy flows – wind, wave and solar power. Hydroelectric power, the Rolls Royce of renewable energy, is unique in that land forms created by plate tectonics provide the stores (reservoirs) at elevation providing the gravitational potential energy to convert rain water to electricity.
Energy Stores and Energy Flows
The concepts of energy stores and energy flows are fundamental. From the outset, Stone Age Man used fire when it was needed, not when it was coincidentally available. This was made possible by the solar energy stored in wood. As human societies have evolved and become more complex, using energy when it is needed has become imprinted on individual behaviour and on society as a whole. Man has only rarely harnessed stochastic energy flows, for example sailing ships and drying hay and clothes. Human development is dominated by the use of energy stores. And herein lies the crux of the whole of today’s energy debate.
The pattern of human society’s energy use is best illustrated by the pattern of electricity demand. This varies from country to country. Figure 5 shows what it looks like in the UK. There are 3 major cycles 1) daily, 2) weekly and 3) annual. Over a 12 month period, peak demand is always going to be around 6pm on a weekday in winter and the minimum demand is always going to be around 6 am at the weekend in summer. In 2009, peak winter demand was 2.6 times greater than minimum summer demand. Figure 5 is a picture of human individual and societal behaviour. Our electricity delivery system, that underpins our health, wealth and prosperity, must have the reliability and flexibility to match this pattern of demand. This is achieved almost exclusively through use of a range of energy stores. The more I think about it, deliberately introducing expensive stochastic noise into this finely balanced system seems quite insane.
Figure 5 The pattern of electricity demand in the UK, January and July 2009. Note daily, weekly and annual cycles. This is a picture of human individual and societal behaviour. We sleep at night, we work less at weekends and we require more heating in winter time. The electricity grid is the foundation of our modern society and economy providing security and comfort at multiple levels. The grid must deliver the exact pattern of demand to sustain that level of security and comfort. It may one day be viewed as an act of vandalism to place a large, expensive source of stochastic noise on that finely balanced system.
Figure 6 details a number of variables that combine to define the quality of various energy sources. What has happened in recent years is that Green lobby groups have persuaded everyone that environmental externalities trump all other aspects of energy quality which we will learn someday is a huge mistake. Especially since, renewable energy devices and their deployment are not without environmental externalities themselves.
Figure 6 8 different measures of energy quality are listed, These can be combined in different permutations to characterise the utility of different energy sources which will vary depending upon the use one has in mind. For example, natural gas is superior to gasoline in terms of energy density per Kg. But is not favoured as a transport fuel since its energy density per unit volume is much lower. The same applies to hydrogen. To compress these gasses to increase their volumetric energy density requires pressurised vessels, adding cost and increasing risk. A stochastic renewable source like wind only scores on the last three of the measures listed.
When I first became engaged in this energy debate it was from the angle of energy availability linked to the concept of peak oil. While there is an abundance of commentators who scoff at peak oil these are matched by those who still see global shortages (± catastrophe) around the corner. What happened in the period 2002 to 2008 was scarcity pushed up the price of oil. This higher price boosted supplies of expensive oil (albeit with time lags), reduced demand and encouraged efficiency. For those who cannot afford to fill their tank with gas, peak oil has already come and gone. Availability, scalability and cost are important considerations for any energy supply.
Last year I conceived and co-organised an energy conference in Edinburgh and in the opening address I used the history of naval warfare to illustrate the concept of energy quality (Figure 7). In 1911, Winston Churchill famously made the decision to convert the Royal Navy from coal to oil fired steam. He did this because oil offered many advantages over coal. It was more energy dense giving oil fired ships greater range and speed. And it could also be pumped through pipes, dispensing with the need for hundreds of stokers. On the negative side, the UK did not know then that it had indigenous oil supplies and this created a long term dependency of the UK on oil from the Middle East. Our superior navy would guarantee the security of these supplies. Chrchill did not give a toss about oil producing less CO2 than coal when it was burned. If Churchill was alive today (his grandson is, and made this speech to the Scottish Parliament) and was in charge of energy policy, what direction would he go in – wind or nuclear power?
Figure 7 A brief history of naval warfare and propulsion systems. The nuclear powered Nimitz class carrier is one of the most powerful weapons systems ever developed.
The pinnacle of naval power was reached with nuclear powered Nimitz class aircraft carriers that fly oil powered jets and with nuclear powered Trident class submarines armed with nuclear weapons. It has been put to me before that modern wind turbines have little in common with their historic counterparts. But let’s be serious, would any sane person want to go up against the Nimitz or the Bissmark in a sail boat? Our electricity supplies are of even greater importance to our security than our navy. It makes no sense to hobble this with expensive, stochastic wind power.
An examination of the quality variables listed in Figure 6 shows that wind only scores on three points 1) scalability, 2) environment (depending on one’s perspective) and 3) ERoEI. I have said this many times before, grid-scale, affordable and efficient storage is a game changer for renewables. Nuclear scores on all 8 points with the possible exception of environment, again this depends on one’s perspective. Nuclear in fact has extremely high scores on measures such as 1) density, 2) storability, 3) intermittency and 4) availability. Wind was used in the 19th and preceding centuries when our demands were much less. In terms of energy quality, nuclear power is the only option to compete with oil and I hope this explains to some readers why I strongly favour nuclear power over wind.