# David MacKay's powerpoint slides

On Thu 4/7/2013 I started this page as a place to collate powerpoint slides; I don't use powerpoint very much myself, so this is not at all a complete repository of my presentation materials; initially this page contains the figures from a couple of journal papers.

## Figures from MacKay (2013a)

Could energy-intensive industries be powered by carbon-free electricity?
Published 28 January 2013 doi: 10.1098/rsta.2011.0560 Phil. Trans. R. Soc. A 13 March 2013 vol. 371 no. 1986 20110560

The UK's primary energy consumption (a) in national units and (b) in per capita units. Electricity production (which is derived from roughly one-third of the primary consumption) is also shown.

Power consumption per person versus population density in 2005. Point size is proportional to land area, except for areas less than 38 000 km2 (e.g. Belgium), which are shown by a fixed smallest point size to ensure visibility. The straight lines with slope -1 are contours of equal power consumption per unit area. Seventy-eight per cent of the world's population live in countries that have a power consumption per unit area greater than 0.1 W m-2.

[See also David MacKay's Map of the World]

(a) Power per unit area of UK wind farms versus their size. The horizontal scale is logarithmic. (b) Power per unit area versus turbine diameter. The horizontal scale is logarithmic. The black curves in (b) show the trend that would be expected (within any single region) on the basis of the rule of thumb 'doubling turbine size increases wind-speed by 10% and increases power by 30%', and assuming wind turbines' spacings are proportional to their diameters. See appendix A for the methodology behind these data.

Capacity per unit area (left axis) and estimated power output per unit area (right axis) of US wind farms versus commissioning date. For the right axis, a load factor of 42% is assumed. Point area is proportional to capacity; the largest farm shown, Horse Hollow, has a capacity of 735 MW. According to Gallman [ref 3], Horse Hollow has an average power per unit area of 1.55 W m-2.

Electricity generated from nuclear fission versus time in a few regions, in (a) national units and (b) per capita units.

Electricity generated per capita from nuclear fission in 2007, in kWh per day per person, in each of the countries with nuclear power.

(a) Wind capacity per area, and (b) wind capacity per person, for several countries. Both vertical axes have logarithmic scales. (Note that to estimate the average power generation from this wind capacity one must multiply by the load factor; load factors for wind range from about 20% in Germany to 42% in the biggest farms in the USA.)

Four ways of delivering 16 kWh per day per person in the UK.

Red Tile wind farm, East Anglia, and its associated land area. The grid's spacing is 1 km. Each turbine has a diameter of 82 m and a capacity of 2 MW. Map Crown copyright; Ordnance Survey.

## Figures from MacKay (2013b)

Solar energy in the context of energy use, energy transportation and energy storage
Published 1 July 2013 doi: 10.1098/rsta.2011.0431 Phil. Trans. R. Soc. A 13 August 2013 vol. 371 no. 1996 20110431

Variation of average sunshine with latitude and with time of year. (a) Average power of sunshine falling on a horizontal surface in selected locations in Europe, North America and Africa. These averages are whole-year averages over day and night. (b) Average solar intensity in London and Edinburgh as a function of time of year. (Average powers per unit area are sometimes measured in other units, for example kWh per year per square metre; for the reader who prefers those units, the following equivalence may be useful: 1 W = 8.766 kWh per year.) Sources: NASA's Surface meteorology and Solar Energy (eosweb.larc.nasa.gov; www.africanenergy.com/files/File/Tools/AfricaInsolationTable.pdf; www.solarpanelsplus.com/; solar-insolation-levels/lightbucket.wordpress.com/2008/02/24/insolation-and-a-solar-panels-true-power-output/.)

Figure 2.

Electricity, gas and transport demand; and modelled wind production, assuming 33 GW of capacity, all on the same vertical scale. Wind production is modelled by scaling data from Ireland.

Figure 3.

Power consumption per person versus population density, in 2005. Point size is proportional to land area (except for areas less than 38 000 km2 (e.g. Belgium), which are shown by a fixed smallest point size to ensure visibility). The straight lines with slope -1 are contours of equal power consumption per unit area. Seventy-eight per cent of the world's population live in countries that have a power consumption per unit area greater than 0.1 W m-2. (Average powers per unit area are sometimes measured in other units, for example kWh per year per square metre; for the reader who prefers those units, the following equivalence may be useful: 1 W= 8.766 kWh per year.)

[See also David MacKay's Map of the World]

Figure 4.

Power consumption per person versus population density, in 2005. Point size is proportional to land area. Line segments show 15 years of 'progress' (from 1990 to 2005) for Australia, Libya, the USA, Sudan, Brazil, Portugal, China, India, Bangladesh, the UK and the Republic of Korea. Seventy-eight per cent of the world's population live in countries that have a power consumption per unit area greater than 0.1 W m-2.

[See also David MacKay's Map of the World]

Figure 5.

Power consumption per person versus population density, from 1600 or 1800 to 2005. OECD, Organization for Economic Cooperation and Development.

Figure 6.

Power consumption per person versus population density, in 2005. Point size is proportional to land area. The diagonal lines are contours of power consumption per unit area. The grey box corresponds to the region shown in figures 3 and 4.

[See also David MacKay's Map of the World]

Figure 7.

Electricity production from AllEarth Renewables Solar Farm, 350 Dubois Drive, South Burlington, VT (latitude 44°26' N), during the last six months of 2011 and the first six months of 2012; and insolation (10 year average) for Montpelier (33 miles away from the farm) from the NASA Surface meteorology and Solar Energy Data Set. Photo courtesy of AllEarth Renewables.

Figure 8.

Solar farms' average power per unit land area versus the local insolation (i.e. average incident solar flux per unit of horizontal land area). Filled triangles, squares, circles and pentagons show ground-based solar photovoltaic farms. The other point styles indicate roof-mounted photovoltaic farms and solar thermal facilities. Where the solar farm name is shown in black, actual electricity-production data have been displayed; otherwise, for names in grey, the electricity production is a predicted value. (See tables 1-3 for data.) Both axes show average power per unit area, averaging over the whole year including day and night. (Average powers per unit area are sometimes measured in other units, for example kWh per year per square metre; for the reader who prefers those units, the following equivalence may be useful: 1 W=8.766 kWh per year.)

Figure 9.

Solar farms' load factors versus their insolation. The grey lines show, as guides to the eye, the relationships (load factor)/(insolation/(1000 W m-2)) = {1.33, 1.0, 0.67}.

Figure 10.

Solar farms' average power per unit land area versus their load factor (i.e. the ratio of their average electrical output to their capacity). Three of the Spanish thermal solar electric power stations have load factors greater than 27% and therefore fall off this chart to the right. (See tables 1-3 for data.)

Figure 11.

Electricity demand in the UK and modelled solar production, assuming 40 GW of solar capacity. (a-c) The upper curves show Britain's electricity demand, half-hourly, in 2006. The lower data sequence in (a) is a scaled-up rendering of the electricity production of a roof-mounted south-facing 4.3 kW 25 m2 array in Cambridgeshire, UK, in 2006. Its average output, year-round, was 12 kWh per day (0.5 kW). The data have been scaled up to represent, approximately, the output of 40 GW of solar capacity in the UK. The average output, year round, is 4.6 GW. The area of panels would be about 3.8 m2 per person, assuming a population of roughly 60 million. (For comparison, the land area occupied by buildings is 48 m2 per person.) (b,c) The lower curves show, for a summer week and a winter week, the computed output of a national fleet of 40 GW of solar panels, assuming those panels are unshaded and are pitched in equal quantities in each of the following 10 orientations: south-facing roofs with pitch of (1) 0°, (2) 30°, (3) 45°, (4) 52°, and (5) 60°; (6) south-facing wall; and roofs with a pitch of 45° facing (7) southeast, (8) southwest, (9) east and (10) west. On each day, the theoretical clear-sky output of the panels is scaled by a factor of either 1, 0.547, or 0.1, to illustrate sunny, partially sunny, and overcast days. Note that, on a sunny weekend in summer, the instantaneous output near midday comes close to matching the total electricity demand. Thus, if solar photovoltaics is to contribute on average more than 11% of British electricity demand without generation being frequently constrained off, significant developments will be required in demand-side response, large-scale storage, and interconnection.

Figure 12.

Contour plot of the total cost of a photovoltaic system, in a sunny location, capable of giving a steady 1 kW output with (a) 14 h of storage (as might be appropriate in a location such as Los Angeles); (b) 120 h of storage (as might be appropriate in cloudier locations), as a function of the cost of the panels and the cost of storage. Assumptions: load factor, 20%; efficiency of electrical storage, 75%; fraction of final electricity that comes through the store, 60%. The capital costs per kW are equivalent to the following undiscounted costs per kWh, assuming 20 years' operation: Costs of battery storage are from Poonpun & Jewell. Cost of pumped storage (p.s., \$125 per kWh) is based on Auer & Keil. The cost of the Vermont solar farm (section 3), built in 2011, was \$5630 per kW of capacity (\$12 million for 2130 kW), without electricity storage. Note that the total cost of this solar farm is more than three times the cost of its photovoltaic modules (roughly \$1750 per kW).

Figure 13.

Contour plot of potential average consumption of electrical power as a function of production and energy intensity of storable materials. The points show these two properties for six materials: ice, ammonia, aluminium, hot water, hydrogen and gasoline from thin air. Where there are two points, the right-hand coordinate indicates proven achievable energy intensity of production, and the left-hand coordinate shows the conceivable energy intensity with efficiency improvements. For ice, ammonia, aluminium, hot water and hydrogen, the production shown is today's production; the arrows indicate levels to which production could rise if stored ice were used as a carrier of cold for air-conditioning, if stored water were used as a carrier of heat for space-heating, and if hydrogen took a significant role in transport. For gasoline production from air, the 'production' shown is today's per capita consumption of transport fuels in the UK.

Figure 14.

Solar farms' average power per unit land-area versus their capacity. (See tables 1-3 for data.)