About the author

David MacKay is a Professor in the Department of Physics at the University of Cambridge. He studied Natural Sciences at Cambridge and then obtained his PhD in Computation and Neural Systems at the California Institute of Technology. He returned to Cambridge as a Royal Society research fellow at Darwin College. He is internationally known for his research in machine learning, information theory, and communication systems, including the invention of Dasher, a software interface that enables...

UK energy history

Primary fuel kWh d p kWh(e) d p Table K1- Breakdown of pnmary ----energy sources in the UK (2004-2006). Figure K.2. Left UK net electricity supplied, by source, in kWh per day per person. (Another 0.9 kWh d p is generated and used by the generators themselves.) Right the energy gap created by UK power station closures, as projected by energy company EdF. This graph shows the predicted capacity of nuclear, coal, and oil power stations, in kilowatt-hours per day per person. The capacity is the...

Population densities

Figure J.1 shows the areas of various regions versus their populations. Diagonal lines on this diagram are lines of constant population density. Bangladesh, on the rightmost-but-one diagonal, has a population density of 1000 per square kilometre India, England, the Netherlands, and Japan have population densities one third that about 350 per km2. Many European countries have about 100 per km2. At the other extreme, Canada, Australia, and Libya have population densities of about 3 people per...

Greenhouse gas conversion factors

Portugal 525 United Kingdom 580 emissions (gCO2 per kWh of chemical energy) Figure I.10. Emissions associated with fuel combustion. Source DEFRA's Environmental Reporting Guidelines for Company Reporting on Greenhouse Gas Emissions. Figure I.9. Carbon intensity of electricity production (gCO2 per kWh of electricity). Figure I.10. Emissions associated with fuel combustion. Source DEFRA's Environmental Reporting Guidelines for Company Reporting on Greenhouse Gas Emissions. 10000 20000 30000 40000...

Stuff II

Dieter Helm and his colleagues estimated the footprint of each pound's worth of imports from country X using the average carbon intensity of country X's economy (that is, the ratio of their carbon emissions to their gross domestic product). They concluded that the embodied carbon in imports to Britain (which should arguably be added to Britain's official carbon footprint of 11 tons CO2e per year per person) is roughly 16 tons CO2e per year per person. A subsequent, more detailed study...

The raw tidal resource

The tides around Britain are genuine tidal waves. (Tsunamis, which are called tidal waves, have nothing to do with tides they are caused by underwater landslides and earthquakes.) The location of the high tide (the crest of the tidal wave) moves much faster than the tidal flow - 100 miles per hour, say, while the water itself moves at just 1 mile per hour. The energy we can extract from tides, using tidal pools or tide farms, can never be more than the energy of these tidal waves from the...

Real wave power systems

How effective are real systems at extracting power from waves Stephen Salter's duck has been well characterized a row of 16-m diameter ducks, feeding off Atlantic waves with an average power of 45 kW m, would deliver 19 kW m, including transmission to central Scotland (Mollison, 1986). The Pelamis device, created by Ocean Power Delivery, has taken over the Salter duck's mantle as the leading floating deep-water wave device. Each snake-like device is 130 m long and is made of a chain of four...

The physics of deepwater waves

Waves contain energy in two forms potential energy, and kinetic energy. The potential energy is the energy required to move all the water from the troughs to the crests. The kinetic energy is associated with the water moving around. People sometimes assume that when the crest of a wave moves across an ocean at 30 miles per hour, the water in that crest must also be moving at 30 miles per hour in the same direction. But this isn't so. It's just like a Mexican wave. When the wave rushes round the...

Improving the coefficient of performance

You might think that the coefficient of performance of a condensing boiler, 90 , sounds pretty hard to beat. But it can be significantly improved upon, by heat pumps. Whereas the condensing boiler takes chemical energy and turns 90 of it into useful heat, the heat pump takes some electrical energy and uses it to move heat from one place to another (for example, from outside a building to inside). Usually the amount of useful heat delivered is much bigger than the amount of electricity used. A...

An energyefficient office

The National Energy Foundation built themselves a low-cost low-energy building. It has solar panels for hot water, solar photovoltaic (PV) panels generating up to 6.5 kW of electricity, and is heated by a 14-kW ground-source heat pump and occasionally by a wood stove. The floor area is 400 m2 and the number of occupants is about 30. It is a single-storey building. The walls contain 300 mm of rockwool insulation. The heat pump's coefficient of performance in winter was 2.5. The energy used is 65...

Burning household waste

SELCHP (South East London Combined Heat and Power) www.selchp. com is a 35 MW power station that is paid to burn 420 kt per year of black-bag waste from the London area. They burn the waste as a whole, without sorting. After burning, ferrous metals are removed for recycling, hazardous wastes are filtered out and sent to a special landfill site, and the remaining ash is sent for reprocessing into recycled material for road building or construction use. The calorific value of the waste is 2.5kWh...

Jatropha also has low power per unit area

Jatropha is an oil-bearing crop that grows best in dry tropical regions (3001000 mm rain per year). It likes temperatures 20-28 C. The projected yield in hot countries on good land is 1600 litres of biodiesel per hectare per year. That's a power per unit area of 0.18 W m2. On wasteland, the yield is 583 litres per hectare per year. That's 0.065 W m2. If people decided to use 10 of Africa to generate 0.065W m2, and shared this power between six billion people, what would we all get 0.8 kWh d p....

Solar II

On p42 we listed four solar biomass options 1. Coal substitution. 2. Petroleum substitution. 3. Food for humans or other animals. 4. Incineration of agricultural by-products. We'll estimate the maximum plausible contribution of each of these processes in turn. In practice, many of these methods require so much energy to be put in along the way that they are scarcely net contributors (figure 6.14). But in what follows, I'll ignore such embodied-energy costs. If we grow in Britain energy crops...

Notes and further reading

Drag coefficient for 747 from www.aerospaceweb.org. Other 747 data from 2af5gw . Albatross facts from 32judd . - Real jet engines have an efficiency of about e 1 3. Typical engine efficiencies are in the range 23 -36 adg. For typical aircraft, overall engine efficiency ranges between 20 and 40 , with the best bypass engines delivering 30-37 when cruising htm . You can't simply pick the most efficient engine however, since it may be heavier (I mean, it may have bigger mass per...

Ekranoplans

The ekranoplan, or water-skimming wingship, is a ground-effect aircraft an aircraft that flies very close to the surface of the water, obtaining its lift not from hurling air down like a plane, nor from hurling water down like a hydrofoil or speed boat, but by sitting on a cushion of compressed air sandwiched between its wings and the nearby surface. You can demonstrate the ground effect by flicking a piece of card across a flat table. Maintaining this air-cushion requires very little energy,...

Many boats are birds too

Some time after writing this cartoon of flight, I realized that it applies to more than just the birds of the air - it applies to hydrofoils, and to other high-speed watercraft too - all those that ride higher in the water when moving. Figure C.13 shows the principle of the hydrofoil. The weight of the craft is supported by a tilted underwater wing, which may be quite tiny compared with the craft. The wing generates lift by throwing fluid down, just like the plane of figure C.2. If we assume...

Ecofriendly aeroplanes

Occasionally you may hear about people making eco-friendly aeroplanes. Earlier in this chapter, however, our cartoon made the assertion that the transport cost of any plane is about According to the cartoon, the only ways in which a plane could significantly improve on this figure are to reduce air resistance (perhaps by some new-fangled vacuum-cleaners-in-the-wings trick) or to change the geometry of the plane (making it look more like a glider, with immensely wide wings compared to the...

The physics of wind power

To estimate the energy in wind, let's imagine holding up a hoop with area A, facing the wind whose speed is v. Consider the mass of air that passes through that hoop in one second. Here's a picture of that mass of air just before it passes through the hoop And here's a picture of the same mass of air one second later The mass of this piece of air is the product of its density p, its area A, and its length, which is v times t, where t is one second. The kinetic energy of this piece of air is 1 2...

Electric cars is range a problem

People often say that the range of electric cars is not big enough. Electric car advocates say no problem, we can just put in more batteries - and that's true, but we need to work out what effect the extra batteries have on the energy consumption. The answer depends sensitively on what energy density we assume the batteries deliver for an energy density of 40 Wh kg (typical of lead-acid batteries), we'll see that it's hard to push the range beyond 200 or 300 km but for an energy density of...

List of web links

This section lists the full links corresponding to each of the tiny URLs mentioned in the text. Each item starts with the page number on which the tiny URL was mentioned. See also http tinyurl.com yh8xse (or www. for a clickable page with all URLs in this book. If you find a URL doesn't work any more, you may be able to find the page on the Wayback Machine internet archive f754 . 8 ydoobr www.bbc. co .uk radi o4 news anyquest ions_.tr ans cripts_20060127. shtml 9 25e59w news .bbc .co.uk 1 low...

Solar

We are estimating how our consumption stacks up against conceivable sustainable production. In the last three chapters we found car-driving and plane-flying to be bigger than the plausible on-shore wind-power potential of the United Kingdom. Could solar power put production back in the lead The power of raw sunshine at midday on a cloudless day is 1000 W per square metre. That's 1000 W per m2 of area oriented towards the sun, not per m2 of land area. To get the power per m2 of land area in...

Electric vehicles

The REVA electric car was launched in June 2001 in Bangalore and is exported to the UK as the G-Wiz. The G-Wiz's electric motor has a peak power of 13 kW, and can produce a sustained power of 4.8 kW. The motor provides regenerative braking. It is powered by eight 6-volt lead acid batteries, which when fully charged give a range of up to 77 km. A full charge consumes 9.7 kWh of electricity. These figures imply a transport cost of 13 kWh per 100 km. Manufacturers always quote the best possible...

Lights on the traffic

In some countries, drivers must switch their lights on whenever their car is moving. How does the extra power required by that policy compare with the power already being used to trundle the car around Let's say the car has four incandescent lights totalling 100 W. The electricity for those bulbs is supplied by a 25 -efficient engine powering a 55 -efficient generator, so the power required is 730 W. For comparison, a typical car going at an average speed of 50km h and consuming one litre per...

Kettles and cookers

Britain, being a civilized country, has a 230 volt domestic electricity supply. With this supply, we can use an electric kettle to boil several litres of water in a couple of minutes. Such kettles have a power of 3 kW. Why 3 kW Because this is the biggest power that a 230 volt outlet can deliver without the current exceeding the maximum permitted, 13 amps. In countries where the voltage is 110 volts, it takes twice as long to make a pot of tea. If a household has the kettle on for 20 minutes...

Solar photovoltaic

Photovoltaic (PV) panels convert sunlight into electricity. Typical solar panels have an efficiency of about 10 expensive ones perform at 20 . (Fundamental physical laws limit the efficiency of photovoltaic systems to at best 60 with perfect concentrating mirrors or lenses, and 45 without concentration. A mass-produced device with efficiency greater than 30 would be quite remarkable.) The average power delivered by south-facing 20 -efficient photovoltaic panels in Britain would be Figure 6.5...

Producing lots of electricity plan L

Some people say we don't want nuclear power How can we satisfy them Perhaps it should be the job of this anti-nuclear bunch to persuade the NIMBY bunch that they do want renewable energy in our back yard after all. We can create a nuclear-free plan by taking plan D, keeping all those renewables in our back yard, and doing a straight swap of nuclear for Tide 1 kWh d Hydro 0.2 kWh d Waste 1.1 kWh d Tide 3.7 Wave 2 Hydro 0.2 Waste 1.1 desert power. As in plan N, the delivery of desert power...

Producing lots of electricity plan N

Plan N is the NIMBY plan, for people who don't like industrializing the British countryside with renewable energy facilities, and who don't want new nuclear power stations either. Let's reveal the plan in stages. First, we turn down all the renewable knobs from their very high settings in plan D to wind 2kWh d p (5GW average) solar PV 0 wave 0 tide 1 kWh d p. We've just lost ourselves 14kWh d p (35GW nationally) by turning down the renewables. (Don't misunderstand Wind is still eight-fold...

Producing lots of electricity the components

To make lots of electricity, each plan uses some amount of onshore and offshore wind some solar photovoltaics possibly some solar power bought from countries with deserts waste incineration (including refuse and agricultural waste) hydroelectricity (the same amount as we get today) perhaps wave power tidal barrages, tidal lagoons, and tidal stream power perhaps nuclear power and perhaps some clean fossil fuel, that is, coal burnt in power stations that do carbon capture and storage. Each plan...

Common features of all five plans

In my future cartoon country, the energy consumption is reduced by using more efficient technology for transport and heating. In the five plans for the future, transport is largely electrified. Electric engines are more efficient than petrol engines, so the energy required for transport is reduced. Public transport (also largely electrified) is better integrated, better personalized, and better patronized. I've assumed that electrification makes transport about four times more efficient, and...

Green ambitions meet social reality

Yes, technically, Britain has huge renewables. But realistically, I don't think Britain can live on its own renewables - at least not the way we currently live. I am partly driven to this conclusion by the chorus of opposition that greets any major renewable energy proposal. People love renewable energy, unless it is bigger than a figleaf. If the British are good at one thing, it's saying no. Wind farms No, they're ugly noisy things. Solar panels on roofs No, they...

Variation of wind speed with height

Taller windmills see higher wind speeds. The way that wind speed increases with height is complicated and depends on the roughness of the surrounding terrain and on the time of day. As a ballpark figure, doubling the height typically increases wind-speed by 10 and thus increases the power of the wind by 30 . Some standard formulae for speed v as a function of height z are 1. According to the wind shear formula from NREL ydt7uk , the speed varies as a power of the height where v10 is the speed...

Power density of tidal stream farms

Imagine sticking underwater windmills on the sea-bed. The flow of water will turn the windmills. Because the density of water is roughly 1000 times that of air, the power of water flow is 1000 times greater than the power of wind at the same speed. What power could tidal stream farms extract It depends crucially on whether or not we can add up the power contributions of tidefarms on adjacent pieces of sea-floor. For wind, this additivity assumption is believed to work fine as long as the wind...

Solar biomass

All of a sudden, you know, we may be in the energy business by being able to grow grass on the ranch And have it harvested and converted into energy. That's what's close to happening. All available bioenergy solutions involve first growing green stuff, and then doing something with the green stuff. How big could the energy collected by the green stuff possibly be There are four main routes to get energy from solar-powered biological systems 1. We can grow specially-chosen plants and burn them...

How much do renewables fluctuate

However much we love renewables, we must not kid ourselves about the fact that wind does fluctuate. Critics of wind power say Wind power is intermittent and unpredictable, so it can make no contribution to security of supply if we create lots of wind power, we'll have to maintain lots of fossil-fuel power plant to replace the wind when it drops. Headlines such as Loss of wind causes Texas power grid emergency reinforce this view. Supporters of wind energy play down this problem Don't worry -...

Funny units

Is this a way to make solar panels sound good Once all the 7 000 photovoltaic panels are in place, it is expected that the solar panels will create 180000 units of renewable electricity each year - enough energy to make nine million cups of tea. This announcement thus equates 1 kWh to 50 cups of tea. As a unit of volume, 1 US cup (half a US pint) is officially 0.241 but a cup of tea or coffee is usually about 0.181. To raise 50 cups of water, at 0.181 per cup, from 15 C to 100 C requires 1 kWh....

Some questions about electric vehicles

You've shown that electric cars are more energy-efficient than fossil cars. But are they better if our objective is to reduce CO2 emissions, and the electricity is still generated by fossil power-stations This is quite an easy calculation to do. Assume the electric vehicle's energy cost is 20 kWh(e) per 100 km. (I think 15 kWh(e) per 100 km is perfectly possible, but let's play sceptical in this calculation.) If grid electricity has a carbon footprint of 500 g per kWh(e) then the effective...

Queries

Aren't turboprop aircraft far more energy-efficient No. The comfortably greener Bombardier Q400 NextGen, the most technologically advanced turboprop in the world, according to its manu- Figure 5.1. Taking one intercontinental trip per year uses about 30 kWh per day. Figure 5.1. Taking one intercontinental trip per year uses about 30 kWh per day. Figure 5.2. Bombardier Q400 NextGen. www.q400.com. Figure 5.2. Bombardier Q400 NextGen. www.q400.com. facturers www.q400.com , uses 3.81 litres per 100...

Bibliography

Methane generation from UK landfill sites and its use as an energy resource. Energy Conversion and Management, 37(6 8) 1111-1116. doi doi 10.1016 0196-8904(95)00306-1. 00000006 art00306. Amos, W. A. (2004). Updated cost analysis of photobiological hydrogen production from Chlamydomonas reinhardtii green algae -milestone completion report. www.nrel.gov docs fy04osti 35593. pdf. Anderson, K., Bows, A., Mander, S., Shackley, S., Agnolucci, P., and Ekins, P. (2006)....

Wind

The UK has the best wind resources in Europe. Wind farms will devastate the countryside pointlessly. How much wind power could we plausibly generate We can make an estimate of the potential of on-shore land-based wind in the United Kingdom by multiplying the average power per unit land-area of a wind farm by the area per person in the UK power per person wind power per unit area x area per person. Chapter B p263 explains how to estimate the power per unit area of a wind farm in the UK. If the...

Queries On Solar Power Generated Stirling Engine

I'm confused In Chapter 6, you said that the best photovoltaic panels deliver 20 W m2 on average, in a place with British sunniness. Presumably in the desert the same panels would deliver 40 W m2. So how come the concentrating solar power stations deliver only 15-20 W m2 Surely concentrating power should be even better than plain flat panels Good question. The short answer is no. Concentrating solar power does not achieve a better power per unit land area than flat panels. The concentrating...

The bottom line

The non-solar numbers add up as follows. Wind 24kWh d p hydro 3.6kWh d p tide 0.3kWh d p wave 0.5kWh d p geothermal 8kWh d p - a total of 36kWh d p. Our target was a post-European consumption of 80kWh d per person. We have a clear conclusion the non-solar renewables may be huge, but they are not huge enough. To Table 30.4. World sunniness figures. 3doaeg Table 30.4. World sunniness figures. 3doaeg complete a plan that adds up, we must rely on one or more forms of solar power. Or use nuclear...

Every BIG helps

We've established that the UK's present lifestyle can't be sustained on the UK's own renewables except with the industrialization of country-sized areas of land and sea . So, what are our options, if we wish to get off fossil fuels and live sustainably We can balance the energy budget either by reducing demand, or by increasing supply, or, of course, by doing both. Have no illusions. To achieve our goal of getting off fossil fuels, these reductions in demand and increases in supply must be big....

Can we store GWh

We are interested in making much bigger storage systems, storing a total of 1200 GWh about 130 times what Dinorwig stores . And we'd like the capacity to be about 20 GW - about ten times bigger than Dinorwig's. So here is the pumped storage solution we have to imagine creating roughly 12 new sites, each storing 100 GWh - roughly ten times the energy stored in Dinorwig. The pumping and generating hardware at each site would be the same as Dinorwig's. Assuming the generators have an efficiency of...

For the impatient reader

Are you eager to know the end of the story right away Here is a quick summary, a sneak preview of Part II. First, we electrify transport. Electrification both gets transport off fossil fuels, and makes transport more energy-efficient. Of course, electrification increases our demand for green electricity. Second, to supplement solar-thermal heating, we electrify most heating of air and water in buildings using heat pumps, which are four times more efficient than ordinary electrical heaters. This...

The climatechange motivation

The climate-change motivation is argued in three steps one human fossil-fuel burning causes carbon dioxide concentrations to rise two carbon dioxide is a greenhouse gas three increasing the greenhouse effect increases average global temperatures and has many other effects . Figure 1.4. Carbon dioxide CO2 concentrations in parts per million for the last 1100 years, measured from air trapped in ice cores up to 1977 and directly in Hawaii from 1958 onwards . I think something new may have happened...

Solar thermal

The simplest solar power technology is a panel making hot water. Let's imagine we cover all south-facing roofs with solar thermal panels - that would be about 10 m2 of panels per person - and let's assume these are 50 -efficient at turning the sunlight's 110 W m2 into hot water figure 6.3 . Multiplying 50 x 10 m2 x 110 W m2 we find solar heating could deliver I colour this production box white in figure 6.4 to indicate that it describes production of low-grade energy - hot water is not as...

Heating and the ground

Here's an interesting calculation to do. Imagine having solar heating panels on your roof, and, whenever the water in the panels gets above 500C, pumping the water through a large rock under your house. When a dreary grey cold month comes along, you could then use the heat in the rock to warm your house. Roughly how big a 500C rock would you need to hold enough energy to heat a house for a whole month Let's assume we're after 24kWh per day for 30 days and that the house is at 160C. The heat...

Living on other countries renewables

Whether the Mediterranean becomes an area of cooperation or confrontation in the 21st century will be of strategic importance to our common security. Joschka Fischer, German Foreign Minister, February 2004 We've found that it's hard to get off fossil fuels by living on our own re-newables. Nuclear has its problems too. So what else can we do Well, how about living on someone else's renewables Not that we have any entitlement to someone else's renewables, of course, but perhaps they might be...

The cost of sucking

Regions Food Shortages

Today, pumping carbon out of the ground is big bucks. In the future, perhaps pumping carbon into the ground is going to be big bucks. Assuming that inadequate action is taken now to halt global carbon pollution, perhaps a coalition of the willing will in a few decades pay to create a giant vacuum cleaner, and clean up everyone's mess. Before we go into details of how to capture carbon from thin air, let's discuss the unavoidable energy cost of carbon capture. Whatever technologies we use, they...

Cost of switching from fossil fuels to renewables

Every wind farm costs a few million pounds to build and delivers a few megawatts. As a very rough ballpark figure in 2008, installing one watt of capacity costs one pound one kilowatt costs 1000 pounds a megawatt of wind costs a million a gigawatt of nuclear costs a billion or perhaps two. Other renewables are more expensive. We the UK currently consume a total power of roughly 300 GW, most of which is fossil fuel. So we can anticipate that a major switching from fossil fuel to renewables and...

Sustainable fossil fuels

Kingsnorth Power Station

It is an inescapable reality that fossil fuels will continue to be an important part of the energy mix for decades to come. UK government spokesperson, April 2008 Our present happy progressive condition is a thing of limited duration. We explored in the last three chapters the main technologies and lifestyle changes for reducing power consumption. We found that we could halve the power consumption of transport and de-fossilize it by switching to electric vehicles. We found that we could shrink...

Producing lots of electricity plan G

Some people say we don't want nuclear power, and we don't want coal It sounds a desirable goal, but we need a plan to deliver it. I call this plan G, because I guess the Green Party don't want nuclear or coal, though I think not all Greens would like the rest of the plan. Greenpeace, I know, love wind, so plan G is dedicated to them too, because it has lots of wind. I make plan G by starting again from plan D, nudging up the wave contribution by 1 kWh d p by pumping money into wave research and...

What about algae

Algae are just plants, so everything I've said so far applies to algae. Slimy underwater plants are no more efficient at photosynthesis than their terrestrial cousins. But there is one trick that I haven't discussed, which is standard practice in the algae-to-biodiesel community they grow their algae in water heavily enriched with carbon dioxide, which might be collected from power stations or other industrial facilities. It takes much less effort for plants to photosynthesize if the carbon...

Some comparisons and costs

So, how's our race between consumption and production coming along Adding both shallow and deep offshore wind to the production stack, the green stack has a lead. Something I'd like you to notice about this race, though, is this contrast how easy it is to toss a bigger log on the consumption fire, and how difficult it is to grow the production stack. As I write this paragraph, I'm feeling a little cold, so I step over to my thermostat and turn it up. It's so simple for me to consume an extra 30...

Contemporary offices

New office buildings are often hyped up as being amazingly environment-friendly. Let's look at some numbers. The William Gates building at Cambridge University holds computer science researchers, administrators, and a small cafe. Its area is 11110 m2, and its energy consumption is 2392MWh y. That's a power per unit area of 215 kWh m2 y, or 25 W m2. This building won a RIBA award in 2001 for its predicted energy consumption. The architects have incorporated many environmentally friendly features...

Energy loss and temperature demand degreedays

Since energy is power x time, you can write the energy lost by conduction through an area in a short duration as energy loss area x U x AT x duration , and the energy lost by ventilation as Both these energy losses have the form Maximum England and Wales Sweden W m2 K 1985 1991 2002 1975 2001 Figure E.3. U-values required by British and Swedish building regulations. where the Something is measured in watts per C. As day turns to night, and seasons pass, the temperature difference AT changes we...

What about rolling resistance

Rolling Resistance Velocity

Some things we've completely ignored so far are the energy consumed in the tyres and bearings of the car, the energy that goes into the noise of wheels against asphalt, the energy that goes into grinding rubber off the tyres, and the energy that vehicles put into shaking the ground. Collectively, these forms of energy consumption are called rolling resistance. The standard model of rolling resistance asserts that the force of rolling resistance is simply proportional to the weight of the...

Index

747, 132 1698, 6, 19 1769,6 1910, 7 1979, 20 2050, 203 A380, 132 AA battery, 89 absolution, 3 academics, 293 accelerator-driven system, 166 action, 203 addiction, 203 Adelman, Kenneth, 40 advertisement, 72, 154 advertising standards authority, 126 advocating acts of consumption, 4 aerodynamic efficiency, 273 agricultural waste, 206 air energy consumption, 92 hot, 51 air changes, 289, 296 air resistance, 118 air travel neutralization, 211 air-conditioning, 52, 144, 151 in vehicles, 131...

Other peoples estimates of wind farm power per unit area

Ampair 600

In the government's study the UK onshore wind resource is estimated using an assumed wind farm power per unit area of at most 9 W m2 capacity, not average production . If the capacity factor is 33 then the average power production would be 3 W m2. The London Array is an offshore wind farm planned for the outer Thames Estuary. With its 1GW capacity, it is expected to become the world's largest offshore wind farm. The completed wind farm will consist of 271 wind turbines in 245 km2 6o86ec and...

The Desertec plan

An organization called DESERTEC www.desertec.org is promoting a plan to use concentrating solar power in sunny Mediterranean countries, and high-voltage direct-current HVDC transmission lines figure 25.7 to deliver the power to cloudier northern parts. HVDC technology has been in use since 1954 to transmit power both through overhead lines and through These beautiful concentrators deliver 14 W m2. Photo courtesy of Stirling These beautiful concentrators deliver 14 W m2. Photo courtesy of...

Streetlights and traffic lights

Do we need to include public lighting too, to get an accurate estimate, or do home and work dominate the lighting budget Street-lights in fact use about 0.1 kWh per day per person, and traffic lights only 0.005 kWh d per person - both negligible, compared with our home and workplace lighting. What about other forms of public lighting - illuminated signs and bollards, for example There are fewer of them than street-lights and street-lights already came in well under our radar, so we don't need...