Sustainable Energy Without the Hot Air

Sustainable Energy Without the Hot Air
by David MacKay

Read the book for free here.

Main Points:

• Society has an addiction to fossil fuels, as the developed world gets 80-90% of our energy from fossil fuels. Why is this not sustainable? Three reasons. Easily accessible fossil fuels is a finite resource, consuming them creates massive carbon dioxide emissions, and our security is determined by our dependence on others for fossil fuels. 
• Understanding sustainable energy in terms of comprehensible and comparable quantities is rather simple: 1 kWh is one lightbulb for 24 hours. We consume 3kWh/day of food. Our bath is 5 kWh. A liter of petroleum is 10 kWh. If you drive 100 km you use 80 kWh. If you fl then you may use 10,000 kWh. 
• How fast we use energy? We use 80kWh/day by running a standard North American house. 
• The average European spends 125 kWh/day
• The average American spends 250 kWh/day
• 1 kWh/day ~ 40 Watts
• Switching off a phone charger for an entire day is the same as driving a car for one second.
• David MacKay measures power per area in W/m^2
• Graph population density vs. energy consumption per person (if you multiply these factors you get the power density) shows that the world average has crossed 0.1 W/m^2. 

• Energy Crops= 0.5 W/m^2
• Wind Power = 2.5 W/m^2 (twice power density that UK is consuming)
• Tide Pools = 2.7 W/m^2 (the North Sea is able to do this for Britain)
• Solar Panels = 20 W/m^2
• Concentrated Solar Power = 20 W/m^2
• UK sun before conversion= 110 W/m^2
• Desert sun before conversion= 250 W/m^2
• Nuclear = 1000 W/m^2 (Sizewell B is a 1 Gigawatt station)
• Compromise on wind power is that to supply the 17 kWh/day of electricity consumption, then 700 people in a community only need one 2-MW turbine.
• "To Make a Difference, renewable facilities have to be country-sized"- David MacKay
• Demand Side : Reduce population, Change Lifestyle (vegetarian), Technology/ efficiency
• Supply Side: 'Clean Coal', Nuclear Power, use other countries' renewable
• Energy use is broken down into transport, heating, and electricity
• How to make transport more efficient? (1) Small frontal area per person, (2) small weight per person reduces rolling resistance and braking losses, (3) convert energy efficiently- currently petrol/diesel engines are only 25% efficient, (4) go slowly to reduce air resistance and braking losses (5) move steadily -reduce braking losses. Cars are 80kWh per 100 person-km. Bicycle is 1 kWh per 100 person-km. A train is 6 kWh per 100 person-km which is more than ten times as good as a fossil fuel vehicle. An electric car is about 21 kWh per 100 person-km (which is about 85-90% efficient) vs. plug in hybrids that are at about 25 kWh per 100 person-km. Electric scooters are about 3 kWh per 100 person-km. 
• How to make heating more efficient? Heat loss= Leakiness*Average temperature difference. Methods to improve are (1) we can reduce the temperature difference (thermostat), (2) reduce the leakiness (25% improvement) by increasing insulation via retrofits, (3) heat delivery system could be better by using heat pumps. Japanese heat pumps that are back to front refrigerators can deliver 4.9 units of heat for every 1 unit of electrical energy (high-grade energy) that it takes.  Pumpu is a air source heat pump (moves heat from garden into kitchen). Tankman is a hot water container. 
• How to make electricity more efficient? Read your meters- you try to beat your high score. Move away from thermostats. Jevons' paradox- we can make technology more efficient, but the outcome of the efficiency measures is that we end up using more energy. 
• Storage and smart demand-management
• Gas demand varies annually and electricity demand varies daily. 
• Energy storage solutions
• Pumped Storage
• Seasonal heat storage- Canada hot water concentrating troughs that pump hot water deep into the ground. Very similar to the international energy trade- Norway used to transport 340,000 tons of ice per year to London. 
• How to make a plan that adds up: roughly triple our demand in electricity by...
• Electrifying all transport
• Insulating all buildings
• Electrifying all building-heating
• Meet this rising electricity demand by using renewable, nuclear, clean coal, and other people's renewables. If one billion people in Europe and North Africa wanted energy made by solar power, they would need to fill an area the size of Germany with solar panels. To power the United States, you would need to fill an area the size slightly smaller than Texas.
• David MacKay leaves out the energy cost of making renewables because over the lifetime of these sources it is very small (5%). PV's are very energy intensive however.
• Vegetarian vs. carnivore, which is better? The energy consumption is about 3 kWh/day and you could get this directly from plants. If you eat animals instead, those animals will need to eat quite a bit of plants. They are not 100% efficient in conversion, so you end up with a footprint that is a lot bigger (15 kWh/day that is going into the animals + fertilizers, tractors, etc.). 
• What exactly is climate science? It isn't about looking at temperature rise and CO2 ppm rise, and correlating the two. It is about how much warming you get everywhere and cooling you get elsewhere - stratospheric cooling (higher levels) and tropospheric warming (ground level).  The more sophisticated models take into account solar, volcanoes, greenhouse gases, ozone changes, and sulphate aerosols. 
• Recommendation: the public should engage in a numerate solution for climate change.

Watch Dr. David MacKay's Lecture at Harvard University's Center for the Environment!

Listen to Sir David MacKay's lecture in the House of Lords on 'Why Good Energy Policy is Difficult'

Listen to Sir David MacKay's Ted Talk titled "People, Power, Area"