11 February 2016 – Lecture Room 5

Renewables – for 4M15

David MacKay FRS
Department of Engineering
University of Cambridge

Former Chief Scientific Advisor
Department of Energy and Climate Change
United Kingdom Government


Summary, and links to some slides

(1200 MW * 0.475) / (407 (km2)) = 1.4 W/m2

wind speeds in m/s

Average power consumption of suburbia

Heat & electricity 60 kWh/d / 44 m2 = 54 W/m2  60 kWh/d / 420 m2 = 5.7 W/m2
Electricity only 13 kWh/d / 44 m2 = 12 W/m2  13 kWh/d / 420 m2 = 1.2 W/m2
building-onlybuilding, garden, and road
The End
Electricity, gas, and transport demand; and fictional wind (assuming 33 GW of capacity), all on the same vertical scale.

Seasonal heat stores

Especially for old buildings




Max Fordham

Net heat collected into storage every year: 12 MWh

Seasonal heat store for community heating

heat store: 37m deep, 35m wide

roughly 1 GWh(th) - roughly 100 kWh/d per dwelling, for 50 dwellings, for 100 days

Similar size and function to ice house!

International energy trade

In the 1890s Norway exported 340,000 tons of ice each year. London Canal Museum
photo by Evan Amos roughly 0.1 kWh per banana How the current system copes with variability: heat: boiler and pipes are sized for peak demand (35 kW) 700 pounds; electricity: power stations and wires are sized for peak demand.

Energy storage

Dinorwig - 10 GWh energy; 2 GW maximum power

Storing energy in salt caverns

Natural gas: 200 GWh in a 600,000 m3 cavern. So ballpark national winter heat demand (40 kWh/d * 100 d) could be stored in about 1200 salt caverns.

this presentation was written in HTML using: Christian Steinruecken's 'slides.css' and 'slides.js'

manuals, examples, keyboard shortcuts

To verify the latest version is running, you can type "version" into a slide presentation once it has loaded; an overlay-window will pop-up, the version number of slides.js should be 1.128.

How to print:

Choose the browser's "print" function, and save a PDF.
In some browsers, one may have to explicitly select "print background colours" and "print background pictures" for the result to look acceptable. Also, one might want to de-select "print headers / page numbers".
The layout that's produced currently depends on the view mode the presentation is in.
The "grid view" will produce a PDF of slide thumbnails – the slide numbers and shortcut keywords are printed onto each slide. This sort of print-out may be useful as a paper index to bring along to a talk.
The "fullscreen view" will produce a PDF where each page is a slide. For this to work well, it helps to choose a suitable page size in the browser's print dialog; e.g. A4 landscape, and a reasonable base font size.
The "continuous view" will produce a PDF that has slides of variable height printed underneath each other. It also typesets a proper bibliography, if the corresponding tags were used in the HTML source.
Firefox may produce better layouts than Google Chrome for printing, or the other way around.

Other functions that you may or may not know:

Double-clicking a slide toggles between two view modes (e.g. full screen and grid view). This functionality may help to quickly, visually select a different slide.
There's currently an experimental fourth view mode in the mix, called "2-up". It's not well tested.
Typing "index" in Google Chrome opens a pop-up window with a list of all slides, that can reside on a different screen. Clicking a slide title in the index window opens it in the main presentation window.
Typing "help" opens a basic overlay-window of keyboard shortcuts (in the browser's locale).
Typing "timer" shows or hides a basic count-up timer in the corner; clicking it starts, stops it, double-clicking resets it.
Typing "edit" activates a built-in slide editor – perhaps useful for correcting last minute typos or adding an acknowledgment. ESC exits the editor (and all LaTeX on the slide is re-TeXed). The modified slide resides in browser memory and is not synced back to the original HTML file.
Typing "copy", "cut", "paste", "remove" can be used to crudely move or copy slides around during a presentation.
Typing "source" shows the HTML source of the current slide.
Typing "latex" exports experimental LaTeX source for the current slide.
Typing "rejax" retypesets all MathJax latex (might be useful in rare situations, e.g. after extreme changes of font size, or last minute edits).
(There's also a separate file named fancyslides.css that contains some newer slide layouts based on professional design guidelines, I might include some of these in slides.css in the future.)