BBC article on microgeneration

Interesting article from the BBC last year-
http://news.bbc.co.uk/1/hi/magazine/4785488.stm

talks about one supplier for turbines but still expensive (2k GBP plus installation) - http://www.eclectic-energy.co.uk/

and also a blogger with installed solar panels - http://community.livejournal.com/green_power_gen/

CIGS

Miasole investment - Oct 2006 - http://news.zdnet.com/2100-9584_22-6130312.html

CIGS less efficient than Silicon based cells, but much cheaper to manufacture- can be sprayed on rather than manufactured like silicon chips. Difficulty in manufacturing on large scale.


Also DayStar Technologies,
NanoSolar
HelioVolt

International Solar Electric Technology - r&d and product development - patented technique for fabrication

Stirling Engine - how it works

It really is very elegant and apparently very efficient

http://en.wikipedia.org/wiki/Stirling_engine

http://en.wikipedia.org/wiki/Image:Beta_Stirling.gif

Southern California Edison announced in August 2005 a plan to produce 500 MW from Solar powered Stirling Engines (purchased from Stirling Energy Systems) - press release

nice summary of solar in the UK

http://www.envocare.co.uk/solar_energy.htm

talks about the need for storage to deal with the variability in supply (seasons, throughout the day etc.)
mentions IEE Review, 'Let the Sun Shine In', February 2006 for recent developments
also mentions Stirling Engines:

the Stirling Engine operates with two (or more) cylinders with pistons connected to a crankshaft. One of the cylinders is heated on the outside and the other cooled. The volumes within the cylinders are interconnected and it is a sealed system; the working gas is made to move backwards and forwards between the hot and cold sections. The clever mechanism of the Stirling cycle produces rotary motion and at the same time moves heat from one location to another. The original device was invented in the early 19th century as a safe alternative to steam engines (which apparently were liable to explode) and since (like steam engines) the heat is applied externally it is often referred to as an external combustion engine. Modern versions are more complex and advanced than the simple example described here.

a few notes on solar prices

A residential solar energy system typically costs about $8-10 per Watt. Where government incentive programs exist, together with lower prices secured through volume purchases, installed costs as low as $3-4 watt - or some 10-12 cents per kilowatt hour can be achieved. Without incentive programs, solar energy costs (in an average sunny climate) range between 22-40 cents/kWh for very large PV systems.

from
http://www.solarbuzz.com/FastFactsIndustry.htm

Flisom - CIGS

www.telegraph.co.uk/money/main.jhtml?xml=/money/2007/02/19/ccview19.xml

Anil Sethi (Flison CEO) reckons his CIGS (CuInGaSe2) based solar panels will get to 80c a watt in 5 years- commercially available late 2009

white paper on solar and wave power in the US

http://ocsenergy.anl.gov/documents/docs/OCS_EIS_WhitePaper_Solar.pdf

Focused on the relevance for off-shore, but still has quite nice simple summary of different solar methods available. Thermal (Trough, Power Tower and Dish/Engine) vs PV
Hadn't really thought about the thermal side- quite elegant and relatively simple. Not clear from the paper which is more efficient


http://ocsenergy.anl.gov/documents/docs/OCS_EIS_WhitePaper_Wave.pdf

Khosla Investments

Khosla is certainly putting his money where his mouth is- list of current investments in clean energy (from http://vcratings.thedealblogs.com/2007/03/vinod_khoslas_complete_portfol.php)

1) Cellulosic - Mascoma, Celunol, Range Fuels, 1 stealth startup

2) Future Fuels - LS9, Gevo, Amyris Biotechnologies, Coskata Energy

3) Efficiency - Transonic Combustion, GroupIV Semiconductor, 1 stealth startup

4) Homes - Living Homes, Global Homes

5) Natural Gas - Great Point Energy

6) Solar - Stion, Ausra

7) Tools - Nanostellar, Codon Devices, Praj

8) Water - 2 stealth startup

9) Plastic - Segetis, 1 stealth startup

10) Corn/Sugar Fuels - Altra, Cilion, Hawaii Bio

BioFuels - another economist article

since I was just reading this, another interesting economist article- this time about biofuels
www.economist.com/printedition/displaystory.cfm?story_id=E1_RSGGDGT

seems like a fair amount of controversy around the energy balance- some even doubt it corn based ethanol is net positive. Seems clear that sugar cane (Brazil) is good (IEA puts its energy balance at 8.3).

On the positive side, it would be pretty simple to implement on a pretty wide scale, in terms of powering vehicles- can basically use the same infrastructure and the same engines. Popularity in Brazil is case in point.

Issue is competition for land- no point in destroying rain forest to make fuel for cars. Also competition for raw materials- for corn/maize based fuels, could drive up the price of foodstuffs.

Future appears to be in 'Cellulosic Ethanol' (much investment and chat from Vinod Khosla)- trees, grasses and other biomass. Very high energy balance but harder to breakdown. Development work on enzymes to break down raw stuffs more efficiently and in special new types of produce grown specifically for the purpose (fast growing, high yield, easy to break down)

Solar - economist technology quarterly

Thought this was quite useful- www.economist.com/printedition/displaystory.cfm?story_id=E1_RSGGDQV

"At present, solar power is at least two to three times as expensive as the typical electricity generated in America for retail customers."

but

"Decades of research have improved the efficiency of silicon-based solar cells from 6% to an average of 15% today, whereas improvements in manufacturing have reduced the price of modules from about $200 per watt in the 1950s to $2.70 in 2004"

"Cleantech Venture Network, an umbrella organisation based in Ann Arbor, Michigan, says VCs invested $2.9 billion in North American clean-technology start-ups in 2006"

Nice simple summary of the basics:

"The photoelectric effect was not discovered until 1839, when Alexandre Becquerel, a French physicist, observed that light could generate an electric current between two metal electrodes immersed in a conductive liquid. About 40 years later Charles Fritts, an American inventor, built the first solar cell. Made with selenium and a thin layer of gold, the device was less than 1% efficient. At the birthplace of the transistor, the now legendary Bell Laboratories, a team of scientists invented the first practical solar cell in 1954. The core of the invention was a semiconductor device"

"It is composed of two layers of semiconductor material, typically silicon, that are sandwiched together between metal contacts. One layer, of n-type material, contains lots of negatively charged free electrons; the other, of p-type material, contains an abundance of positively charged “holes”, which are spaces that can accept electrons. At the junction where the two layers meet, electrons pair up with holes, establishing an electric field that prevents electrons from moving from the n-type material to the p-type. When light of an appropriate wavelength strikes the solar cell, the individual packets of energy, called photons, knock some paired-up electrons free from their holes. The electric field then coaxes these free electrons and holes to move in opposite directions. The result is a build-up of free electrons in the n-type material, and a build-up of holes (that is, a shortage of electrons) in the p-type material. An external circuit provides a path for the electrons to return to the p-type material, producing an electric current along the way that continues as long as light strikes the solar cell."


annual reduction in manufacturing costs of about 5%; average crystalline silicon cell 13% efficient approx $3 per watt

silicon based solar cells still 90% of market - leading to silicon shortage and increase raw materials costs

"thin film" solar cells use little or no silicon (1% of 'regular cell') - high volume production difficult
e.g Amorphous Silicon cells (easier to produce) - example United Solar Ovonic
e.g. cadmium-telluride (less efficient - 9% - but cheaper to produce) example First Solar: $1.40 per watt; but additional space needed because less efficient
e.g. CIGS (copper indium gallium diselenide) very efficient (19.5%) but hard to produce
example - Nanosolar "nanoparticle ink"; Miasole- flexible encapsulants

Another alternative- lens/mirrors to focus sunlight onto cells (quoted efficiencies of 40%)- SolFocus

What's this all about

Ok-
So I want to learn more about renewable energy sources- what's the theory, how that translates into reality - and I wanted a place to save my notes and links to articles. So here it is.
No idea the best way of organizing at the moment- I guess I'll figure that out as it happens...