Gerry's Comments

Other options are to create PV roofs over railways or roads.

Where railways have been electrified with overhead lines, the vertical supports for the power lines may be used to support the PV roof.

I have calculated that PV over railways in the UK could generate at least 1700 TWh/yr, which is more than 4 times the UK's consumption of about 383 TWh/yr. Even if it was limited to the rail routes that are electrified now, the potential is at least 560 TWh/yr.

A report last year by Bloomberg Renewable Energy Finance showed that worldwide subsidies for fossil fuels are 12 times the subsidies given to renewables.

Also, fossil fuel generators are still using the atmosphere as a free trash can for their CO2 emissions. This has to stop.

With those two problems fixed, we are probably already past the crossover.

This is great news! It would be even better if they had adopted an 'upstream' version of cap-and-trade: see http://www.mng.org.uk/turnofftap and http://www.mng.org.uk/euets .

"This leaves open the possibility that Solar FITs will be reduced if they are too successful."

Its hard to know what "too successful" could mean when climate scientists say that there should not be more than 350 ppm of CO2 in the atmosphere and we are already at 388 ppm.

With concentrating solar power (CSP), it is relatively easy and cheap to store solar heat so that the generation of electricity may continue at night and on cloudy days. See http://www.trec-uk.org.uk/csp/no_sun.htm .

A couple of corrections:

* The project is based on research by the German Aerospace Centre (DLR) and their estimates for costs up to 2050 are 350 billion Euros for CSP plants and 45 billion Euros for a 100 GW Eumena-wide supegrid of HVDC transmission lines.

* The picture shown comes from a different project which happens to include some CSP. There are much better pictures here: http://www.trec-uk.org.uk/pictures.htm .

There's a lot more information on http://www.trec-uk.org.uk/index.htm .

All of China's present or future demands for electricity could be met using concentrating solar power (CSP) in the sunny north and west of the country (see http://www.trec-uk.org.uk/csp/worldwide.html). That said, it would be prudent to develope wind power and other renerwable sources alongside CSP.

Re the cost of CSP (query by "Anonymous"), there is information about it here:http://www.trec-uk.org.uk/csp/costs.htm .

Thanks for this useful and interesting article.

Using concentrating solar power (CSP), less than 1% of the world's deserts could generate as much electricity as the world is using. It is feasible and economic to transmit solar electricity for 3000 km or more via highly-efficient HVDC transmission lines, and 90% of the world's population lives within 2700 km of a desert.

Further information about CSP and the 'DESERTEC' concept developed by the TREC international network of scientists and engineers may be found at:

http://www.desertec.org/

and

http://www.trec-uk.org.uk/

The headline is not quite accurate. A CSP plant is being built at Ordos in China and there are CSP plants in Australia.

CSP projects around the world can be seen on Google Earth via a link from http://www.trec-uk.org.uk/resources.htm#CSP_GE .

These developments are good news but we need to remember that, with concentrating solar thermal power (CSTP), it is possible to store solar energy very cheaply for hours or days in the form of heat. Further information may be found here: http://www.trec-uk.org.uk/csp/no_sun.htm .

Large scale HVDC transmission grids have many benefits. The main ones are summarised here:http://www.trec-uk.org.uk/elec_eng/grid.htm .

Al Gore's inspirational vision needs to be combined with other measures to cut CO2. Probably the cheapest and easiest way to start cutting CO2 emissions is a massive programme to renovate buildings to bring them as close as possible to the German "passivhaus" standard (see http://www.mng.org.uk/gh/renewable_energy/ecorenovation.htm).

Distributed generation is good (PV on rooftops, micr-CHP, micro-wind, solar water heaters etc) but there are still good reasons to build large-scale transmission grids (see http://www.trec-uk.org.uk/elec_eng/grid.htm) -- and that makes it possible to take advantage of large-scale but often remote sources of renewable energy such as CSP in desert regions, wave power, offshore wind power, tidal power etc.

We'll almost certainly end up with a hybrid system that combines the best of local generation with the best of remote sources of renewable energy.

"... analysts evaluated the solar resource in the Southwest [of the US] and ... found that CSP [concentrating solar power] could provide nearly 7,000 GW of capacity, or about seven times the current total US electric capacity." (Tackling Climate Change in the US, American Solar Energy Society, January 2007, page 17, emphasis added).

This is a much better way to go! For more information see http://www.trec-uk.org.uk/ .