So, recently I have, on two occasions ended up discussing the pro’s and con’s of different power generation systems. I thought it might be helpful to capture some of the arguments here and have a place where follow-ups could be noted. Some of the balance of the argument depends on geography, some on natural resources and sustainability over the long-term. I might have made some mistakes, so I would appreciate any input.

Fossil Fuels

Fossil fuel thus not long-term sustainable, they are created from ancient organic materials which have been compressed and baked until they turn into a combustable solid, liquid or gas. It takes millions of years to produce these materials and they cannot be replaced in the lifetime of our civilisation. Continous supply of energy as long as it is needed and possible to reduce output to match demand.

1) Natural Gas Fired

Western European countries Gas fields are increasingly depleated. Cleaner burning than many other fossil fuels and relatively efficient conversion to electricity. Scales from domestic generator to power-station with good efficiency.

2) Coal Fired

Mining coal is either a difficult and dangerous operation under ground, or it can be strip mined which leaves significant scaring on the landscape. Burning coal is relatively dirty.

3) Oil Fired

Difficult and dangerous extraction as shown by the Gulf of Mexico. Quite dirty generation.

Atomic / Nuclear

Typically continous supply which is quite reliable to meet demand, but may also be wasteful if the energy is not needed off-peak.

1) Uranium Fast Breeder Reactor

Principles designed over 50 years ago for a different age, sponsored by government because the by-product is weapons grade radioactive isotopes. Easy to generate large ammounts of electricity. Expensive plant design, long-term safety implications and difficult end-of-life management for the facility. Financially difficult to justify because of the end-of-life implications but with subsidies possibly one of the most powerful continous supply generators.

2) Thorium Molten Salt Reactor

Thorium is much more efficient to extract than Uranium and relatively safe to handle. When embedded in molten halide salts then it can easily be deactivated in the case of difficulties. The isotopes it produces have a fairly safe half-life and are not very radioactive. Also because the radioactive material is contained in a liquid it cannot suffer from physical stressing like a solid fuel.

Environmental Power

1) Wind turbines

Subject to mechanical stresses, so requires difficult maintenance. However can be constructed from sustainable materials and can be recycled. Heavy bases need to be constructed with concrete but can be reused. Not dependable and predictable, cannot be adjusted to meet a growth in demand. Subject to the availability of heavy winds, with no wind there is no power generated and has to be shut down in excessive wind. Possible environmental impact to wildlife, particularly birds, and some visual/noise impact. Good energy transfer from the mechanical wind to electricity.

2) Photovoltaic

Produced from a silicon chemical substrate, environmental impact in production and risk of pollution. Poor efficiency compared to carbon impact of manufacturing and transport. Power output is subject to the availability of good levels of sun.

3) Solar-thermal-electric

By focusing the sun on a boiler or Sterling generator a clean and sustainable electricity is generated. Subject to sun availability and still difficult to transfer but with potentially less polution in manufacturing than alternatives.

4) Geo-thermal

Using the heat of the earth to produce steam and generate electricity. Dependable source of energy, subject to regional effectiveness where pockets of hot earth are available for use.

5) Tidal/wave energy

Use of the power of the sea to turn generators. This is a very powerful and clean form of energy, in areas like the British Isles a fairly consistent output can be given. Probable environmental impacts on fishing and wildlife. There is enough sea energy on the west coast of Ireland to power the entire British Isles demands for energy.

6) Hydroelectric

Requires a massive geo-engineering effort involving large ammounts of concrete which has a highly polluting production. However once constructed it can have a long lifespan of clean production.

Bio Fuels

Biofuels are sources which can be burnt to release their energy which was usually gathered through the growing of plant materials. The carbon released is almost as much as that which was consumed in the growth. However this is at the sacrifice of land which can be used for growing food, with world food shortages it is a shame to be burning crops for energy.

My brother just wrote an interesting post about hybrid cars saying how the current measures for economy we see aren’t really effective.

He has a good point, but also what worries me about hybrid vehicles is the environmental impact of them over their life-cycle. Most hybrid vehicles have batteries, these batteries are often made with toxic chemicals and heavy metals. How long do the batteries last? What happens with them when they are expired? I know my laptop battery, after two years of heavy use, is now at half its’ capabilities so how long will the very expensive batteries in a hybrid vehicle last?

Apparently if the KERS (Kinetic Energy Recovery Systems) used in F1 was applied to London Underground they would use 50% less electricity, but like in hybrid cars where would this charge get stored? Certainly not with conventional batteries because they can’t absorb charge quickly enough and have trouble with the discharge power for fast acceleration; that said Altairnano and Hitachi both claim dramatic improvements in this area. Super capacitors suffer leakage so this wouldn’t be very efficient for a standing vehicle. One of the most effective stores of energy is actually mechanical storage because conversion losses can be reduced substantially and this would be the best solution for London Underground. Fit a large spinning mass under the train and store the energy recovered in breaking deceleration directly on the mass, then couple the mass to the drive train during acceleration to give it that extra boost.

However, we can’t all carry round a huge mass in our cars because it will have a worse affect on the efficiency of a car compared to the constant stop-start of the Underground train.

Some new technology is needed and I don’t know where it will come from but, like mechanical storage, I think we will be surprised and it will come from the past!

DVB-T2 is an 'improved' version of the existing methods we use to broadcast digital television using traditional terrestrial antennas. The idea is to achieve a better than 30% improvement in available capacity.

There is a question that has been circulated to the group discussing the design of this system: "how much will it cost?", the true cost is not the transmission system but the cost of the boxes. Here are some of my thoughts, many of which I have not sent to the DVB-T2 group because they fall outside of the debate I want to involve myself in.

Continue reading “DVB-T2 the cost debate”