One only has to look at the UK Domestic energy consumption chart to see how difficult is a 60% reduction in CO2 emmissions. Every energy flow has to be 60% replaced by a zero carbon alternative. Even when all alternatives are considered together it seems like an impossible task. No-one wants nuclear power - but it is clear that it must be included.

Energy saving (see Carbon Trust) will be an equally important element. Why are we still using filament light bulbs? The fact that we are says we are not serious about tackling Climate Change. switching to low energy bulbs could have an impact 10 times the wind power installed so far - and at considerably lower cost!

The analysis here shows that we need all the technologies we are aware of today, plus huge energy saving and this is still probably not enough.


The good news is that wind is a renewable energy source.

Why it is being supported so strongly is not clear. Wind power has a number of serious shortcomings:

So in summary wind is an expensive renewable source that when implemented 10 times what we have now will make a 2% CO2 reduction, or around 3% points of the 60% CO2 reduction we need by 2050.

Taking the broader renewable picture we need to implement wind power 10 times more than present, and then implement 30 more technologies to an extent 10 times current wind power and we will be there! This gives a picture of the task ahead.

CO2 Sequestration

CO2 Sequestration may play a small role. This is not as easy as may first seem. The problem is that most of the CO2 we emit is at a low pressure and emitted from many dispersed places. It is totally uneconomic to recover CO2 from our car exhausts and home gas heating systems. The chart below taken from a presentation by Timothy R. Carr of Kansas University shows the problem:

The major current source of concentrated CO2 at pressure is fertiliser production (Haber process). This generates 39 million tonnes carbon (x44/12 for CO2) out of a total of nearly 7000. i.e around 0.5%. However production, typically at 2000te/d from a single location, is still probably too small for a CO2 sequestration project.

The next most attractive source will be power generation - but existing plants are not viable as the CO2 generated is at low concentration and pressure. New technology - Integrated Gasification Combined Cycle (IGCC) is proven - so called 'clean coal technology', and can use gas as feedstock. This enables CO2 extraction using the same technology as proven for decades in fertilser manufacture. The only obstacle is the cost, and the government policy that will make the cost acceptable.

So CO2 Seqestration will require implementation of new capital, probably IGCC electricity generation, and the government policy that enables the economics to become viable.


The principle gain from microgeneration is the use of the heat generated from power generation to provide space heating and hot water. Current power generation converts only one third of the fuel into electricity and the discards two thirds of the energy as low grade waste heat in massive cooling towers. Conversly in our homes we take a high value fuel (typically gas) and use it to very efficiently (c90%) generate low grade heat as space heating and hot water. With microgeneration we generate electricity in our homes and use the waste heat - with the net effect of generating electricity at 90% efficiency instead of 30%. Microgeneration is an example of Combined Heat and Power (CHP)

For more details see the DTI Microgeneration Strategy. Stirling engines - e.g. the EON 'Wispergen' generated around 15% electricity from gas with the balance as heat. With the more efficient homes we will need in the future fuel cells may become the prefered option delivering a 50:50 mix of power and heat.

There are still many questions to be answered on microgeneration. For best utilisation they need to be connected to the grid. This presents grid stability issues to be addressed.

Microgeneration has the potential to make large CO2 reductions through utilisation of the combined heat. This programme needs accelerating to see if the projected benefits can be realised.

Biofuels (biodiesel)

Conversion of vegetable oil to biodiesel by transesterification is an efficient, low temperature, relatively low capital cost technology. Conversion is around 1te biodiesel from 1te vegetable oil. There is still the question of what energy might be derived from the straw and crushed seeds (meal). The European Union has a target that 5,75% of transport fuel should be bio based by 2010. A calculation on rape seed yeilds and European fuel use suggests that a plantation 500km by 500km will be required to produce the oil required. This is roughly the size of the non-mountainous parts of France:

Biodiesel is excellent from a CO2 perspective. However it seems unlikely that we will be able to spare enough land to produce the vegetable oil for anthing like the 60% reduction we need by 2050.


This has been strongly supported and criticised in the USA. The main concern is the energy required to distil the ethanol to get it to the concentration required. Early reports suggested that plants were using as much energy in fossil fuel to run the process as the energy in the ethanol product. More recent studies, and process improvements now claim around 25% more energy in the bio-ethanol than the fossil energy required to produce it. Brazil also makes bio-ethanol and claims better efficiency by using energy from the crop waste to power the plant.

Bio-oil/Pyrolysis oil

Fast Pyrolysis is a process of rapidly heating biomass to 500C to produce an oil and residual char. The oil has a calorific value about half that on fuel oil and can be burned or gasified to generate electricity or used as a raw material for making chemicals. For much more information on this visit Biomass Pyrolysis Network. This process could be used to process biomass waste, energy crops, trees etc to heat, electricity or chemicals. It is not economical without support - but probably would be with equivalent support to that given to wind power - and pyrolysis oil can be used when you want ti use it - not just when the wind blows!

Biomass Gasification

Gasification converts biomass into a symthesis gas that can be burned to produce power or turned into chemicals. Pyrolysis oil can also be gasified and, being liquid is easier to feed into a gasifier. Pyrolysis oil could be co-fed into a IGCC (integrated gasification combined cycle) power plant. The syngas produced can also be made into chemicals. CHOREN, with shell are proving technology to convert biomass into synthetic diesel, taking advantage of the support available for bio-fuels

Anaerobic Digestion

Anaerobic digestion has the advantage of being able to convert wet biomass into energy. Pyrolysis and gasification prefer biomass with less than 15% moisture. Greenfinch claim around 1MWhr/dry te of biomass feed. Anaerobic digestion produces a low calorific gas, similar to 'landfill gas' that can be burned in a gas engine to produce electricity. (Landfill gas is currently the UKs major source of renewable electricity - but will decline as we recycle more of our biomass waste). Current anerobic digestion requires long digestion times and hence large vessels and high capital cost. Newer, fast anaerobic digestion processes will be much more attractive.

Biomass Potential

The European Environment Agency projects the potential for Biomass (energy crops and waste) to contribute up to 15-15% of energy of the EU25 countries in 2030. See How much bioenergy can Europe produce without harming the environment?. This shows encouraging potential. Policy must support this to turn 'potential' into 'reality'. It requires 30% of land in the major EU countries to be devoted to 'environmentally-oriented farming' and 'Ambitious waste minimisation strategies'.

Fuel Cells

This is a huge area, strongly supported, that is likely, longer term, to have some impact in specific areas. See Fuel Cell Today for up-to-date news and a detailed analysis of the fuels cell technologies and markets.

Automobile fuel cells get a great deal of publicity. The benefits here is mainly from 'zero emmisions at point of use' - i.e. a local air quality benefit - and NOT a climate benefit. These are often confused. A recent life cycle anaylsis, part of the US DOE Hydrogen Program shows no 'well to wheels' benefit over hybrid electric diesel:


However fuel cells are also being developed to increase the efficiency of gas turbine power generation systems, notably by Rolls Royce.

Fuel cells also have the potential to deliver a more favorable balance of power to heat in microgeneration systems and feature strongly in the DTI Microgeneration Strategy.

Hydrogen Economy

This is much misused and abused concept. For clarity:

So if you have some nice renewable electricity that you can effectively transport via the grid - why might you want to convert it to hydrogen for which we need infrastructure? More work needs to be done here.

An Optimistic Scenario?

In an effort to move from policy to practicality we tried to paint an optimistic view of 2030. Let assume that:

CO2 reduction each of the above: This might not look too bad - until one reviews the trends and IEA data that says that we will be consuming 50% more energy in 2030. So our optimistic scenario would barely address half the CO2 surplus that is driving climate change and we will be half a degree warmer, with 440ppm CO2 in our atmosphere, very close to the 450ppm we do not want to exceed.
IEA plot showing 50% increase energy use by 2030

So we have a very serious problem, that collectively we are not tackling with the urgency required.

If we do not address climate change then our planet will sort us out for it - the hard way!

Missing links   Contact Details   Dr Mike Roberts