Prospects for Anaerobic Digestion Remain Positive Despite Failure of Copenhagen Climate Summit

A recent article in the New Civil Engineer magazine, the magazine of the UK’s Institution of Civil Engineers, discusses how now after the failure of the Copenhagen Climate Summit it will be possible to rise to the challenge of complying with UK carbon reduction pledges.

You only have to read the following paragraphs from the above NCE article to realise the enormity of the task ahead even for just the water industry:

The UK government has pledged that emissions of greenhouse gases will be cut by 80% C02 equivalent - measured against 1990 levels - within the next 40 years.

Yet over the same time Britain's population is expected to grow by anywhere from 15% to 30%, per capita water use is rising and it is likely the [water] industry will be required to meet higher quality and environmental standards - all driving up energy consumption. How are companies going to square the circle?

As readers of my Anaerobic Digestion blog, I am sure that you will not want me to dwell upon the negatives, such as the fact that so far almost all we have seen so far has been rhetoric, while UK carbon emissions have continued to rise.

This is despite that fact that we have exported so much of our emissions as our manufacturing industry has declined, in favour of imports. Even the water industry admits to a 10% rise in carbon emissions since 2000.

So, where will we find the huge cuts needed? We will clearly have to go far beyond efficiency savings which might optimistically, for example, within the water industry provide 30% to 45% savings given the right (high) levels of investment needed.

Opportunities to cut carbon further do undoubtedly exist, and to quote the 14 January 2010 NCE article, for the UK Water Industry example, these might comprise:

• demand reduction
• improved design
• adoption of new technologies
• operational improvements
• better management of catchments and drainage systems and
• wider use of renewable energy.

Now those that have experience of Anaerobic Digestion will know that with present technology the potential for the AD industry to provide renewable energy is large enough to be worthwhile, but not that big. Even with a very high rate of adoption AD will not provide enough power to meet the demand as a major contributor to the 80% reduction target. To do that would need a technical revolution.

But, again quoting from the NCE article, Ofwat’s head of Climate Change Policy Mike Keil has said that:

“Looking at the next five to ten years you can say with some certainty there won't be a technical revolution. Certainly there will be innovation contributing to carbon reductions, but not a huge step change".

Beyond 2020 it is possible there will be breakthroughs as research and development bears fruit and new technologies come to maturity.

So, based on current technologies, an 80% reduction looks extremely difficult, if not verging on impossible, to achieve. The lack of hard commitments from the Copenhagen Summit contributes to a feeling that the political commitment to “pledges” far outweighs the ability to deliver, given the enormity of the task ahead.

Nevertheless, it is important that Engineers do push forward where this can be done on the basis of economically justifiable results. That is where the prospects for UK Anaerobic Digestion do look very good indeed.

Again, referring to the Water Industry; In the next investment period the UK water companies will be making the most of the opportunities offered by enhanced sewage sludge digestion technologies to generate high calorific biogas and reduce the final volume of biosolids as waste for disposal. Adding hydrolysis up front before the digester will help to greatly increase the amount of conversion of the total biomass in sludge to methane, for example.

Another development to continue will be that:

"By using biogas to drive combined heat and power engines, enhanced biodigestion offers potential to make sewage treatment works energy self-sufficient," 

says Mott MacDonald head of water regulation Andrew Heather [again quoted here from the NCE article].

Some companies, we are told, are also planning to clean-up biogas so that it can be used as a vehicle fuel or sold into the national gas grid. It will be interesting to report on that in this blog in due course.

In addition to the digestion of their own sewage works sludge some Water Companies are also, we are told, looking to increase energy from biodigestion by supplementing sewage sludge with food and industrial waste.

So, the prospects for Anaerobic Digestion are good, but the big question mark, which continues to become more urgent to answer remains.

Where will the rest of these carbon savings come from, which are so badly needed to plug the huge gap between current reality and an 80% saving?