Climate change – again: Are we in trouble, or not?

Two scientific studies produced recently show just how difficult it is for us to work it out.

First, a bit of background.

Any process that removes carbon from the atmosphere can act as a carbon sink. These include basic processes like having the gas dissolve into the ocean, to more complex ones, such as the sequestration that appears to take place in mature forests. Taken together though, the impact is huge.

We think that carbon sinks remove about 60 per cent of the CO2 that us humans pump into the atmosphere each year. What’s left is referred to as the airborne fraction.

Now – researchers from the University of Bristol’s QUEST programme on climate change and earth system modelling say in one breath that over the last 50 years the average fraction of global CO2 emissions that remained in the atmosphere each year has increased from 40 to 45 per cent.

This suggests a decrease in the efficiency of the natural sinks – such as the oceans and terrestrial ecosystems.

However, a second team found no increase in the airborne fraction over the same period and that the trend was in fact -0.2 ± 1.7 per cent per decade – which is essentially zero – concluding that the capacity of terrestrial ecosystems and the oceans to absorb CO2 has not diminished.

Says science commentator Anthony Watts:

“This work is extremely important for climate change policy, because emission targets to be negotiated at next month’s United Nations Climate Change Conference in Copenhagen have been based on projections that have a carbon free sink already factored in. Some researchers have cautioned against this approach, pointing at evidence that suggests the sink has already started to decrease.”

But, who’s right? Says Ars Technica‘s John Timmer:

“These are two highly technical papers that use different data sets and different methods; it’s no surprise that they’ve reached different conclusions, and it will probably take the scientific community a few months of digesting them and comparing them to previously published work in order to reach a consensus on which one (if either) is likely to better reflect reality. Using them to generate competing coverage in the popular press doesn’t do a public that understands climate science poorly any favors.”

Watch out for new energy saving technologies

Most domestic heating and automotive air conditioning requires a lot of energy. Domestic space heating and hot water account for 25 per cent of energy consumption in the UK. Across the EU, vehicle air conditioning uses about five per cent of the vehicle fuel consumed annually. Within the UK it is responsible for over two million tonnes of CO2 emissions.

Stick with me!

Researchers have long been aware of a much more energy efficient way to drive heat pumps (or air conditioners) using adsorption technology. This uses heat from a gas flame or engine waste heat to power a closed system containing only active carbon and refrigerant.

When the carbon is at room temperature it adsorbs the refrigerant and when heated the refrigerant is driven out. A process which alternately heats and cools the carbon can be used to extract heat from the outside air and put it into radiators or hot water tanks. With air conditioning it extracts the heat from the inside of the car.

The major snag has been that adsorption technology to date would need to be roughly 300 litres in volume for a car air conditioner and larger for a heat pump to heat your house.  Clearly that is not going to fit into a car and the volume of unit required for domestic heating probably couldn’t fit under your stairs at home either…

Now – I’ve got to the point – researchers at the University of Warwick have made a breakthrough in adsorption systems design that

UoW's lead researcher Bob Critoph

dramatically shrinks these devices, making them small and light enough for use in both domestic heating and automotive air conditioning.

They have devised and filed a patent on a clever new arrangement that distributes thin (typically 0.7mm thick) sheets of metal throughout the active carbon in the heat exchanger. Each of these sheets contains more than a hundred tiny water channels (typically 0.3mm in diameter) designed to make the heat transfer much more efficient.

This has enabled the Warwick team to create adsorption based equipment that is up to 20 times smaller than was previously possible.

The researchers expect that their new adsorption technology can create domestic heat pumps that will produce a 30 per cent or more reduction in domestic fuel bills (and CO2 emissions) compared to even the best condensing boiler. In car air conditioning systems their new system can exploit waste heat from the engine, converting it into useful cooling.

Because no (or very little) mechanical power is then taken from the engine it will reduce both fuel consumption and CO2 emissions by nearly five per cent. The research team also anticipates that in new vehicle models the system can be integrated with little or no extra cost.

We’re told the UoW’s engineers have had significant interest in the new technology from a range of companies, and they have already entered into a technical partnership with a major global vehicle manufacturer to develop and demonstrate the technology.  There has also been considerable interest from the domestic heating and hot water market.

This significant commercial interest has led to a new spin-off company, Sorption Energy Limited, being set up by Warwick Ventures, the University’s technology transfer office, and H2O Venture Partners. Initially the company will use the new patent pending technology to focus on two high value markets: greener heating and hot water systems for houses and air conditioning for cars.

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