Interview: Professor Toby Peters


Toby Peters is, among other things, a Visiting Professor at the University of Birmingham in Power and Cold Power and also at Heriot-Watt University in Transformational Innovation for Sustainability. He is the Founder of both Highview Power Storage (2004) and Dearman (2011) and he was the academic lead of the 2015 ‘Doing Cold Smarter’ Policy Commission.

First of all, we would like to thank you very much for taking the time to take part in this interview.

Q. Considering your very extensive professional and academic career in the field, why do you feel that cooling needs to be addressed now more than ever? Why is it important and why should civil society and policy-makers be concerned about the expected global increase of cooling demands?

A. Until recently cooling was the Cinderella of the energy debate – but it is a pillar of civilisation. Without cold, the supply of food, medicine and data would simply break down. But conventional technologies are also energy intensive and highly polluting, causing 10% of global CO2 emissions – three times that attributed to aviation and shipping combined. Cooling demand is also growing at a furious pace, driven by population growth, rising incomes and changing lifestyles in developing countries, and the impact of climate change.

Researchers at Lawrence Berkeley National Laboratory estimate the global stock of room air conditioners will rise 700 million by 2030 and 1.6 billion by 2050.[i]  And as a result, according to another forecaster, by the end of the century on current trends and a business as normal approach, global air conditioning will consume 10,000TWh[ii], about half the electricity consumed worldwide for all purposes in 2010. While demand will be overwhelmingly driven by growth in the developing countries, but will also continue to rise in developed economies; the European Commission forecasts energy demand for building cooling in the EU will rise 70% by 2030.[iii]

If this projected demand were met by existing carbon-intensive grid electricity it would be an environmental catastrophe.  On the other hand, supplying it through green electricity would be a monumental and expensive task: to generate 10,000TWh from wind would, for example, require 4.6TW of turbine capacity, more than ten times the world’s current total.[iv] Nor is it solely a problem of the total amount of energy required; air conditioning also contributes enormously to peak electricity demand, putting huge stress on grids from the US to India.

Cooling loads are not just electrical, however.  Air conditioning in vehicles is powered by petrol or diesel, for example, and in hot countries air conditioning can consume up to 40% of a bus’ fuel. And refrigerated trucks and trailers are typically cooled by a secondary diesel engine (‘transport refrigeration unit’ or TRU) that can emit up to six times as much nitrogen oxides (NOx) and 29 times as much particulate matter (PM) as the propulsion engine pulling it around. As with air conditioning, demand for transport refrigeration is forecast to soar.

It is clearly vital to find ways to limit the impact of cooling demand growth on emissions, grid stress and cost. This will often mean storing off-peak energy, which is cheaper and lower carbon, for use at peak times, and/or converting it to some other form of energy. The question then is the form in which this off-peak energy should be stored. If the service you need is cooling, it may be far more efficient to store energy thermally to supply that service in the form of cold rather than as chemical energy in batteries.



Q. What are the next steps for the ‘greening’ of cold? How would this impact society from a social, environmental and economic perspective? Can we address the ‘greening’ of cold with existing technologies?

A. The environmental impact of conventional cooling technologies can be partially mitigated through existing efforts to improve efficiency and regulatory changes such as the phasing out of HFC refrigerant gases. but this does nothing to tackle the 75% of cooling emissions that come from energy consumption.

Evidence also suggests the energy efficiency of cooling in some sectors could be raised by 30% on the basis of best-in-class products and practices alone, but even if business barriers could be overcome, this improvement would be utterly overwhelmed by the projected 33-fold growth in developing world air conditioning demand for example or the quadrupling of transport refrigeration vehicles. We clearly need to do cold smarter, and we believe the answer is to radically improve efficiency by developing a new ‘Cold Economy’.

The Cold Economy applies a system-level analysis to recruit vast untapped resources of waste cold, ‘free’ cold, waste heat, renewable heat, and ‘wrong time’ energy – such as wind or nuclear power produced at night when demand is low – to radically improve the efficiency of cooling, and reduce its environmental impact and cost. The Cold Economy is less about individual clean cold technologies – although these are vital – and more about the efficient integration of cooling with waste and renewable resources, and with the wider energy system.

The key insight of the Cold Economy is that energy can be used, stored and moved thermally rather than necessarily converted into electricity and then converted again to provide cooling.  The Cold Economy approach is powerful because we then start by are asking ourselves ‘what is the energy service we require, and how can we provide it in the least damaging way’, rather than ‘how much electricity do I need to generate?’



Q. You are the founder of the Highview Power Storage and Dearman. Both companies design technologies using liquid air. Could you please let us know a bit more about the role of liquid air in the Dearman engine and storage? And why is liquid air so relevant?

A. The purpose of liquid air – as with batteries or hydrogen – is to store ‘wrong time’ low or zero carbon electricity, which can then be used to displace high carbon coal or gas in electricity generation and petrol or diesel in vehicles. The difference though is that it is storing cold and power, not just power.

Clean cold technologies are already being developed to run on liquid air or nitrogen. Dearman, for example, is developing its cryogen-fuelled piston engine to provide simultaneous cold and power as a Transport Refrigeration Unit (TRU), and in a stationary engine to provide backup power and cooling for commercial buildings. Analysis for its report, Liquid Air on the European Highway, found that ten EU countries that operate 80% of the EU refrigerated vehicle fleet have estimated spare liquid nitrogen production capacity of around 9,000 tonnes per day, enough to cool some 70,000 refrigerated vehicles.

The use of liquid air or nitrogen for cooling need not be restricted to cold chains, but could also extend to commercial vehicle air conditioning – on buses, for instance. The cooling load in a hot climate is so great that providing air conditioning on a diesel powered bus could raise its fuel consumption by half, and in an electric bus severely reduces the vehicle’s range. A cooling system based on liquid air or nitrogen could solve both problems. In countries with unreliable electricity grids, liquid air or nitrogen could also provide back-up power and cooling for data centres, hospitals and other buildings with an absolute requirement for uninterrupted power and cooling.

Critically though liquid allows us to capture and recycle waste cold of LNG. The global trade in liquefied natural gas (LNG) has increased significantly in recent years, and is vital to the energy security of a growing number of countries. Yet an extraordinary amount of the energy contained in the cryogen is simply thrown away. LNG is natural gas that has been refrigerated to -162°C to make it compact enough to transport by tanker, but this cold energy or “packaging” is normally discarded during re-gasification at the import terminal. Of the 111 LNG import terminals worldwide, only 23 do any form of cold recovery. Even here the use of the waste cold is usually limited to industrial plants close to the terminal, and only at times when LNG is actually being re-gasified, which in many cases occurs only intermittently. These factors limit the amount of cold that can be recycled, but this could be raised by converting it into novel energy vectors that store and transport it for use on demand such as liquid air. Recycling waste cold in this way would produce cheap, low carbon, zero-emission cryogenic ‘fuel’ to provide distributed cold and power for vehicles and buildings.



Q. The Birmingham Policy Commission released the study ‘Doing Cold Smarter’ (available here), what feedback have you received from the potential roadmap stakeholders (i.e. energy sector, urban planners and policy makers)? Does the Birmingham Policy Commission envision other plans for the ‘greening’ of cold or further steps with this roadmap?

 A. As the world’s population heads to 9 billion by mid-century, there is no question that we will need far more cooling. We will need it to conserve food, water and other resources; tackle poverty, hunger, health and climate change; and underpin growth and development. But if the new cold chains, data centres and air conditioners are cooled with conventional technologies, we will only solve one set of problems by creating another – quite possibly an environmental catastrophe.

There is an urgent need to resolve the cooling dilemma: to provide clean cold, through novel low carbon and zero-emission technologies and new approaches such as the ‘cold economy’ to secure all the benefits of cooling whilst mitigating the downside. Of course, clean cold is no panacea, but it is an essential pre-condition for sustainable development and we need to make it an integral part of our energy roadmap.

Research into cooling has historically failed to match its economic importance and environmental impact. Across the EU as a whole, annual public Refrigeration and Air Conditioning R&D funding has averaged £23.5 million per year or 0.22% of total funding for engineering research and scarcely 0.2% in the UK.

However this shortfall has begun to be rectified, through a series of major public and investments into research into clean cold and the Cold Economy.   More and more clean cold technologies are securing grant funding and in the UK.  And for example, we recently saw the launch of the Energy Research Accelerator (ERA), a major collaboration between six Midlands universities and over fifty companies to tackle some of the biggest energy challenges. ERA secured £180 million in funding from government and industry to cover three themes, one of which is thermal energy (t-ERA) – explicitly including the development of the global Cold Economy led by teams at the University of Birmingham and Loughborough University

The CryoHub is a €7 million European grant for pan-European consortium of researchers led by London South Bank University. The three year project will research the potential efficiency gains that might be achieved by integrating Liquid Air Energy Storage with existing cooling and heating equipment found in refrigerated warehouses and food processing plants – a good example of the Cold Economy approach. It will use large scale liquid air energy storage to absorb local intermittent renewable generation and supply it back to the grid, while simultaneously providing cooling to the cold store and reducing its peak power requirements. Project partners include universities and companies from the UK, Belgium, France, Spain and Bulgaria. But there is still much to do to ensure we think thermally not just electrically and cold demand is designed into the energy system of tomorrow.



Q. As a coordinator of the coolingEU academic mirror group, which aspects of cooling do you think need to be tackled at the EU level to raise awareness on the importance of cooling?

A. I think we need to look at the global role of cooling. Cold is key to the UN’s Sustainable Development Goals. Billions of people in developing countries live without cooling and suffer the consequences daily through hunger and ill-health. As just one example, the lack of adequate ‘cold chains’ of refrigerated warehousing and transport causes two million vaccine preventable deaths each year, and the waste of 200 million tonnes of food – with consequences far beyond hunger and inflated food prices. Food wastage occupies a land area almost twice the size of Australia[v]; consumes 250km3 of water per year, three times the volume of Lake Geneva; and emits 3.3 billion tonnes of CO2, making it the third biggest emitter after the US and China.[vi]

Cold chains don’t just reduce post-harvest food loss, but also allow subsistence farmers to earn more by maintaining the quality of their produce and selling it further afield, especially when this means they can reach more distant cities and major centres of consumption. The same lettuce sold for 10 rupees at the farm gate in Haryana state in India can fetch 100 rupees or more in downtown Delhi – but only if the farmer can get it there in the same condition as one imported by air-freight from a highly developed global agri-business and cold chain. What’s more, the market connectivity afforded by of a cold chain enables and incentivises farmers to raise their output because they will earn more from what they produce; whereas its absence means that any effort to increase yield will also cause higher wastage – so dousing the incentive.

But increasing subsistence farmers’ income by expanding the use of conventional, highly polluting cold chain technologies would simply mitigate one problem by significantly worsening another.

Additional information can be found in the following links:

  • University of Birmingham document on Clean cold and the Global Goals here
  • University of Birmingham’s post on: Green, White and Blue: Why India Needs a Third Agricultural Revolution here


[i] Benefits of Leapfrogging to Superefficiency and Low Global Warming Potential Refrigerants in Room Air Conditioning, Nihar Shah et al, Lawrence Berkeley National Laboratory, October 2015,


[iii] European Commission, pers.comm.

 [iv] 10,000TWh / 8760 = 1.14TW. 1.14TW x 4 = 4.6TW. Assuming 25% average global load factor: Current global wind capacity 432GW:

[v] Land used to produce wasted food is 1.4 billion hectares, cf Food wastage footprint, Impacts on natural resources, FAO, 2013, 1.4 billion hectares = 14,000,000km2. Australia = 7,686,850km2, cf

[vi] Food wastage footprint, Impacts on natural resources, FAO, 2013,