Monday, August 28, 2023

"Growing out of Our Troubled Civilization." Film Screening + post-film Q&A. 6 pm, Tuesday, October 24th 2023, Reading Biscuit Factory (Reading, UK).

You can either just turn up on the night and buy a ticket there, or book tickets in advance

This is a film screening (+ post-film Q&A), arranged with Transition Town Reading, to be held at the independent cinema, "Reading Biscuit Factory," at 6 pm on October 24th (2023), 1 Queens Walk, Reading RG1 7QE.

Here is the booking link (or just turn up on the door).     


With a theme of "Growing out of Our Troubled Civilization", join Transition Town Reading for three films, offering a realistic but practical perspective on where we now are, and where we might go. This is part of Reading International Festival, and includes a post-film Q&A.

"The Sequel" (1 hour) shines a light on the work and legacy of David Fleming, a historian, economist, and ecologist with a deep understanding of how we got into our current predicament, and a compelling vision of how we can recover what we have lost as the market economy has worked its way into every aspect of our lives.

"Together We Grow" is a 40-minute documentary that tells the inspiring story of a thriving hub helping to build resilience into its local community by growing, sewing, repairing, sharing – you name it, Common Unity is doing it!

"Earth Action Challenge" is a short (4-minute) film about a local eco-action event held at Reading's own Lavender Place Community Garden.

Panelists for post-film Q&A:

Professor Chris Rhodes, Director of Fresh-lands Environmental Actions, and Chair of Transition Town Reading.

Tracey Rawling Church, Co-chair of the Reading Climate Change Partnership.

Natalie Ganpatsingh, Director of Nature Nurture.

Evening Programme:

The ordering of events is: 6.00 pm, "The Sequel"; 7.00 pm, short break; 7.10, "Together We Grow"; 7.50, "Earth in Action Challenge"; 8.00 pm, Q&A panel. Finish about 8.25 pm. 

Thursday, August 10, 2023

The Energy and Climate Conundrum.

I'm giving a Plenary Lecture at a conference next week, entitled: "The Energy and Climate Conundrum." A key focus is on energy demand reduction, in parallel with low-carbon energy generation.

And this is the Abstract for the talk:

The Energy and Climate Conundrum.

Christopher J. Rhodes*

Fresh-lands Environmental Actions, Reading, UK.

*Corresponding Author email:


The global supply of oil is the lifeblood of current industrial civilization. 84% of the primary energy used by humans on Earth is from oil, coal and natural gas, whose combustion is causing global heating, which drives climate change. Hence, low carbon energy sources must be implemented rapidly and on a massive scale. However, this will necessitate the enhanced recovery of particular materials, including lithium, cobalt, graphite, rare earth elements and indeed copper, for a largely electrified energy system. Thus, it may be useful to choose/devise technologies that utilise Earth Abundant elements1, and e.g. to substitute aluminium for copper to build this on the necessary scale.

However, decarbonising our energy sources, alone, will not solve the problem, because the human species is in ecological overshoot. Thus, reduction in our demand for energy, and for all resources is essential. Since it is the system of civilization that must be fixed, any means to accomplish this must also be systemic in nature, and bring about a consolidated amelioration of climate change, biodiversity loss, and relentless degradation of the ecosphere. A time-limited framework for this is set out in a recent “Scientists’ Warning” paper2, which underlines six principal focus areas: Energy, Atmospheric Pollutants, Nature, Food Systems, Population Stabilisation, and Economic Reforms.

Keywords: Energy; Overshoot; Scientists’ Warnings;

(1) Rhodes, C.J. Endangered elements, critical raw materials and conflict minerals. Science Progress, 2019, Vol. 102(4) 304-350.

(2) Barnard P. et al. World scientists’ warnings into action, local to global. Science Progress 2021, Vol. 104(4) 1–32. 


Prof. Chris Rhodes is Director of the consultancy, Fresh-lands Environmental Actions, and a Board member of Scientists Warning Europe. He became a full professor in physical chemistry in his early 30s, and has published over 250 peer reviewed academic papers and an extensive online collection of essays and journalism. He has advised on low-carbon energy for the European Commission. Chris has given invited lectures at many international conferences and universities around the world, and at numerous popular science venues, e.g. Cafe Scientifique, along with radio and televised interviews. His novel “University Shambles,” a black comedy based on a disintegration of the U.K. university system, was nominated for a Brit Writers Award. Chris holds Fellowships of the Royal Society of Chemistry, the Linnean Society of London, and the Royal Society of Arts. He is Chair of Transition Town Reading (U.K.). He has also published a collection of poetry and a series of children’s picture books.

Friday, August 04, 2023

Passive Daytime Radiative Cooling.

The most effective form of renewable, low-carbon energy is energy not used at all. Passive daytime radiative cooling (PDRC) is a method proposed to ameliorate global heating, by enhancing the radiation of heat to outer space using thermally-emissive surfaces placed around the Earth. There is no energy consumed in running this technology, and hence no associated greenhouse gas emissions. Since all natural materials absorb more heat during the day than at night, PDRC surfaces are designed with a high solar reflectance (to minimize heat gain) and strong thermal (heat) radiation transfer through the atmosphere's infrared window (in the region, 8–13 ┬Ám), so that temperatures are reduced during the daytime. PDRC offers the advantage over solar radiation management that it increases the emission of radiative heat, rather than merely reflecting solar radiation back into space before it is absorbed by the environment and heat thus generated from it.

It has been estimated that if PDRC were installed over 1–2% of the Earth's surface area, a brake would be applied to relentless global heating, and temperature increases reined in to survivable levels. The cooling potentials are greater for desert and temperate regions than for tropical climates, since both humidity and cloud cover inhibit the efficiency of the devices. Cheap materials have been developed for PDRC that can be mass produced, including coatings, thin films, aerogels, and metafabrics, to reduce the need for air conditioning, attenuate the urban heat island effect, and cool human bodies in conditions of extreme temperature.

Scientists at MIT have invented a PDRC device that can cool things down by more than 13 degrees Celsius, and significantly below the ambient air temperature, in full sunlight on a cloudless day. The critical component for this device is a polyethylene foam insulating material called an aerogel. The foam is extremely lightweight (just 1/50th of the density of water), looks and feels somewhat like a marshmallow, and both blocks and reflects the visible rays of sunlight, thus preventing them from passing through it. It is also transparent to the infrared radiation wavelengths that transport heat, so they can escape and be radiated out and away.

Hot objects cool down as a result of radiative heat loss, emitting midrange infrared radiation. Since air is effectively transparent to these wavelengths, the heat energy is lost into space.

The basic concept was demonstrated a year ago, using a narrow strip of metal, as a physical barrier to shade the device from direct sunlight, and prevent it from heating up. However, its cooling power was less than one half that the new system, with its highly efficient insulating layer, without which the heat from the surrounding air raises the temperature of the device.

The use of air conditioners and electric fans already accounts for about 20% of the total electricity consumed in buildings around the world, which amounts to around 10% of current total global electricity consumption. It is expected that demand for air conditioning will increase from the current 1.6 billion to 5.6 billion AC units by 2050, becoming one of the top drivers of global electricity demand, despite negative consequences in terms of increased energy use, costs, and global warming, described as a "vicious cycle.”

This situation may nonetheless be mitigated, since PDRCs are most often applied to building envelopes, which can significantly lower the temperatures within. When a  reflective white roof was combined with a PDRC, a doubling of the energy saved for cooling could be obtained. Elsewhere, it is quoted that PDRC coatings directly covering a roof reflect a large proportion of solar radiation and achieve a lower roof temperature, which can reduce cooling loads by 18%93%. By covering 10% of a building's roof with a multilayer PDRC surface, some 35% of air conditioning used during the hottest hours of the day can be avoided. Hence, PDRCs can act to replace, or reduce the energy demand of, air conditioning, and also help to ease the pressure on energy grids during periods of peak demand.

It has been reported that, in suburban residential areas in the United States, PDRCs can result in a 26%–46% reduction in energy use and an average lowering of temperatures by 5.1 °C.

With the addition of "cold storage to utilize the excess cooling energy of water generated during off-peak hours, the cooling effects for indoor air during the peak-cooling-load times can be significantly enhanced" and air temperatures may be reduced by 6.6–12.7 °C

As global temperatures increase, such PDRC cooling devices may find widespread applications, with the advantage that they use no energy, incur no greenhouse gas emissions, and hence do not add to the burden of global heating, unlike conventional refrigeration and air conditioning systems which need electricity to run them.

Integrated, hybrid systems, that combine thermal insulation, evaporative cooling and radiative cooling, can also be used to perhaps double the time that fruit and vegetables can be kept fresh, and in remote regions where refrigeration is not viable due a lack of a reliable electricity supply.

However, there are a number of challenges attendant to a wide scale commercialisation of PDRC, that must be considered: for example, the cost and availability of the materials employed to fabricate particular devices, along with their durability (lifetime) and performance under prevailing environmental conditions, which will vary appreciably according to location.