Solar thermal
After decades of lead’s health effects being swept under the carpet and investigating scientists smeared, the danger of leaded petrol was finally recognised by governments in the 1970s. But it still took until well into the 1990s for bans to finally come into force. The emissions from leaded petrol are now regarded as one of the biggest public health and environmental disasters in recent history. In a similar way, the push for decarbonisation and the scramble to divest from Russian gas is dominated by high tech solutions, from nuclear fusion and fuel cells to batteries and green hydrogen, attracting enormous investment pots. Yet all these solutions have one thing in common – they are all focused on electricity, which only accounts for around 20% of our total energy consumption. Without a doubt electricity is becoming an increasingly significant energy medium but, like with engine knock, are we missing a cheaper, simpler and far more environmentally friendly solution to our energy needs? Solar thermal – using the sun’s energy to directly heat water.
Unlike with solar photovoltaics (PV), where 15–20% of solar irradiation is converted to electricity via the photoelectric effect, solar thermal collectors pass water through comparatively simple collectors, made of only plastic and annealed or blown glass. These panels can be up to 80% efficient in utilising incident sunlight. Dutch company Resolar estimates that, while a solar PV system can generate 155 kwh/m2 annually, a flat plate solar thermal collector can provide 495 kWh/m2 and a vacuum tube system 610 kWh/m2, nearly four times the energy from PV.
In 2020, 501 GW of low temperature solar thermal capacity was in operation around the world. This compares with 743 GW of wind, 708 GW of solar PV capacity and 398 GW of nuclear. This makes solar thermal one of the largest low carbon energy technologies in the world, and far and away the largest renewable heat source.
Interseasonal heat storage
Low temperature thermal storage, like solar heat collectors, are a low tech, low resource and environmentally benign technology that can quickly and easily be installed to unlock local energy sources that would otherwise be lost. The systems in Denmark are basically holes in the ground, lined with plastic and filled with water, or boreholes drilled into the ground. Unfortunately, the cost is yet to reflect this simplicity, in large part due to the little that has been invested in it.
Extending solar thermal
Another issue facing ‘solar farms’ can be the opposition to their presence on landscapes often perceived as natural; yet they can actually have significant benefits for biodiversity compared with intensive farming. Factors such as an absence of regular ploughing, reseeding and fertiliser or pesticide application can allow wildlife to flourish undisturbed, whilst the shading effect can potentially be likened to that of a woodland. A significant improvement in solar thermal installations in recent years has been achieved with steel profiles that are hammered into the ground, removing the need to significantly flatten the land or use concrete, improving the environmental benefits further, at the same time reducing costs and enabling systems to be installed in previously challenging locations. And it is not just flat plate collectors that can tap into heat. ICAX has been installing tarmac heat recovery for nearly two decades. Tarmac is one of the best thermal absorbers, so good that roads regularly deform in summer, requiring expensive and resource intensive repair. Taking the heat away could prevent this, also reducing urban heat islands in cities. The same system can be used to supply heat in winter, negating the need for gritting and reducing damage from ice freeze thaw. Right now Tackling heat demand is crucial to reducing energy costs, CO2 and pollutant emissions, and improving energy security. There is an abundance of heat sources in our towns and cities. These low-tech systems might not be as exciting as hydrogen fuel cells or nuclear fusion, but maybe instead of throwing billions of investment at the hope of being able to replicate the sun in 50 years’ time, we should look under our noses at a home grown, safe, cheap and low-resource technology that is ready to be rolled out right now.
HYDROPOWER
We have known how to store energy in hydropower reservoirs for more than a century. Hydropower is the grandaddy of renewable energy technologies. Once built, projects can deliver power and a multitude of additional benefits to communities for many generations. Hydropower’s role in the energy system is evolving as the world looks towards a zero emissions future. Wind and solar are both vital parts of the solution, but we know the limitations of nature. There will always be times when the wind doesn’t blow, and the sun doesn’t shine.
The good news is that nature also provides us with a complementary solution. Hydropower provides the means to store wind and solar energy in water and is the only established technology that can provide back-up at the tremendous scale needed to stabilise our future energy systems in a net zero world.
One of the most important areas of innovation is the integration of hydropower with other renewable technologies in so-called ‘hybrid’ projects.
We need an urgent rethink in the way we build energy markets in the context of a world facing up to climate change. Today’s markets have been designed to reward power production alone; this leaves hydropower operators uncompensated for the many additional benefits that projects bring to society that will be crucial in adjusting to a warmer world, such as irrigation, water supply, and flood and drought protection.
Most importantly, the Declaration calls for decision-makers to apply the Hydropower Sustainability Standard to align with international good practice. We urgently need to move beyond the myth that hydropower cannot be developed in a sustainable way. The Standard, launched in September 2021, is governed by a multi-stakeholder council including NGOs, civil society, governments, multilateral banks and industry. It is the f irst certification system of its kind in the renewables sector and enables progressive hydropower developers to demonstrate that their projects
Most importantly, the Declaration calls for decision-makers to apply the Hydropower Sustainability Standard to align with international good practice. We urgently need to move beyond the myth that hydropower cannot be developed in a sustainable way. The Standard, launched in September 2021, is governed by a multi-stakeholder council including NGOs, civil society, governments, multilateral banks and industry. It is the f irst certification system of its kind in the renewables sector and enables progressive hydropower developers to demonstrate that their projects are delivered sustainably.
Hydropower’s provision of grid flexibility and water management services will be essential in mitigating the effects of climate change in the future.
We simply cannot keep building variable renewables without thinking about the storage we need to support the system when the wind doesn’t blow, and the sun doesn’t shine. Hydropower is the perfect complement to wind and solar, and we have the tools and the knowledge we need to deliver it. Now is the time to act if we are to make a dent in our net zero ambitions.
What is fusion?
Fusion is a natural process that powers the sun and other stars. When light nuclei fuse to form a heavier nucleus, they release bursts of energy. This is the opposite of nuclear fission, the reaction used in nuclear power stations today, in which energy is released when a nucleus splits apart to form smaller nuclei.
To produce energy from fusion here on Earth, a combination of hydrogen gas isotopes found in seawater – deuterium and tritium – have to be heated to extreme temperatures (over 100mn°C) under intense gravitational forces equivalent to those found on the sun. The gas becomes a plasma and the nuclei combine to form a helium nucleus and a neutron, with a tiny fraction of the mass converted into fusion energy. Theoretically, a plasma with millions of these reactions every second can provide a huge amount of energy from very small amounts of fuel.
Although record-breaking sustained fusion energy was achieved earlier this year, many complex engineering challenges must be overcome before fusion energy can be produced as part of a large scale, affordable low carbon energy supply for the future. Key challenges include producing and managing the plasma where the fusion process happens, and developing materials that can tolerate extreme conditions, such as withstanding particles heated to hundreds of millions of degrees. Fortunately, there is a growing armoury of expertise.
Roles for nuclear energy
Achieving net zero carbon emissions by 2050 is an enormous challenge for all sectors. But decarbonising the industrial sector, which is responsible for 25% of emissions worldwide, is among the greatest challenges. Industry will require credible low carbon solutions to provide it with the continual supply of feedstocks and energy inputs it needs to keep processes running 24 hours a day, seven days a week.
Foundries, steelworks, paper mills, chemical plants, mineral products manufacturers and glass producers are all seeking new, cost-effective, low carbon feedstocks and energy sources, and there are few proven options from which to choose. Additionally, the net zero transition is predicted to give rise to a new wave of energy demand driven by the need to produce clean fuels such as hydrogen, ammonia and sustainable aviation fuel (SAF).
Wider uses of nuclear
The story for nuclear does not end at providing electricity to local or national grids. The pressing requirement for energy security, sustainability and resilience at a consistent and low cost demands that we look to deploy all the existing decarbonisation tools available to us, assessed on a level playing field. Nuclear is one option that delivers on all counts and is increasingly associated with the need to produce large quantities of low carbon hydrogen and heat to decarbonise a range of current and future industrial applications. These could include:
• Providing heat and electricity directly to paper mills to replace combined heat and power (CHP) plants.
• Delivering hydrogen to fire blast furnaces and glass factories.
• Providing heat for chemical processes, for example, ammonia and methanol production.
• Producing the hydrogen and CO2 feedstocks required to produce sustainable aviation and shipping fuels.
• Delivering low carbon heat and electricity to drive direct air capture (DAC) plants as part of a whole new industry to remove CO2 from the atmosphere.
Current decarbonisation plans for these sectors rely heavily on carbon offsetting or carbon capture, utilisation and storage (CCUS). Using nuclear to make these clean fuels could unlock the required additional production capacity, potentially at lower cost and with less risk. At a time when the optimal decarbonisation options remain unknown, relying on multiple production pathways significantly reduces the risk of failing to achieve net zero.
Industrial energy user needs The consistent, weather independent energy output from nuclear aligns well with current and future industrial energy demand. The provision of low carbon heat directly to industry at a range of temperatures is a unique proposition among low carbon solutions. Using nuclear for this purpose could:
• Reduce the requirement for back-up generation.
• Relieve the pressure on costly energy storage while increasing energy independence by reducing reliance on fossil fuel imports.
• Reduce potential risks associated with over reliance on CCUS and release valuable CO2 storage locations for other purposes, for example, storing environmental CO2 removed from the air or sea.
The technologies required to achieve these objectives are all available today but require investment and cross-sector support in order to emerge as commercial propositions.
Deployment and operating model
The nuclear sector is working tirelessly to develop these options and envisages a future in which nuclear power stations provide electricity, heat and hydrogen from one facility. The balance between these three outputs could f lex according to local and national energy requirements, and depending on the output and performance of other technologies.
In this way, a reactor operating at full capacity producing heat for industrial clusters could direct a portion of its thermal power output into electricity production when wind speeds are low, thereby supporting grid balancing. When wind speeds are high, a greater proportion of this heat could be switched to hydrogen production. All this would happen while consistently providing direct heat, as steam or hot gas, to local users via a series of heat exchangers.
Similarly, one or more reactors could provide an off-grid supply of electricity, hydrogen and heat to meet the specific needs of a large-scale user. user.