Options for low-carbon space and water heating include: • Low-carbon Hydrogen replacing natural gas in the gas network.• Individual Electric Heat Pumps using renewable electricity. • District Heating (DH) with large Combined Heat and Power (CHP) plants and renewable heat. Low-carbon Hydrogen and Electricity even for Heat Pumps are still poor exergy matches for space and water heating.Modern District Heating networks have an annual average water flow temperature of about 70o C.So by the Second Law of Thermodynamics, they give the best possible exergy match to space and water heat loads. Compared with current gas boilers, large CHP plants give large savings in fuel consumption and CO2 emissions for heat. They can be Combined Cycle, fuelled with gas or biomethane, or Steam Cycle, fuelled with Municipal Waste or Biomass.Only District Heating can harness low-carbon renewable heat sources, such as solar and deep geothermal heat, as well as excess renewable electricity. Unlike gas boilers and electric heat pumps, District Heating enables the central CHP and renewable heat plant to be halved in size, due to the Diversity of the individual heat loads. Copenhagen, using District Heating with heat from large Combined Heat and Power plants and renewable sources, is on track to be zero-carbon by 2025.
Planning the appropriate renewable energy installation rate should balance two partially contradictory objectives: substituting fossil fuels fast enough to stave-off the worst consequences of climate change while maintaining a sufficient net energy flow to support the world's economy.
Famine, economic collapse, a sun that cooks us: What climate change could wreak — sooner than you think.It is, I promise, worse than you think. If your anxiety about global warming is dominated by fears of sea-level rise, you are barely scratching the surface of what terrors are possible, even within the lifetime of a teenager today. And yet the swelling seas — and the cities they will drown — have so dominated the picture of global warming, and so overwhelmed our capacity for climate panic, that they have occluded our perception of other threats, many much closer at hand. Rising oceans are bad, in fact very bad; but fleeing the coastline will not be enough.Indeed, absent a significant adjustment to how billions of humans conduct their lives, parts of the Earth will likely become close to uninhabitable, and other parts horrifically inhospitable, as soon as the end of this century.
Topic 1) emphasises the urgency of energy transition.Topic 2) is the main focus of the document, with the paper by Sgouridis et al, 2016.This identifies the relationship between the remaining fossil fuel emissions cap, the transition time, and the required investment in Renewable Energy (RE) supply plant.Topics 3) and 4) refer to the initial conditions prior to the energy transition.Topic 5) compares the Energy Return on Investments (EROIs) of Renewable Energy (solar and wind power) supply measures with the weighted average value of 20 assumed by Sgouridis et al.Topic 6 is concerned with the global limits of renewable power sources.Where Topics 3) and 4) deal in UK quantities, Topic 6) deals in Global quantities. However, the UK must expect to use only a proportionate share - e.g. equal per capita.Topics 7) and 8) consider energy demand measures as complements of the supply measures assumed by Sgouridis et al. They refer to two papers by Cullen and Allwood et al, 2010 and 2010.Including energy demand measures will greatly ease an energy transition within the constraints, such as 2 C global warming.
'Planning the appropriate renewable energy (RE) installation rate should balance two partially contradictory objectives: substituting fossil fuels fast enough to stave-off the worst consequences of climate change while maintaining a sufficient net energy flow to support the world’s economy. The upfront energy invested in constructing a RE infrastructure subtracts from the net energy available for societal energy needs, a fact typically neglected in energy projections. Modeling feasible energy transition pathways to provide different net energy levels we find that they are critically dependent on the fossil fuel emissions cap and phase-out profile and on the characteristic energy return on energy invested of the RE technologies. The easiest pathway requires installation of RE plants to accelerate from 0.12 TW p yr –1 in 2013 to peak between 7.3 and 11.6 TW p yr –1 in the late 2030s, for an early or a late fossil-fuel phase-out respectively, in order for emissions to stay within the recommended CO 2 budget’.
So the early fossil-fuel phase-out requires the installation of RE plants to accelerate by 7.3/0.12 = 61-fold and the late phase-out by 11.6/0.12 = 97-fold. Further delay would mean that there is no solution.
Christiana Figueres and colleagues set out a six-point plan for turning the tide of the world’s carbon dioxide by 2020.
In the past three years, global emissions of carbon dioxide from the burning of fossil fuels have levelled after rising for decades. This is a sign that policies and investments in climate mitigation are starting to pay off. The United States, China and other nations are replacing coal with natural gas and boosting renewable energy sources. There is almost unanimous international agreement that the risks of abandoning the planet to climate change are too great to ignore.