What are the energy sources of the next generation?

 

 

 By: 

Bruno De Wachter

/ Published on: 

Thu, 01/07/2010

Last September, an interesting new analysis was published by two California-based think tanks: Searching for a miracle / "Net Energy" limits & the fate of industrial society. The report, written by Richard Heinberg, is a joint initiative by the International Forum on Globalization and the Post Carbon Institute.
As with the book Sustainable energy / Without the hot air by David Mc Kay (on which we reported earlier on this blog), the report by Heinberg has as its principal merit a comprehensive analysis of the energy problem. With global warming becoming an increasingly important topic and the all-time peak of global oil production most probably behind us (July 2008, 87.9 million barrels per day), we can no longer hide behind local solutions. The world’s energy use will need a radical change in the upcoming decades.
But contrary to David Mc Kay’s book, Heinberg’s study also takes the cost, the reliability, and the potential transition speed of possible energy resources into account, as well as their physical and technical potential. However, Heinberg looks at the energy solutions separately and does not propose scenarios in which demand and production figures are added up and matched, as Mc Kay did.
It is worth noting that both experts put emphasis on the need for energy conservation and on the advantages of electricity as an energy carrier. Another common viewpoint of both experts is that they see only a very limited potential for biomass, ethanol, and biodiesel. Both also view wind energy and Concentrated Solar Power (CSP) as very powerful options for the future.

Assessing the available energy technologies

The report by Heinberg analyses 18 different energy sources. It is notable that all of them are presently available on the market in a more or less developed form. Heinberg clearly does not pin much hope on new 'magical' solutions that still only exist as concepts or laboratory models. Taking the urgency of the matter into account, he postulates that we will have to make do with the solutions we already have at hand. It will take less time to solve the primary issues of existing technologies than it will to develop entirely new energy solutions from scratch, and we must always bear in mind the risk that the theoretical or hypothetical new energy solutions may never deliver at all.
The report uses nine criteria to assess the potential future of the 18 available energy sources. Those criteria can be grouped into six basic categories:

• Direct monetary cost
• Environmental impact
• Renewability
• Potential scale of contribution
• Reliability
• Energy Return On Energy Investment (EROEI).

The importance of 'net energy'

Much emphasis is laid on the EROEI criterion, also called 'net energy'. It is seen as a key figure to understand the world energy system. The EROEI of US oil was 100:1 in 1930. It fell to 30:1 in 1970, and is currently less than 20:1. According to Heinberg, the high EROEI that oil formerly enjoyed was directly responsible for the development of the energy guzzling economy we have today. The drama of his argument lies in his assertion that it is very unlikely that we will find a new energy resource with such a high EROEI any time soon.
Even though the reserves of oil and natural gas are still significant, the EROEIs of those resources will most probably continue their steep decrease. This is also the case for coal but to a lesser degree, since today coal still has an EROEI of around 65:1. Heinberg shatters the illusion that we still have coal available for a few hundreds of years. He predicts the world coal peak around 2025 and a steep decline in its EROEI after 2040. The minimum EROEI necessary to sustain a modern industrial society is considered to be 10:1. Carbon Capture and Storage (CCS) will make the EROEI of coal decline even faster, and for this reason Heinberg does not see coal with CCS as a sustainable solution.
The report’s general conclusion is that, even without taking climate change and other environmental issues into account, we will be forced to shift towards a non-fossil-fuel economy in the coming decades.

Which technologies have the most significant potential?

What are the cards we have in hand to build a new energy economy? As could be expected, Heinberg does not foresee any silver bullet. For various reasons, he downplays the possibilities of nuclear energy, hydroelectric energy, passive solar energy, biomass, biodiesel, and ethanol. Nuclear energy has many drawbacks: uranium is non-renewable, the initial investments are huge, the environmental impact of the fuel cycle is high, and nuclear power plants require a great deal of water. Hydroelectric energy is either on too small a scale and thus does not add up, or too large a scale with local environmental and social impacts that are in most cases too high to be acceptable. Passive solar energy is certainly a valuable concept, but too limited in scale to contribute significantly to the world’s energy needs. Biomass, biodiesel, and ethanol have an EROEI below 5:1.
The report sees significant potential for wind energy, solar photovoltaic energy (PV), Concentrated Solar Power (CSP), wave energy, and tidal energy, but even the potential of this 'energy mix of the future' is limited. PV has serious drawbacks in its relatively high cost and relatively low EROEI, and the potential of tidal energy is limited to a few regions of the world. Wave energy will need more research before we know its true potential. So, most probably, wind energy and CSP will have to make up the largest share in any viable future energy mix.

Electricity as the preferred energy carrier

Apart from the energy source question, there is also the question of which energy carrier is going to take over the role that is currently performed by liquid fossil fuels. Hydrogen presents problems that are so substantial we are unlikely to ever see a 'hydrogen economy', says the report. Its energy density per unit of volume is too low and too much energy is lost in the various conversion steps a hydrogen economy entails. Electricity has more potential, but if it is chosen as a systematic energy carrier, a few barriers still have to be overcome. The energy density of electrical batteries needs to be enhanced, and solutions need to be developed to efficiently transport electricity from remote renewable production centres to distant population centres.

Energy conservation absolutely essential

Given the limited potential of the 'energy mix of the future' as stated in the report, the central message of Searching for a Miracle is a pessimistic one. This is in contrast with the relatively optimistic point of view of David Mc Kay in Sustainable Energy / Without the hot air. According to Heinberg, it will be impossible to ever bring the entire world population up to the current American energy standards. Even bringing the world population up to European standards seems too ambitious. Maintaining today’s world average energy use per capita is most probably the only thing we can hope to accomplish, and even that will require sacrifices in terms of cost, quality, and reliability of the energy.
Heinberg sees energy conservation, mitigating population growth, and limiting economic growth as indispensible if we are to develop a sustainable energy economy. In the chapter 'The case for conservation', he lists several possible measures. Those include, among other things, the construction of highly efficient rail-based transit systems, the retrofit of building stocks for maximum energy efficiency, the internalisation of the full costs of energy to reflect its true price, aggressive measures for demand-side management, and intensive water conservation programmes. That last argument is based on the fact that currently high amounts of energy are used by pumps for moving water.

A 100 GJ per person per year should suffice

Heinberg concludes his report on a positive note. We should not strive to bring the world up to current American energy standards. He cites Vaclav Smil, who investigated the relationship between the annual energy use per capita and the feeling of well-being. According to those statistics, the feeling of well-being expands proportionally with the per capita energy consumption up to about 100 GJ per capita per year. Above this figure, the feeling of well-being does not continue to follow the increasing energy consumption and even starts to go down again.
Consequently, Heinberg takes 100 GJ per capita per year as a general target and not the 325 GJ per capita per year as currently consumed in the US. Note that David Mc Kay used a similar guiding number, when he proposed to bring the current rate of 178 GJ/capita/year (125 kWh/capita/day) in the UK down to 105 GJ/capita/year (80 kWh/capita/day) through energy efficiency. The world average in 2008 was 74 GJ/capita/year.

Comments

Consumption figures

By Jean-Bernard MICHEL / Published on Wed, 01/19/2011 

Actually the world average primary energy consumption is not 74 but 70.8 GJ/capita/year, based on the Economic Research Service of the US department of agriculture data base from 1969 to 2008 (USDA, 2010). Accoding to the Swiss Federal Institute of Technology a sustanable figure should be 63 GJ/capita/year and not 100 !
Basis for calculation:
World consumption in 2008: 11294.87 Mtoe
World population in 2008: 6682477937
1 toe = 11630 kWh
Anyway, the change will become inevitable and will coincide with a change of paradigm in the way we look at progress, security, and well-being

(Source :Leonardo )