TPM Coordinates 'The Greening of Gas' Project
To mix hydrogen into the domestic gas network: that is the challenge
that those taking part in the EET-subsidized project, 'The Greening of
Gas' have set themselves. Project coordinator Dr Kas Hemmes (Associate
Professor with the Energy and Industry section) describes the many technical
and administrative difficulties of this promising idea.
Under the Kyoto Climate Treaty, the Netherlands is expected to reduce
its emission of greenhouse gases by six per cent (compared to 1990 levels).
The main greenhouse gases produced by the combustion of fossil fuels such
as oil, gas and coal are NOx (nitrogen oxides), SO2 (sulphur dioxide)
and CO2 (carbon dioxide). The idea of using hydrogen as a supplementary
energy source emerged in the 1970s. Hydrogen has a significant advantage
in that its combustion produces only water and no greenhouse gases. "Because
the environmental benefits are so obvious, some people do not understand
why the idea was not implemented a long time ago," states Kas Hemmes.
"Perhaps they think we can just dig a well and pump hydrogen out. Unfortunately,
it's not that simple. Pure hydrogen does not occur naturally. It has to
be derived from other energy sources such as natural gas, coal or biomass.
It can also be extracted from water by means of electrolysis."
Hemmes, who studied experimental and theoretical physics in Groningen,
gained his doctorate in 1986 with his research into magnetic recording.
However, he soon became interested in energy research. For fifteen years,
he conducted research into fuel cells with the Material Sciences and Engineering
department of Delft University of Technology. For the last eighteen months
he has been involved in the systems design for a national hydrogen distribution
infrastructure and the design of transition processes towards a hydrogen
economy. This work has been conducted within TPM as part of the 'Greening
of Gas' project, financed by the Ministry of Economic Affairs, the Ministry
of Education, Culture and Science and the Ministry of Housing, Spatial
Planning and the Environment (VROM) under the Economy, Ecolgy and Technology
The use of hydrogen as an energy source is not only hampered by its limited
availability. Another problem is that it is difficult to store or trans-port
in large quantities. "If we want to use hydrogen on a large scale, there
would have to be a network of pipelines covering the entire country,"
explains Hemmes. "Needless to say, this would entail a huge investment.
Our idea therefore becomes even more attractive: we are investigating
the possibility of using the existing gas infrastructure. By mixing hydrogen
into the natural gas, at least the transport problem is solved." Because
this 'new look at the hydro-gen economy' entails investigating a large
number of technical and administrative considerations, the project has
been split into two parts. The technical questions are being addressed
by the Delft Laboratory for Process Equipment, (API), the Faculty of Civil
Engineering and Geosciences, Electrabel, EcoCeramics, the Netherlands
Organization for Applied Scientific Research (TNO), Gasunie and the Universities
of Groningen and Eindhoven. These partners are concerned with such aspects
as fundamental combustion research, the effect of hydrogen/ biogas/natural
gas mixtures on pipeline materials, gas turbines and gas-fired engines,
research into new burner types, and the safety aspects of transporting
and distributing hydrogen-rich gas mixtures.
The other part of the project, coordinated by Dr Hemmes, involves TPM
working alongside Hoek Loos, the Faculty of Civil Engineering and Geosciences,
Schouten Research, Energy + i.d. and the City Of Rotterdam Port Authority
(GHR). It is primarily concerned with infrastructural development in the
technical, socio-economic and juridical contexts. Research is being conducted
into the costs-returns ratio, national and international legislation,
and the impact of the liberalization of the gas market. "From the technical
perspective, mixing hydrogen with natural gas in the existing network
could well prove the best solution, but this does not necessarily mean
that it will actually be implemented. There are many factors to be taken
into consideration. We live in an era in which economic interests are
paramount. Everything must be cost effective and market forces must be
allowed to prevail. We are looking at both the demand and supply side
of hydrogen/ natural gas mixtures. We are designing a suitable infrastructure
and conducting dynamic modelling for the transition process. In the final
phase, we hope to implement our ideas in the Rotterdam harbour district."
First and foremost, TPM's part of the project involves investigating existing
and potential hydrogen production techniques. These include the 'non-conventional'
techniques such as extracting hydrogen from biomass. If this is indeed
feasible, countless interesting scenarios emerge. "Suppose a group of
farmers have a pile of surplus biomass which is serving no other purpose.
They could use it to produce hydrogen which they will then add to the
gas network, wherever they happen to be. This may seem somewhat far-fetched,
but in the new liberalized gas market anyone will be allowed to produce
and supply gas, in theory at least. Of course, existing legislation must
Gas must comply with certain quality requirements and must have a certain
calorific value, as expressed by the Wobbe index. It is still uncertain
whether natural gas to which hydrogen or biogas has been added will meet
the quality requirements. If not, it may be appropriate to amend the legislation
allowing gas of a different quality to be supplied. At the moment, the
standard is the 'Slochteren norm', with all domestic gas-burning equipment
and most industrial equipment designed, built and regulated accordingly.
We simply do not know whether consumers and industrial users will be prepared
to convert to new burners and gas turbines, as they were required to do
in the 1960s when the Slochteren gas pocket first came 'on line'."
Consequences for the infrastructure
The addition of hydrogen to gas would not be without consequences for
the existing gas infrastructure. Hydrogen has a lower calorific value
than natural gas, which means that volumes must be increased.
Hydrogen-powered buses in Germany
|Kas Hemmes gives a brief
refresher course in chemistry: "Natural gas is actually methane, or CH4,
a com-pound of one part C and two of H2. One part of H2 has roughly one
third of the calorific value of CH4. This means that if you add ten per
cent hydrogen (by volume) to the natural gas, you have added only three
per cent energy value. In order to main-tain the same calorific value, you
have to transport a much higher volume of gas. It is not certain whether
the existing network of pipes would be able to cope."
Another interesting research question with regard to the infrastructure
is where the hydrogen should be physically introduced to the network. Gas
is always transported in only one direction along each pipe, whereby the
hydrogen can only be added 'upstream'. This is the major difference between
gas and electricity, which in theory can be returned from any point in the
The sub-project 'Demand-side Analysis of H2/NG Infrastructure' (NG stands
for Natural Gas) is studying the possible applications for the hydrogen/gas
mixture. Could consumers use it to fuel a central heating boiler? Would
industry be better off, or would the disadvantages outweigh the benefits?
"Of course, we want to ensure that there are only advantages," states Hemmes,
"since this would represent a significant motive for getting the process
off the ground. For industry, it is extremely important that the use of
hydrogen serves to reduce CO2 emissions, as this will enable future economic
gains to be made. The Vogtländer Commission, appointed by the Ministry of
VROM, favours a system of trading in 'emission rights'. This could prove
a valuable and efficient instrument in tack-ling the emission of greenhouse
gases. Companies which produce relatively little CO2 could make extra profit
by selling their emission rights, their 'quota' as it were. This system
is particularly interesting for the metals industry and companies such as
Corus, which use cokes to convert metal oxides into the finished product,
thus producing enormous quantities of CO2."
"In the long term, it seems economically viable for industry to convert,
at least partially, to the use of hydrogen/ natural gas mixtures. Unfortunately,
this is not the case in the short term. We run up against a paradox. A familiar
industrial process whereby hydrogen can be produced from natural gas itself
is steam methane reforming. The petrochemicals industry uses this process
on a large scale to remove sulphur compounds from crude oil. However, it
always entails conversion losses: twenty per cent of the energy is simply
lost. In the first instance therefore, if industry wishes to convert to
the use of hydrogen, greater quantities of natural gas will be required,
which will cost more."
It is therefore extremely important that additional benefits are created
for hydrogen mixtures, apart from the reduction in diffuse CO2 emissions.
The transition process must include incentives to encourage consumers and
industry to adopt the new fuel form. Transition -management and dynamic
modelling of transition processes fall within the TPM sphere of expertise.
What technical and administrative instruments can serve to promote a government
objective such as emissions reduction, and how can one monitor the results?
Kas Hemmes suggests one possibility: "If hydrogen is introduced to the main
gas net-work, every household and every company in the Netherlands will
be able to use it. One of the concepts we are investigating is that of micro-generation.
Every building would have a fuel cell powered by hydrogen and producing
electricity. Some energy is converted into heat during this process and
would normally be lost. In our system, it can be used for heating. The gas
is therefore used to the full. Because H2 will already be in the gas, no
reformer (a sort of miniature chemical conversion plant) will be required.
The fuel cell will filter the hydrogen out, as it were."
Another possible application for the mixture is as an automotive fuel. A
80/20 mixture of hydrogen and natural gas (which is already on the market
under the trade name 'Hythane') has extremely good combustion properties.
It has lower NOx emissions, whereby great environmental gains can be made
when used in cars with an internal combustion engine. Moreover, provided
good separation techniques become available, the hydrogen can be extracted
from the mixture for use in electric cars equipped with fuel cells. Research
is also being conducted into possible industrial uses for the CO2 which
is a by-product of hydrogen production. This could be used in oil and methane
Hemmes concedes one fundamental problem in all this. "Although the addition
of hydrogen to the gas net-work does seem to have some major advantages,
there is a danger that this approach will lead to 'path dependency'. It
would stand in the way of a transition to a 100% hydrogen economy, since
once the proportion of hydrogen in the mix has been established, it will
not be possible to increase this time after time. Doing so would require
further modifications to industrial gas turbines, which is an extremely
There is a very high likelihood that if this option is adopted, the percentage
of hydrogen in the mix will be pegged at 5 or 10% for ever more. A one-step
transition may therefore be preferable. We in the department of TPM are
working alongside our partners to identify the pros and cons of all the
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