Hydrogen future

Doomsday may be at hand for petrol-heads but not for fossil fuels. HUGH DE LACY peers over the hydrogen horizon.

The car you may be driving in 40 years’ time is likely to be missing a drive train, gearbox, differential or even an internal combustion engine.

Instead, it will be likely powered by electricity sourced a fuel cell burning pure hydrogen (H) and emitting nothing but environmentally-friendly oxygen and water. Probably by that time too (around 2050) new buildings could house their own hydrogen fuel-cell stationary electricity generating plants, reducing dependence on a national grid operated by large generating companies and where there were once petrol stations, there may be hydrogen stations.

And where there were once oil refineries, there may be plants making hydrogen out of fossil fuels and sequestering the carbon dioxide by-product deep underground.

Other plants, driven by wind, hydro, tidal and solar-powered renewable electricity generators, may be making hydrogen by electrolysing water.

Such is the hydrogen economy that is widely predicted within a few decades to succeed oil globally as both the major stationary generator of electricity, and as the overwhelmingly dominant transport fuel. And, if it comes about, New Zealand will be independent of imported fuels. The 11 billion tonnes of recoverable low-quality brown lignite coal in Otago-Southland would play a pivotal role in this country’s conversion to the hydrogen economy. The Government is already investing in the pilot plant and technology that will keep the country abreast of the changes towards a H future.

CRL Energy, half-owned by the National Institute of Water and Atmospheric Research (NIWA) and the NZ Coal Association, has a $6 million pilot plant at its Gracefield campus at Lower Hutt that’s been converting coal into hydrogen since 2004.

The hydrogen is burned in a 5kW alkaline fuel-cell that converts it to electricity, and last year the government stumped up a further $530,000 for CRL to plot a pathway for the country towards the hydrogen economy.

The scientist leading the project, Tony Clemens, says this pathway is predicated on New Zealand becoming a full-blown hydrogen economy by 2050, at which time it would need 1.2 million tonnes of the gas, generating about 150 petajoules (pJ) of energy.

“There will be additional amounts needed for stationary applications, but it is generally felt that the big demand for hydrogen will occur when fuel-cell vehicles become economically viable. At the current rate of natural gas discovery – around 60pJ a year – this [natural gas] option will not be sufficient,” says Clemens.

“Even the discovery of another Maui-sized field will bring only about 25 years of supply, whereas the known lignite reserves are sufficient for over 400 years’ hydrogen production at the estimated 2050 demand.”

If hydrogen were to be generated by electrolysis using electricity from renewables, an estimated 280 to 350pJ of energy would be needed, he predicts.

“Ministry of Economic Development (MED) predictions for future economically viable untapped electricity generation indicate less than half this amount may be available from these sources, though this depends on how much the energy sector is prepared to pay for renewable electricity.”

Lignite’s role will be to fill the gap between what renewables can provide and what the country needs, but there’s no need to wait until the hydrogen economy is a reality before launching into the gasification of coal.

“Coal gasification, the chief enabling technology for hydrogen production from lignite, generates an initial syn-gas product that may, using existing technologies, be used to make a variety of other products which already have a market value in the energy sector – electricity, liquid hydrocarbons, synthetic natural gas – as well as chemicals such as urea.

“So the lignites could be used to generate one, or a combination, of these here-and-now products, and when the demand for hydrogen begins to grow, the production process could be altered to meet that demand,” Clemens says.

This short-term potential of lignite has already been recognised by both listed New Zealand company Lime and Marble (L&M) and state-owned collier Solid Energy (SE), which are carrying out a feasibility studies into gasification plants to be built somewhere in Otago or Southland. L&M’s could be up and running as early as 2012.

SE is also well down the path to developing a system of underground sequestration of such plants’ carbon dioxide by-product.

According to the Ministry of Economic Development, there are a dozen huge deposits of lignite scattered through the two southernmost provinces, any one of which could provide New Zealand with 71 million tonnes of transport fuels (15-20 years’ supply), 127 years’ supply of fertiliser plus exports worth $540 million a year, the South Island’s entire electricity needs for 60 years, and all the nation’s methanol requirements plus exports worth a further $1 billion a year.

The Otago-Southland lignite fields are a substantial resource even by world standards, representing 100,000petaJoules of energy, and comprising low-ash, low-sulphur deposits in easily accessible seams at least 10 metres thick.

The gasification plant L&M is considering would use five million tonnes of lignite a year – 12,000-14,000 tonnes/day – to produce 50,000 barrels of liquid fuel per day, enough to make New Zealand self-sufficient in diesel fuel.

So one way or another, the country’s future in the hydrogen economy seems assured.

Between then and now though, there are technological and cost barriers to be overcome, according to John Rampton, an MED energy policy analyst.

New Zealand will be led into the hydrogen economy by the likes of China, the United States and the European Union, he says.

“They’re the real drivers behind it, and they’ve all got their different rationales.”

For the US the environmental issues are the most pressing, backed up by a desire to reduce America’s dependence on imported oil.

Environmental concerns, especially transport emissions, also dominate the EU view, while China is increasingly worried by localised urban air pollution.

Rampton reckons it’s too early to say wherever New Zealand’s huge lignite deposits will necessarily pave this country’s way into the hydrogen economy.

“There are all sorts of technologies that may come to the fore,” he says, and the uptake of any of these could be affected by externalities such as charges on greenhouse gas emissions.

“There is so much water that has to go under the bridge in research and development with respect to hydrogen, and to some of the mitigation factors such as carbon capture and sequestration.

“That’s not to say that coal may not be viable – it’s just far too early to make such assumptions.”

That said, he concedes that New Zealand is well positioned to produce hydrogen from coal if that turns out to be the way the rest of the world goes.

The process

Gasification is the process for extracting hydrogen from fossil fuels, the by-product of which, carbon dioxide, will be sequestered in deep underground structures like coal seams, making it carbon-neutral.

Electrolysis, powered by electricity, is the means of extracting hydrogen from water, with the electricity being generated by either renewable – solar, wind, tidal, hydro – or conventional fossil fuel combustion.

One particular synergy between renewable electricity generation and the hydrogen economy is with wind power which is no respecter of peak demand cycles.

Wind could supply the national grid by day, then switch to powering electrolysis plants extracting hydrogen from water by night.