the power of osmosis

I don't pretend to understand how this works, but it sounds like an interesting prospect for renewable energy.

When placing a semi-permeable membrane (i.e. a membrane that retains the salt ions, but allows water through) between reservoirs containing fresh water and sea water respectively, a net flow of water towards the salt water side will be observed. If the salt water compartment has a fixed volume the pressure will increase...

The energy from the available pressurised water can be used to generate environmentally friendly renewable energy. This is if the mixing can be carried out by controlling the pressure on the salt water side. The process is called pressure-retarded osmosis (PRO) and in a technically feasible process approximately half the theoretical energy can be transformed to electrical power, making osmotic power a significant new source of renewable energy.

The pressure-retarded osmosis power plant is similar to a reverse osmosis desalination plant running backwards. However, the PRO plant generates power from fresh water instead of consuming power.

Apparently, the trick lies in developing an efficient membrane. Statkraft AS, the company developing the process, are hoping for a production level of 5W/m2 of membrane, at which point they believe the process will be financially competitive. They are planning a 10kW prototype plant to test the process outside the lab. The power plants can be built underground, and are ideal for cities where freshwater rivers join the sea.

A 25MW plant would only require some 40,000m2 of land even if it is located above the ground. Compared to a wind farm or the area required to harvest biomass to produce the same amount of energy, the osmotic power plant is very compact.

The investment cost for an osmotic power plant is relatively high per installed power compared with other renewable energy sources as, for example, wind or solar power. The main difference is that osmotic power plants will be designed for base load operation and are thus qualitatively different from most other new Renewable energy sources.

[Source: The Institution of Engineering and Technology]

trees are overrated

They're messy, interfere with the view, and can be really tricky to uninstall without leaving a trail of destruction. But don't take my word for it - here's the full review of trees. (Don't miss the readers' contributions.) [via kottke.org]

energy efficiency is the quickest strategy

Developing countries like South Africa often don't have the luxury of being able to invest in energy efficient equipment, particularly when the cost of electricity is as low as it is. Even competitive countries like Germany have been reluctant to improve efficiencies, for fear that the capital cost would price their industries out of their markets, despite reduced energy inputs, and South Africa is also vulnerable. But the current power shortage in sub-Saharan Africa, together with the prospect of imminent price hikes (as in Germany), is rapidly focusing attention on ways to reduce energy consumption without slashing economic growth.

Improved efficiency is probably the easiest - and certainly the quickest - way to address South Africa's energy crunch, and hopefully Eskom and industry will quickly come up with a plan for shared responsibility to work themselves out of the daily blackouts that are plaguing the country. There are lots of alternative ways Eskom could spend the billions it has earmarked for nuclear energy.

In an op-ed in yesterday's Cape Times, Terry Bell pointed out that there are a number of potential mega-projects across Africa that are either planned for implementation or waiting for the right moment to be revived, and while all mega-projects carry risk, these would surely be a safer investment than the untested PBMR nuclear reactor that is still on the cards. From the Kwanza River power station in Angola, to the Grand Inga on the Congo River (estimated to be able to produce up to 40 000MW, or almost equal to South Africa's total current generating capacity), these projects are not new, and neither is the idea of an SADC (Southern African Development Community) power grid linked to a pan-African grid. They are tested, they are feasible, and they could strengthen Africa as a power bloc.

On a much smaller scale, South Africa could also learn from Britain, which has set a target to build only zero-carbon homes from 2016. South African homes are not heated, so the potential savings are not as great as the potential £300 savings available in Britain from reduced household energy demand, but South African authorities could be developing green building codes for all types of buildings to improve the overall sustainability performance of the built environment, including measures to reduce the amount of energy embodied in the construction materials. South Africa could also learn from Britain's failure to set up the necessary support mechanisms to encourage householders to invest in energy saving measures. Again, leapfrogging past the mistakes of others.

the road to fame

Pop rock meets tarmac. Well, not exactly the music, but the CDs. Industrial-strength recycling for an industrial juggernaut.

when is green not green?

There are tools for measuring your personal carbon footprint, tools for determining the embodied energy in construction materials, tools for designing low-carbon buildings, and tools for getting developments accredited for various measures of sustainability. The choice is growing every month, and therein lies a challenge: how to standardise what we mean by "sustainable". As international agreements evolve through processes such as the current negotiations around the next phase of the Kyoto Protocol, we will be forced to converge on an agreed standard - at least as it pertains to carbon emissions. (Though George Bush seems set on developing his own carbon market in parallel, reminding me of the old Betamax vs. VHS battle for ascendancy in video technology, or the current Blu-ray vs HD DVD war.) In the meantime, we will be faced with a growing number of disputes over developments like this one in Maine, USA.

green architecture is not about solar panels

Architect Frank Harmon, interviewed in the previous issue of Dwell (Dec/Jan 2008), suggests that good architecture respects climate and region, and this is why vernacular architecture is inherently sustainable: it makes use of what is available locally - materials, labour and building methods that suit local conditions - and produces buildings that are comfortable without the need for climate-fighting technologies.

A colleague of mine recently suggested that the sustainability performance of a building is 80% design. The rest is some combination of technological interventions and changes in building management and operational procedures. For example, if you want to reduce the amount of waste coming out of a building and ending up on a landfill site, you might set up an on-site recycling operation to create new products; or you might reduce the load on municipal sewage treatment works by using biogas digesters to turn some of it into a useful energy stream. More likely, you will take the less ambitious approach of looking at what products and resources are brought into the building, and how packaging and other waste is handled and disposed of, and set up waste sorting systems to send it off to recycling plants. Yet, in many countries, even basic recycling is rare; and while incentives and penalties would help focus minds, part of the issue is still design. Buildings should be arranged and fitted out to make waste management an obvious part of doing business.

In dealing with waste, energy, water and other aspects of building operations, there are some things that might take place without people in the building even knowing it (like grey water recycling or using solar-generated electricity), but we can't expect that technology will sufficiently reduce environmental impacts without some change in behaviour, so there must be awareness. This is why some buildings are designed deliberately to have occupants open and close ventilation openings and adjust sun shades throughout the day, when it is perfectly possible to have this done by electric devices run on timers and temperature sensors. The combination of active and passive systems is a design choice that, again, depends on regional and site conditions, and what the building will be used for.

Sustainability performance is about a lot more than resource management, and one of the less tangible aspects is social wellbeing. On its own, this is a worthy design consideration, but there are obvious financial and economic impacts related to how people experience buildings. Or, judging by the ongoing development of big box stores across North America, perhaps it's not so obvious.

During my brief and uncomfortable stint doing traffic impact studies for big box stores while I was based in Toronto, I was amazed at the complete lack of sensitivity of companies like Wal-Mart towards local conditions. If the box and its parking didn't fit on a potential site for a new store, they would rather abandon the site than change the building. They had a formula, and it worked. It was efficient - or so it appeared to them - and they saw no need to change. Over time, the formula does indeed change, as evidenced by current explorations into ways to make big boxes somehow greener; but once a path is set, the designers and other professionals tasked with rolling out acre after acre of steel and tarmac are instructed to stick with the plan.

With this mindset, sticking solar panels on the roof and installing grey water recycling and low-flow toilets might win green points, but it will do little to improve sustainability performance in its broader sense. I confess that I was a regular Toronto customer of Home Depot - another big box retailer - because of the convenience, huge selection of products, and reasonable prices. I am sure that's why people will continue to flock to shop at these places as long as they are able. But I also suspect that the likes of Wal-Mart and Home Depot have never seriously considered whether they could attract more customers through a building design strategy that is genuinely responsive to sustainability principles.

Will more people come if there is natural lighting, fresh air, variety of local building materials, aesthetically pleasing building designs, and a view of the adjacent forest? MPreis, a chain of design-conscious Austrian supermarkets, thinks the answer is 'yes', and have built dozens of supermarkets that respond to the local context. According to an article in the same issue of Dwell as the interview with Frank Harmon, "each MPreis market is architecturally unique and linked to the others not through the same front entrance or predictable location of the deli, but by an effort to make MPreis and modern design synonymous." Put one of these next to a standard Canadian Loblaws supermarket, and you are bound to get shoppers preferring to hang out at MPreis. As the move towards organic food products has demonstrated, it's not all about price and efficiency and the perfectly shaped apple.

One last thought. To make buildings that respond to the natural landscape, there actually needs to be a natural landscape, and for the vast majority of North American developments now being built (whether big box stores or residential neighbourhoods), that is not the case. Developers invariably clear-cut and level the site before plonking down the box or house or apartment block. A design-conscious approach will have to change more than the building design process. It will have to change the whole approach to site selection and preparation. This will cost more, but if MPreis is right, people do respond to high quality environments, making them financially worthwhile. And we will all benefit from kinder cities.

And finally, an example from architect Eduardo Cadaval in Mexico, making design decisions based on what's available locally.

[Update on 30 January 2008: Here's a report on green building design analysis software.]

carbon footyprint

By the time the 2010 FIFA World Cup rolls around to South Africa, climate change negotiations should have concluded with commitments by both developed and developing countries to reduce greenhouse gas emissions, and South Africa will have to start making a serious effort.

By then, organisations like FIFA will also be facing increasing pressure to reduce the environmental impacts of their events; so it is interesting to see what E.ON (a green energy generator in the UK) is doing in its carbon footyprint campaign, through which it is hoped that the 45,000 tonnes of carbon dioxide produced by the FA Cup will be offset, making the competition carbon neutral. The campaign will provide incentives for fans to make pledges to reduce their carbon output in the way they run their homes and how they watch or travel to matches.

trains and planes on the carbon battlefront

It's interesting to watch the railway and airline lobbies wage battle for the hearts of environmentally-conscious long-distance travellers. Trains and planes are competing with each other in a growing number of markets, but on the alternative fuels front, airlines are at a distinct disadvantage.

Given security of supply, railways could switch to biodiesel immediately, and trials have begun using blended fuels. (Interestingly, the first biodiesel-fueled trains were run in 2002 by Indian Railways.) Despite the marketing hype, it's not so clear that this would cut carbon emissions; but it would at least reduce dependence on fossil fuels, and the Indian approach of making biodiesel from plants such as jatropha, mahua and karanji would create jobs while avoiding some of the pitfalls of biofuels.

Then there's the approach of using electrified trains - in cities, at least - which removes the need for liquid fuel altogether, making it possible to use a mix of any energy sources that can be fed into the grid: wind, sun, sea... The solar panel on your roof could be doing its bit to get you to work in the morning.

Meanwhile, the airlines aren't giving up the fight. If they have fewer alternative fuels immediately available, they figure they can at least earn points by participating in climate change research to see what their impacts are, and what can be done. They've also got the fallback position of encouraging passengers to purchase carbon offsets, but have a long way to go, as a miniscule proportion of air travellers currently purchase offsets, and many of these are virtually worthless tree-planting exercises.

Sir Richard Branson is sitting pretty with a foot in both camps. In true Branson style, there's the $25 million Virgin Earth Challenge to see who can come up with the killer carbon reduction app. But as he has pointed out, the answer is not only about fuels and technologies. It's also about standards and operating procedures. Sometimes we just have to change the way we do things to reduce carbon outputs, and Sir Richard maintains that airline procedures could be tweaked to achieve just that. He has proposed towing aircraft to the runway, and the International Air Transport Association (IATA), which represents 250 airlines, says that "an overhaul of air traffic control operations could result in a 12 per cent reduction [in emissions] if it meant planes didn't have to circle while waiting for a landing slot."

They can fiddle - for now - but it is likely that the current round of climate change negotiations at the UNFCCC will bring international travel under the carbon emissions umbrella from which it is currently exempt. And as Climate Ark notes:

No government - or airline - will admit it, but limiting the number of flights individuals and airlines are allowed could be the long-term solution. Some economists argue that we are already going down the road towards carbon rationing. The only difference between carbon trading and carbon rationing is that in the former system, those who exceed their allocation, or ration, can buy in extra credits. In the future, this option may become prohibitively expensive, or illegal.

[Update on 27 January 2008: An article in the Guardian today points out some of the current thinking about improved airplane construction methods to reduce weight, new types of engines, and operational procedures that would reduce carbon impacts of air travel. Some believe that planes could halve their fuel consumption by 2020.]

facts on china

We all know that China has recently become the world's biggest producer of carbon dioxide, but here are a few things you might not know:

1. There are hotel rooms in Beijing that switch off all lights and appliances when you aren't there.
2. Shanghai's maglev train is the fastest in the world.
3. Beijing has street cleaners who ride on bicycles.
4. Cars in Shanghai cost more to licence than to buy.
5. 60 percent of the world's installed solar capacity is in China.
6. Beijing's National Indoor Stadium, to be used for the 2008 Summer Olympics, has 1100 solar panels.
7. In 2005, China ranked 10th in the world with 1,266 megawatt in-grid wind power installed capacity.
8. By the end of 2004 China had produced 200,000 off-grid wind turbine generators, and was ranked number one in the world.

Here are a few more thoughts on China's environment challenge.

crowdsourcing energy

Crowdsourcing usually refers to the deployment of many people to generate or develop ideas or data. Here's another application of the term: gathering useful energy from crowds.

This is yet another example of capturing energy that is otherwise going to waste. Commuters heat up the Central Station in Stockholm - transfer the heat to water, and pipe it to office buildings. Voila.

And I read somewhere about an idea being developed to harness the energy of people walking on steps in a stadium, but can't find it now...